Categories
Making Projects

Blogma Week 6

Blogma

 
Intro to Physical Computing
Fall, 2003
Jeff Feddersen

Week 6


The site that Morgan found is really cool.


And here is another: scitoys.com.
Any site that has a link named “Fun with High Voltage” has to be good.


Take a 9-volt battery and touch it to a piece of steel wool. Instant fun!


I bought the radio kit from Radio Shack. It was kind of fun to put together. It would make a good homework assignment for people still getting used to electronics.
The kit uses tightly coiled springs to hold wire leads in place, rather than solder. I think I might use those in my projects.




Front/Top



Back/Bottom

For the Halloween class, Ana and I will try to make a disembodied hand (when else do you ever see the word ‘disembodied’ except when refering to a hand?).
There are many possible ways to do this, but I think we’ll go with a single motor and some string inside a glove. Maybe some broken chopsticks for bones.


I was working with Christina Goodness (she’s in Milmoe’s section) on programming the bx24 to light up one of those 7-segment LED displays.
Neither of us could get the print function to work! Everything else seemed fine, but it was hard since we could never see the pin values.
We both use v2.1 of the software at home, but were using v2.0 at school.
I wonder if by initially using v2.1, the chips somehow got ‘calibrated’ to that version of the software, and thus wouldn’t work with v2.0.


I built a simple brushless motor, using magnets, copper wire, and the most essential part, one of those magnetic switches Jeff Described.





The wire is wrapped around a large iron bolt, making an electromagnet. A tube is perpendicular to the bolt, and the tube has 4 regular magnets, with the south pole facing out.
At rest, one of the four permanent magnets is near the switch, keeping it closed because of the magnetic field.
When current is on, the electromagnet generates a magnetic field that pushes away the closest permanent magnet, which rotates the tube about 45°.
This causes the magnet on the far side of the tube to move away from the switch, which then turns off because the field is removed.
The switch being off opens the circuit and the electromagnet loses its field.
The tube then rotates another 45° because at this point another permanent magnet is near the iron bolt, which is no longer magnetized, and attracts the magnet.


So, the switch turns on and off 4 times for every revolution of the tube, clicking audibly


The design and parts came from a Web site which I can’t remember now.
The tricky part was positioning the bolt, magnets, and switch in such a way so that the tube spins with just enough momentum to bring it through an entire 1/4-turn.
Sometimes I have to start the thing spinning manually, because the electromagnet isn’t quite strong enough to push away the first magnet when at a dead stop.


I had to eat a few boxes of Fruity Pebbles in order to get the UPC symbols, mail them in, and get my free “Wild Planet Spy Detector”.





It looks kind of like a spaceship. Maybe I can make a cool thing with the case.


I got it for one part it has, a visible light detector. Any change in visible light, such as turning on a lamp, or just waving your hand in front of it sets it off.
I assume it’s a kind of variable resistor.
It’s extremely sensitive, so quite unlike the photo-sensitive resistors in the supply cabinet. It has a lens rather than a filament.

It’s fun to be able to take stuff apart and now actually be able to identify the components.




Resistors: 10

Transistors: 4

Capacitors: 4 (2 big, 2 little)

1 LED, 1 switch, 1 speaker, 1 light detector

Whoever made this used the technique of using a little hot glue to hold some of the bits together.


I owe Steve Oh a new set of jewelers screwdrivers after I stripped the heads off of his trying to take apart a cd player.


After last week’s “incident” when I blew up a 7805, I rearranged my power input to run with + on the pin rather thon on te sleeve.
So now I can use the DC power supplies at school.
I also got a power supply that let’s you switch between polarities, select from 3, 4.5, 6, 7.5, 9, or 12 volts.
It also can switch between 100 and 300 milliAmps, just in case.


In 1832, New York University was founded.
Of note, it was the first university in the United States to have a fine arts program.
Until then, schools only taught classics, literature, and science and humanities.
The first professor NYU hired for it’s new department was a man named Samuel Morse.
While teaching out of a room in the northwest corner of what is now the Grey Museum, Morse invented the telegraph.
In some ways, the telegraph was a more significant invention than the Internet, since the telegraph was the first, the very first technology that allowed people to communicate in real-time while not actually being face-to-face.
I had no idea that NYU had this kind of legacy regarding the bridge between technology and art, specifically someone coming from an art background and creating a technology (not just a device) that was truly useful, and the forebear of everything related to the Internet today.


Step 1:

Get a DC motor that runs on low voltage DC, in the 5-15V range. Connect leads to its terminals, and run if from a benchtop power supply in the lab. Try changing the voltage on it, and seeing what effect it has. Don't go over the motor's rated voltage. Connect a switch in series with the motor and use it to turn on the motor.


I’ve been scavenging motors from the junk shelf since we started 6 weeks ago, so now have a bunch from which to choose, although I don’t know their voltage ratings.
They all seem to run fine from 2 AA batteries, which is only 1.5 volts.
They run on 12 volts as well, although super-fast, and I get that nice whiff of ozone when I power them up.
Looks like higher voltage means higher speed.


If you want to use flux when soldering, you can just use ear wax instead. It’s cheaper, and chemically identical.


Step 2:

Connect the base of a TIP120 transistor to one pin of your BX-24. etc.


The tip120 has its pins arranged as follows: BCE, so pin 1 goes to the chip.


I need a 1N4004 diode. While a transistor has three pins, NPN, and acts as a switch, a diode has 4 pins, PN, and acts as a valve.
I suppose I could use a ‘light-emitting’ diode here, but I have the real McCoy, so… but which way is up? Fooling around with an LED tells me that the silver stripe needs to go on the ground side of the diode.


Get the motor hooked up, using a pot instead of a switch, seems okay, but my motor sounds like it has a plegm-y throat, maybe it’s half-way burnt already.

Using a 9v battery to power the motor.


When I was working at PC Magazine, I wrote an article titled, “You don’t Know your ASCII from your Elbow.”


Can’t really tell what’s going on in the photos in the web instructions, but I hook up my pot to pin 8, and have a program to turn on pin 13 (the tip120)

 
Sub main()
	call delay(0.5)  ' start  program with a half-second delay
	call putPin(26,1)
 
	do
		call putPin(13, getPin(16))
		debug.print cstr(getPin(16)) ; " - "; cstr(getPin(16))
	loop
end sub

It works: whenever the switch is on, meaning pin 16 is grounded, the motor shuts off.


But now I’ve been through 3 9v batteries – they run for a minute or so then shut off and I can’t get them to work again.
But the multimeter says they’re okay.
I try with a pair of AAs, and that seems okay, but now the motor runs regardless of the tip120. Hmm…


We’ve got quasi-CS with ICM, and quasi-EE with IPC, but I think ITP needs a quasi-ME class.
Something that covers pulleys, levers, and how to mount these motors so they don’t fall off as soon as they turn on.


I skip the batteries altogether and run power to the motor from the 12vDC input, in parallel with the 7805.
Now the motor pulses, exactly 76 times per minute – hmm…
The switch-controlled part works fine, though.
I take out the diode, put in backwards, makes no difference.
Why the hell is it pulsing! I take out the print line in the code, so the only thing the chip is doing is controlling the transistor switch, but it makes no difference.
It must be a function of the ac power coming from the 12vDC power input – but wouldn’t that cycle at 60Hz? This is cycling at about 1.27Hz

I’ve got it. Each time the motor turns on, the power load leaves the chip with too little current so it shuts off, which shuts off the tip120, which shuts off the motor.
Once the motor shuts off, the chip has enough power to start again, etc.


Clara Williams and Jeff’s marionettes at 80 Arts have a blurb in this week’s New Yorker. Movies must be a hot topic for a theme issue – I’ve never seen so many fold-outs and insert ads.


I’m having trouble this week. I can get the bx to switch the motor, and I can get the motor to run, but I can’t get the two together.
I think the battery (now, a new one) is too powerful and is overriding the transistor, which is switched off, because pin 13 is 0.

I wonder if I have the transistor set up backwards, with the emitter and collector swapped, so I switch the connections, and… nothing changes. The motor still ignores the transistor.
Check with the multimter, when switch is off, no voltage going across transistor – thus “off”, right?
Then turn switch on, and I have 5v going across the transistor – thus “on”.
Oh, I’m an idiot. All I had to do was look more closely at the schematic.
I had the motor going to ground instead of to the collector, along with the diode.
Works now.

 
Sub main()
	call delay(0.5)  ' start  program with a half-second delay
	call putPin(26,0)
 
	do
		debug.print cstr(getPin(16)) ; " - "; cstr(getPin(16)) ; " - "; cstr(getADC(15))
		if (getADC(15) > 0) then
		call putPin(13, getPin(16))
		end if
	loop
end sub

I have my light-sensor from the little space-shippy thing on pin 15.
I have a switch on pin 16, and a pot connecting the battery to the motor, so I have pretty good control.
The motor has a fan plunked right on it, and the motor is held by a rubber band.

It occurred to me to make a hovercraft, but I couldn’t get anywhere. Maybe some wheels.


Actually, the code above is too sensitive, and any ambient change in light in the room sets it off, so I set it to 50



Matt Slaybaugh
ms171 at nyu.edu

Categories
Making

Blogma Week 5

Blogma

 
Intro to Physical Computing
Fall, 2003
Jeff Feddersen

Week 5


For next week, I built the light saber in the picture in the upper left.
I think the switch is bad, since the plasma field charge isn’t arcing all the way.
I’ll never take my light saber to the beach again, I can tell you that.
So, I won’t be able to cut off any arms just yet – I can just barely trim my fingernails with it.


I found a 10-watt speaker in the junk pile, but it doesn’t work. The large red ‘X’ that someone had written on the back should have been a clue.


I swear there are two Japanese guys named Koichi in our class, but neither of them has heard of the other. That’s crazy.


It’s time to play with freqout – I don’t even know what the assignment is yet.


I prefer:
call putPin(13,1)
more than:
putPin 13,1


Using ‘call’ and parens makes it easier to find those commands when scanning through many lines of code.


If I wire in a resistor between the pot and ground, my minimum signal is around 164. I want the full range, so I’ll remove the resistor.


It’s a pain to have the basicX manuals in PDF. That format doesn’t lend itself to searches.


I put in the following code:

 
Option Explicit
dim potVal as integer
Public Sub Main()
	call delay(0.5)  ' start  program with a half-second delay
	call putPin(26, 0) ' illuminate green on-board LED to show that power is on
	do
		potVal = getADC(13)
		debug.print cstr(potVal)
		call freqout(20,440,potVal,200)
	loop
End Sub

It should play a pulsing chord composed of ‘A’ and a second note somewhere between the bottom and somewhat more than an octave above A. (One full octave would be 880, adjacent octave leaps are always half or double).

It’s really easy to completely wipe out all your code with this editor.
For the longer projects I’ll probably use TextPad and paste it in when I’m ready.

The bx doesn’t like to download this program, but after flipping the power a few times it learns to become obedient.

Sound! It’s pretty freaking obnoxious, but works.
The volume goes up as the pitch rises.
I first thought that was just an accoustic anomaly, since our cochlea are more sensitive to 1000Hz, rather than say, 5Hz, which is indetectable
– but, it’s not that.
Just having the pot turned all the way means more current going into the chip, which means more available to the speaker, I guess.


I try this code:

 
	do
		potVal = getADC(13)
'		debug.print cstr(potVal)
		tone1 = potVal
		tone2 = potVal * 2
		call freqout(20,tone2,tone1,200)
	loop

Freqout doesn’t seem to like to have arithmetic in the parens.
This should play a note and the same note one octave up, but I can’t really hear whether it is or not.


The highest note I can hear is probably around 16kHz (I’m not as young as I used to be), so if I map 1023 to 16,000 I should get the whole range.
I think 15x should be a good amount.

 
		tone1 = potVal * 14
		tone2 = potVal * 15
		call freqout(20,tone2,tone1,250)

This plays two notes an octave apart, at the top of the range. Okay, I got it. Now it’s time for multiple instruments. But is there a way to use this as a mixer? Or is that just physically combining signals?

Man. It’s that easy. I have pin 20 playing 2 tones, and pin 19 outputting two more.





Mixing signals seems to be just physically wiring them together.


After playing around with the pitch and interval, I got it sounding just like my alarm clock in the morning. I have the urge to smash it.


 
		potVal = getADC(13) * cInt(Timer)


That’s kind of cool – interesting rhythms. You can also put a varying variable (duh) in the duration area. Kind of interesting.


This language uses the backslash ‘\’ for division, That’s wack.


I recently found out that the company where I consult, ACM, owns the whole Siggraph show. I wonder if I could get a free pass to next year’s show.


I could program this thing to play a song, but that would be very tedious and not very impressive. I could make a little keyboard, but I already know I would do it, so the fun part is already over.
Maybe it’s time to start making a mobile robot. But every time I try connecting a motor, there’s not enough power. I have three little motors, but none have voltage or wattage information.
I’m guessing they take between 5 and 9 volts, since I can run them off a 9-volt battery.
Variance in current would then affect rotation speed, I suppose.
I’ll try the servo motor, like in the exercise – another trip to Canal St.
Or maybe I’ll scavenge one of the stepper motors from one of the drives on the junk shelf.


Answering machine comes through again. I tell ya, this one $10 home appliance provides more useful bits per cubic inch than anything else.
It has a little motor for spinning the tape that runs on as little as 1.5 volts.
It was held in place by two of the tiniest little screws I’ve ever seen.
Little baby screws. Their diminutive size made me want to care for them, raise them into big strong bolts like their dad.


I just got a call from a contact in midtown. They’re sending a messenger to my apartment right now with a set of audio cassettes. Someone needs a digital copy made asap.
I’ve never been asked to do this before, but it’s funny how one gets a reputation as ‘the tech guy’.
I never even owned a computer until two years ago.
I don’t have an easy way to get an analog signal into the 1/8″ stereo jack in my computer, and it occured to me I could probably just make some kind of cable to connect a walkman to the input.
I’ll figure something out.

GoldWave and Blaze Audio Wave are really good audio tools (for Windows, anyway).

It sounds like a recorded telephone conversation, so digitizing at 8bit, mono, 11kHz doesn’t reduce the sound quality in a noticeable way.
There are two 90-minute tapes, so I guess I’ll spend the next 3 hours riding the gain.

They’re labeled simply, ID#2778448.

You can hear one guy’s AIM client beeping every now and then.

And another guy has traffic noise on his end – sounds like Manhattan.

But the address on the package says, “xxxx Oxford Street | Berkeley, CA | xxxxx-xxxx”

Nothing sounds too incriminating yet – no gun shots, anyway, or reference to WMD.

They keep talking about SIP. That must be code for something.


I ripped up my umbrella for my spatial design class. The ribs of an umbrella are really ingeniously put together.
They move somewhat like birds’ legs. I’d like to set up four umbrella ribs with motors to make a quadraped-bot, it could carry around my IPC case. I’ll work on it. The mechanical engineering of the ‘hips’ will be the hard part.


Whoa, over 100 total minutes of audio in just 12MB of file space. The people who came up with MP3 should get some kind of award.
When I did digital video back in ’94, we had to buy 3 9-Gig drives, each the size of a toaster oven, for $4,500 a piece because even cruddy 640×480 video took up a megabyte for every second of video.
People talk about how the Internet has changed everything, but I think they forget that the tremendous increase in capacity and decrease in cost of storage over the past 10 years, as well as improvements in compression algorithms, are what has made a lot of ‘new media’ possible. I guess I show my age by putting new media in quotes.


In the Lingo class, I made some crack about the word ‘kludge‘, about how it was a Russian word that defined the way everything was done over there.
Then, Eugene, who is from Russia, says, ‘Is not Russian word.’
I have some Ukranian friends, who use the word ‘kludge’ a lot, and they told me it was Russian, but those two countries went through a messy divorce a decade or two ago.
I’m going to hang out with them tomorrow night. They’re fun, but man, can they drink.


Two years ago my first textbook (“Professional Web Graphics”) was published. I’ve been getting royalty checks each March and September since then.
That would be cool, except that the last check was for $697.77! 10% my eye!
If you are ever in a position to write a textbook, make sure you have an MD first.
Those guys get, literally, $100,000 just for the advance.


A few weeks ago, I was thinking about how cool it would be when we finally got into music stuff in IPC. But if the puny freqout is all there is, then I’m more interested in robots, maybe building one of those AT-ATs from Hoth.
On the other hand, if I wire up a humbucker or two…
Those are essentially variable resistors, right?


And suddenly, the paradox of political correctness becomes clear:
How can you embrace all cultures if some cultures don’t share the idea of embracing other cultures?


So I take apart an electromagnet I pulled from some kind of executive office desk toy, hook up the multimeter, and pass a magnet by the rod in the center. Sure enough, there’s a voltage – very small.
I put one lead in pin 17, and the other in… where? ground? okay. No, that’s not it, I just get full-on 1023.
It doesn’t seem to matter how I wire it up. I got a reading down to 46 at one point, but plucking a guitar string near the electromagnet didn’t have any effect.
Darn, I know I’m close.


I missed the flügtag on Sunday as I was stuck in Brooklyn.


I’ve been to about 10 hardware stores this week, looking for servo motors – but found only steppers.
It looks like we get into regular DC motors next week, so I’ll do the motor stuff then.
I think steppers will be more appropriate for robots anyway.


It looks like a more solid understanding of Ohm’s Law and the relationship between power, current, and resistance will be necessary as we get into more complex circuits.


I’m not sure I agree with the ITP philosophy of pandering to students who are bad at/afraid of math.
Some problem sets where we fill in the blanks on circuit diagrams would be useful.


My final program (back to just messing with sounds)

 
Option Explicit
 
dim potVal13 as integer
dim potVal14 as integer
 
dim tone1 as integer
dim tone2 as integer
dim tone3 as integer
dim tone4 as integer
 
dim rate1 as integer
dim rate2 as integer
 
Public Sub Main()
	call delay(0.5)  ' start  program with a half-second delay
	call putPin(26, 0) ' illuminate green on-board LED to show that power is on
 
	do
		potVal13 = getADC(13)
		potVal14 = getADC(14)
 
		tone1 = potVal13 * 2
		tone2 = potVal13 * 4
		rate1 = potVal14
 
		tone3 = potVal13 * 8
		tone4 = potVal13 * 16
		rate2 = potVal14 \ 2
 
		debug.print "tone:" ; cstr(tone1) ; " " ; cstr(tone2) ; " " ; cstr(tone3) ; " " ; cstr(tone4)
		debug.print "rate:" ; cstr(rate1) ; " " ; cstr(rate2)
 
		call freqout(20,tone2,tone1,rate1)
		call freqout(19,tone4,tone3,rate2)
	loop
End Sub

Two pots, one in pin 13 and one in 14, acting as voltage regulators.

#13 controls the pitch, and I’m getting 4 tones out of it, ranging from 0Hz to about 16kHz.

#14 controls the duration, ranging from 0 to about 1 second, with a second duration exactly half the length.

Pins 19 and 20 both connect to the speaker, which connects to ground.

It’s clumsy, but it’s possible to play simple songs on it.



Matt Slaybaugh
ms171 at nyu.edu

Categories
Making

Blogma Week 4

Blogma

 
Intro to Physical Computing
Fall, 2003
Jeff Feddersen

Week 4


No funny business this time. Just work. All sentences. In fragment form.


Dan got eggs and bacon at deli Friday morning.

I coveted his breakfast.

But why were the eggs so yellow?

I mean: Yellow.


Forgot case, breadboard, and BX chip in room 406 Friday morning.

Returned over 6 hours later only to find everything exactly where I left it.

Faith in inherent goodness of mankind renewed.


There are 10 kinds of people in the world: Those who understand binary, and those who don’t.


Stuck around to hear Todd’s presentation. Stuck around longer to salvage parts.
Found disassembled (disembled?) VCR in junk pile in shop area, or whatever that room is called.

Included in it were push-button switches (push: on, push again: off).
Scavenged 4 or so by melting the solder off the underside of the board. Burned myself twice.

Learned to be afraid of the Knights of the Temple and the Freemasons.


QOTD: It just isn’t fun until something explodes.


The BasicX software interface takes like, SIX full minutes to start or stop the chip.
What the $%#!


Jeff mentioned a trick in class (awesome presentation on the sound/voice stuff, btw) for when you’re getting comm errors:
While the software is trying to re-establish communication (1 to 20 times) just power off and on quickly.


I tried it. It works.


Step 1:

"Wire LED’s to pins 13-20 of your BX-24. Use the same digital output circuit from the previous lab. Write a simple for-next loop to light them all in sequence"

I would have written the code myself, but it’s right there on the site, so I will C & P.

 
Sub main()
dim nextLightVar as byte
 
	call delay(0.5)  ' start  program with a half-second delay
 
do
	for nextLightVar = 13 to 20
		call putPin(nextLightVar, 1)
		call putPin((nextLightVar - 1), 0)
		call delay(1.0)
	next
loop
end sub

I tried it. It works. I only put in LEDs for pins 13 through 17, so there is a extra few seconds before the cycle repeats.
The chip is busy turning on three pins that I’m not using.


I would take a picture, but a still photo doesn’t capture the magic of this… this… sluggish theater marquee.


/,’;\[=`?<":|{+)*^$@~.]+_)(*&^%$#@!~~|}{?><":|}{


This string of obscenities uttered in an early Popeye(©) comic strip from 1931 is coincidentally the exact line of shell scripting that allowed Kevin Mitnick to access the Norad computers in 1983.


Step 2:

"Wire a switch to pin 5 of your BX-24. Use the same digital input circuit from the previous lab. Wire an LED to pin 20. Write a program that stores the state of pin 5 in a variable, and changes the LED based on that variable."

Okay. Again, this would be more challenging if we weren’t given the answers. I’ll use the code from the site.
I’m using a pot instead of a switch, and one of those big fat yellow LEDs on pin 20.

 
dim switchVar as byte
 
Sub main()
	call delay(0.5)  ' start  program with a half-second delay
 
do
	switchVar = getPin(5)
	call putPin(20, switchVar)
loop
end sub

If I put the LED in one way, with the long end (anode, right?) taking juice and the short end (cathode, right?) in pin 5, it works fine.
Or I put it in the other way, with the long end in ground and the short end in pin 5.

The two ways were in the reading, and Jeff went over it again in class – The pins can blow 15mA, but can suck 20. So there you go.

Again, no pictures. I mean, what would a photo of an illuminated LED say to you?


Saw Philip Seymour Hoffman on the street today (Washington Square West) pushing a stroller. The kid was not cute.


Here’s a paper on using a grid of LEDs in place of a standard CRT display:
http://www.ee.calpoly.edu/~dbraun/papers/ICSM2000BraunEricksonK177.html

(no, I didn’t read it either)

But this page has a useful explanation of LEDs.
This would be useful for Maia’s digital display project.


Christina is trying to solve the world’s transportation problems with a ball that rotates independantly in all three degrees of rotation.


Red Bull, the ‘energy’ drink is sponsoring a flügtag at pier 40 on the Hudson on October 5. Christina should enter. Hell, ITP ought to have a team!


I notice there isn’t much communication between the second-year students and the first-years. Just like at Hogwarts. Yes. Just like that.


I am not a number, I am a free man!

But all the same, I am in group #6.

Matthias, Koichi, and I have come up with a topic.
In six weeks, I will say, “You may now replace the socks that have been knocked off”.


Step 3:

"Write a program that counts the number of times the switch has been switched on, and puts it in a variable:"

 
dim switchedOnVar as byte
 
Sub main()
	call delay(0.5)  ' start  program with a half-second delay
 
do
	if getPin(5) = 1 then
		switchedOnVar = switchedOnVar + 1
	end if
	debug.print cStr(switchedOnVar)
loop
end sub

Okay. Even when the pot is cranked all the way to the other side (this is one of those taper pots, mind you) – there’s still enough juice to register the pin as active.

So, I make a switch, a la Steve Oh, which is just two twist-ties stuck in the board.

Here we go.

Yes. It keeps repeating, and starts over once it gets to 256 (or 255? Does it count from zero or one?)

"Why does the counter run so high? How can you make the variable increment only once per switch press?"

Now here’s a problem I like: a little logic puzzle.

This reminds me of the GRE.

All you have to do is add a variable that registers whether the switch is on or off.

Perhaps the following code would help illustrate:

 
dim switchedOnVar as byte
dim counter as integer
Sub main()
	call delay(0.5)  ' start  program with a half-second delay
	do
		if ((getPin(5) = 1) and (counter = 0)) then
			switchedOnVar = switchedOnVar + 1
			counter = 1
			debug.print cStr(switchedOnVar)
		end if
		if (getPin(5) = 0) then
			counter = 0
		end if
	loop
end sub

It only increments the variable once when the switch is turned on.
The switch must be turned off and on again before it will increment again.


My yelow led shines bright(ly)

You know why?

Because it’s my Beacon of Hope


Did you hear that Robert Palmer died?
I wasn’t exactly a fan, but my brain can’t help but remembering lyrics such as:
“You like to think that you’re immune to the stuff. Oh yeah.”
“Closer to the truth is that you can’t get enough. You’re gonna have to face it you’re addicted to love.”


Step 4 (optional step):

Connect 8 LED’s to pins 5-12 of your BX-24. Run the following code to see the binary contents of a memory register reflected in the LED’s:

 
Sub main()
	call delay(0.5)  ' start  program with a half-second delay
 
	dim counterVar as byte
	register.ddrc = bx1111_1111
	register.portc = bx0000_0000
 
	do
		for counterVar = 0 to 255
			register.portc = counterVar
			call delay(1.0)
		next
		call delay(3.0)
	loop
end sub

Okay, the leds should light in sequence, based on the curent register, which I’m incrementing with each loop.
It’s too slow, so I’m commenting out the delays.
Hmm. I’ll put them back, and add this line

 
debug.print cStr(counterVar)

The leds are on all the time, but change in brightness. However, I always forget which end is + and which is -, so I’ll switch them around.

I think the problem is that all the leds are too close, and the metal ends come into contact. But I get the idea.


Why doesn’t ITP have classes in music?

There are three disciplines that combine math and art:

  • Music
  • Architecture
  • New Media

Jean-Marc Gauthier covers architecture, how ’bout some music theory classes, hmm?


Step 5:

    Practical Joke, eh? I could:

  • Cover it in dog poo, set it on fire, put it on the floor outside Tom Igoe’s office, then knock on the door and run away.
  • Tap it on the left shoulder, but I’m on the right, then when it looks – no one is there
  • Do the 5-timing switch thing.

I’ll pick one randomly.


I want an oscillator so I can start making sounds. Here’s a page on oscillators


I found a diagram to make an oscillator just out of resistors, put in proper order. It looked a little too complicated to try. Maybe later.


You know who has a cool name in our class? Luna Vega

Her first name is the moon, and her last name is a star.

When I was in college, one girl was named Victoria Zeppelin.

Apparently she was a descendant of the original Baron Von Zeppelin, after whom the airship and the subsequent rock and roll band were named.

I knew her boyfriend.

He was a jerk really swell guy.


Solder iron burns start out as white, then turn to dark mauve.


 
Sub main()
	call delay(0.5)  ' start  program with a half-second delay
 
	dim switchCounterVar as boolean ' is switch on or off
	switchCounterVar = false
	dim counter as integer ' how many times has switch been turned on
	counter = 0
 
	do
		if ((getPin(12) = 1) and (switchCounterVar = false)) then
			switchCounterVar = true ' yes, pin is on
			counter = counter + 1 ' increment counter
		elseif (getPin(12) = 0) then
			switchCounterVar = false ' switch is off
		end if
 
		debug.print cStr(switchCounterVar)
		debug.print cStr(counter)
 
		if (counter > 4) then
			putPin 13,1 ' turn on pin
		else
			putPin 13,0 ' turn off pin
		end if
 
	loop
 
end sub

This the ‘practical joke’, requiring the user to turn on the switch 5 times before the LED lights up.
I tried the dog-doo approach, but Midori yelled at me.

The hardest part about this is remembering that comments are indicated with an apostrophe, rather than a double hyphen (as used in Lingo).


The Empire State Building used to always turn off their lights at midnight, but lately I’ve noticed that they leave them on until 4am or so.
I’ve only noticed this since the blackout a month ago.


The Third Matrix preview is out. The second one was kind of disappointing, but it’s still cool.


This is a robot site. They are hiring.



Okay, this is cool. In my readings I see that to make sound come out of a speaker, I need an amplifier.
And the signal could be from a microphone or from an oscillator.
But, the most basic amplifier is just a transistor, and an oscilator is just an amplifier with some kind of feedback loop.
So, if I stick a transisitor in the board, I should be all done, right?

So I stick a mic in the board, one end getting red sauce, the other end in the middle pin of an NPN transistor.
The speaker also gets red sauce, and its other end is in the right pin of the transistor.
The left pin of the transistor goes to blue ground.

I switch on, and sure enough, I have a PA system. It’s not loud, but I can hear myself in the speaker when I speak into the microphone.

So, now I want some feedback, so I stick a wire in that connects the input and output on the transistor. Right away I get a hum, the pitch of which is like that of fluorescent lights, a few hundred Hertz – definitely more than the 60Hz that is the frequency of electricity from the wall (in this country).

I want to vary the frequency to make different pitches. I try sticking a pot into the mix, and while I’m able to make a working volume control knob, I’m just varying the amplitude, not the frequency.
If I throw some resistors and capacitors into the mix (specifically, within the feedback loop) I might have more luck. But that will be for the future.



I hooked up two transistors with a resistior, and now get a buzz sound of a higher pitch than the one before.
The weird thing is, if I simply touch the paper cone on the speaker, the sound stops, but if I tap the metal frame of the speaker, it starts again.
And if I lightly press the edge of the paper cone, I can make the pitch rise.
None of this makes sense. And if I move my hand over the speaker without touching, the pitch drops. Totally weird.
The buzz is probably completely a function of the size and shape of the paper speaker cone, rather than the frequency being sent via wires.


Stephanie says I look like ‘The Commish’. Oh man. I realize that I have very little hair, but why not Bruce Willis? Or what about Benito Mussolini? Now, there was a guy who ‘got things done’.


Found numerous diagrams on the Web for ‘astable multivibrators’. The schematics look easy enough, just cross a pair of capacitors and two pair of resistors.
But I couldn’t get it to work. However, I haven’t been looking at the numbers for any of this, and that could be the problem.


I read that a dial tone in a telephone is 440 Hz, the standard ‘A’ that is typically used to tune musical instruments.
I tried to match the tone by ear to notes on my keyboard, but the dial tone sounds more like a ‘C’ and an ‘F’ sounding together.


The speaker is getting really hot in my ‘telephone’ setup, the magnet part anyway.
The multimeter reading says it’s getting around 22 volts – can that be right? And 5 ohms of resistance, that would explain the heat.
I also get a reading of 1.25 volts AC. Can that be right? I took out the feedback loop, so there’s no cycling signal, which I imagine would register as AC.
No wait, that wasn’t AC, that was ‘DC A’. I don’t even know what that is.

That was the baby speaker. When I put in the mondo speaker, the signal seems a little louder, but that may just be because the larger speaker can handle a larger bias – range of sounds – especially the bass.
The mondo speaker is getting 5 volts. That seems right. And 12 ohms across the terminals. If v=i*r, then the current, i, should be equal to 12/5, or about 2.4, uh, milliamps?
The numbers don’t change when there’s an active signal (me whistling into the microphone). I figured I would have seen something fluctuate.


When I put the feedback loop in, and match it to my keyboard, I get A#. That’s odd.

Here’s a diagram of a basic transistor amplifier.
Let’s try it.
Nope. Nothing. Here’s another but that looks more complex.
Geez, so may designs, and all different. And none work as well as skipping all the capacitors and resistors altogether, and just linking a mic and speaker via a single transistor.


Soldering speakers is challenging because the magnet is always trying to pull the iron toward itself.


Have a third speaker, middle in size, rated at 8 ohms, 0.2 watts. The big one is 3 watts.
Watts = volts * amperes, so 3w = ?v * ?a
Umm, my math says that the current would be the square root of 3/8. Who knows.
Mulimeter says it carries 35 ohms. That can’t be right. That’s not even the right significant digit, let alone which factor of ten it is.


Solder is obsolete.


Microphones and speakers are basically the same thing, and I’ve used headphones as microphones in the past.
I plug in the middle speaker in place of the mic, but just get buzz, no voice.
But this time, manipulating the big speaker doesn’t give me the variation in pitch like it did before.


Matt Slaybaugh


ms171 at nyu.edu

Categories
Making

Blogma Week 3

Blogma

 
Intro to Physical Computing
Fall, 2003
Jeff Feddersen

Week 3


I had been invited to the beach where friends have a cottage this weekend, but said no because I had planned to go upstate to see other friends – but now they’re all sick, and the beach friends are already gone.


So I’ll spend Saturday haging out with some wires.


I was a little concerned when Jeff pointed out to that one girl (Italian, dark hair, what’s her name?) that her circuit was put together in such a way that the 12 volts from the main power supply was feeding into the 5V loop she had made with the regulator.


I think mine may have been the same, so I pulled out everything and started over.


Have you seen the BasicX Customer Applications page?


People are using this thing to control personal helicopters, rockets, and freaking satellites!


Dag, if they can do that, my dream of having an army of robot minions is closer than I thought.


Those wires with the many bundled threads (instead of one thick one) are a pain in the butt to stick in the bread board. But you knew that. It helps to twist the ends. It doesn’t help to use solder as an adhesive – you end up with a glob of solder and the wire won’t fit in the board.


I used to work at the United Nations, and there was a time, during the lull between the Afghanistan and Iraq invasions, when my boss was leading a program to rebuild schools in Afghanistan.
He had some meetings with President Bush and others, to see if the US and UN could work together to gather, ship, and deliver supplies and personnel.
The plan never materialized in a significant way (although millions of American schoolkids donated pencils for the cause).
I asked my boss what Bush was like, since I had never met anyone who had actually spoken with him.
My boss said, “He’s just as stupid in person as he is on TV.”


I believed him.


I got the bx24 in place and got the leds flashing, with the proper power, but then realized I had skipped the switch, so back again.


I brewed a new batch of beer this weekend, a Canadian red ale. My brown ale from last week got some contamination, so has a sour taste, like a porter.


What would be cool is a beer fountain. Once a week you put in water, malt, and hops. The machine has a living yeast culture, and is set up to brew the beer and keep it airtight.
On the front is a spigot for pouring, or even the kind of tap on water fountains.


The switch is in, and,… no leds. Ergh.


I spent some time in Japan over the summer, and saw an exhibit at the Osaka National Museum by a guy named Kenji Yanobe.
It’s awesome. Most art sucks, but this is cool – robots and cars, and radiation suits.


Okay. I had the ground from the bx going into the blue bay, but nothing else was connected to the bay. So I attached the regulator ground to the bay, and:





Well, you get the idea.


Next, the serial thing.


I had some rosemary chicken last night.

It was pretty good.

Do you know what makes food taste really good?

A lot of salt and grease.


Dang, it’s hard to solder the header onto the serial connector without getting gobs of solder everywhere.





You can’t really see it, but the red arrow points to one long glob of solder that unfortunately connects all the leads together, making the whole thing useless.
Trying to melt it off with the iron just made it worse.
I’ll have to… Oh. I see I put the header in backwards, so the black plastic bit was getting in the way.
I’ll try again.


This site has a good explanation of everything related to physics – electricity, music, etc.


Wow, unsoldering is worse than soldering.
The whole thing is nearly trashed, because the iron melted the white and black insulation.
But fortunately, solder seems to have pretty high surface tension when melted, so it wants to clump together, the way water beads up on a waxed car hood – so there is a technique for ‘herding’ stray bits of solder away from the contacts.


If we get into music, I want to fool around with the different kinds of temperaments.
Most Western music is based on the ‘equal-tempering’ scale, but that differs slightly from the Pythagorian and Just tempers.
The one we use now (Equal Temper) is mostly used out of convenience in transposing songs from one scale to the next.
but in my opinion, the Just temper sounds more natural. The Pythagorian and Equal tempers may be more mathematically symmetrical, but are sort of artificial.


Jeff said don’t use the soldering iron to make holes, but I have my own iron, and I will. A little sandpaper takes off the crust fine.
Anyway, a girl I used to know still has my drill (that sounds like a song) and I’m not sure how to ask for it back.


It turns out it’s easier to just pop out the ventilation slits from my answering machine case, so I’m doing that.
The connector has screw holes. I’ll try to use them.




This is the back of my case.


You can see the power connector on the left, the switch, then the serial port on the right.


You can see how the switch and port are installed where the ventilation slits used to be.

Hmm. This camera seems to like bright light.


Those hardware companies we looked at on Friday reminded me of when I was a camp counselor. There was one kid who wore the same t-shirt every day, a green one with a huge logo for ‘Bob’s Surplus’ with ‘surplus’ in huge letters. His dad owned a surplus hardware store in New hampshire.
On the first few days of camp, we would always have a hard time remembering kids’ names, so would often just say ‘freckles’ or ‘blue shorts’ or whatever. But everyone started calling this kid ‘Surplus‘.
It was one of the only nicknames that stuck throughout the whole summer. It’s a good nickname.

On the last day of camp I asked Surplus if I could have his shirt, but he made me pay a dollar.

I still have the shirt.

It still stinks like BO


Well, the connector is screwed in tight, but now the leads are inches from the bx. I’ll have to rearrange everything to be neater. I don’t like having lots of wires looking like spaghetti.


It’s tricky to get the bx out, but fingernail clippers to the rescue again – the file is just the right size to pry it out without damage.


OUCH! Soldering irons are hot! Stupidgoddamnmotherfuckingpieceofshit!


There’s a gap between the cip on the board and the serial connecter on the wall of the case. So I’m wiring two headers together.
I think this must be the hard way. Sometimes the hard way is the right way, and sometimes the hard way is the stupid way.
I’m not using color coordination for the wires, but at least I have 4 colors.


When I was a DJ at WVBR, the station was held together in many places with scotch tape and paper clips.
The engineer was always tinkering with some dusty piece of crap, and he always had a cigarette in his mouth.
But I never saw him light one, and I never saw him put one out, and I never saw him flick off the ashes.
One time I was having trouble with the board – one of the sliders wasn’t working.
The engineer came in and had about two full inches of ash at the end of his cigarette.
While we were on the air, he simply lifted up the whole control panel, exposing all the wires and switches, as well as lots of dust bunnies and old gum.
He poked his head in, and poked at something, then shut the panel, and as he did, it hit the ash from his cigarette, knocking it into all the electronics.
He didn’t seem to notice, and I didn’t say anything.
He told me that it wasn’t working (oh, thanks) and just to use the other bays (I was doing that anyway).
But after he left, it worked fine.


My soldering technique is improving. The bundled-thread kind of wire sort of soaks up the solder. I wish I had a third hand though. Or a robot minion.


Myron Krueger says about nanotechnology, “It is also necessary to produce an aesthetically pleasing interactive experience which both the human and the bacterium enjoy.”

What a putz.

Bacteria can go screw themselves.

If they’re asexual, then I suppose they’re doing that anyway.


Time for a break. Maybe I’ll shave. It’s been a week or two.
At my old job I was always the slob for not shaving.
But next to some of the people at ITP I’m Mr. Personal-Grooming.


I’ve sometinmes been pinching the wire ends with needle-nose pliers to kind of crimp them.

The pliers are rusty and some rust mixes in with the solder.

I know iron is conductive, but is rust conductive?

Multimeter says: no.


In college, I paid $300 for a 1977 Chevy Malibu. It was a piece of crap, and the fact that I had a serious accident 15 minutes after picking it up from the guy’s house didn’t help.
But it had those long bench seats in the front and back.
I wish cars had those now





Connections done. The red arrow points to the connector, yellow to the leads into the bx, and green shows the regulator.

So much for my ‘no-spaghetti’ rule.


And now – the software…


I’ve got WBGO (88.3 – 24-hour jazz)on the radio.


Newark sucks, but they have a good radio station.


Hook up BX to serial connector – check

Software installation – check

Locate 9-pin serial cable amongst my pile of crap – um… wait, I thought… well hell – I thought I had one! I have every other kind of cable known to man (and some unknown…)

I don’t want to have to stop – I’m on a roll!

Fine, I’ll go buy one.

Some time later…

… so then I say, “No! YOU stick it up YOUR ass!” … Wait. What was I talking about before? Oh yeah, the cable.

Male-to-female 9-pin at Staples – $10. Why is service so terrible in New York?


The beer is fermenting, bubbling away nicely. I used some new-fangled kit for my previous batch, but couldn’t get a good seal – so I’m back to my trusty plastic bucket.
It aint pretty, but it does the job.


Plug in the cable, open the software. Hmm. Monitor the port. Port 1, nothing. Hmm. 16 ports total. Try #2 – Hey, there it is!

‘Hello world’.

When HAL dies in 2001, the last thing it should hav said was “Goodbye world“.


My apartment’s a mess.
Between my design class and this one, I’ve got scissors, wires, glue, scrapped electronics, cardboard, random crap all over the place.

At least with the Director class I can just move all the files to a folder, or delete them.
Life would be good with a delete key, or a backspace key, an undo command.

Maybe I should clean.

But after all the time spent getting this BX to work, shouldn’t I be allowed to play with it?

Why, yes.

On pages 81-82 of “The Pleasure of Finding Things Out”, Richard Feynmann describes the disease of computers, the addiction, the “…deligt to be able to see how much you can do.”

That sums it up.


Oh, but when I try to halt the processor I get an error – ‘no communication’. Are the wires wrong?

It must be one of the first two pins since it’s obviously powered okay.

The wiring is right, and no breaks or shorts…

I looked at the Windows System Information panel, and it says I’m using Com 4, 1, and 2.
Under #2, next to busy, it says ‘-1’ – so is that busy or not?!?

I see the Hello World message, so the transfer pin is okay – it’s just the rx that’s not working.

The ‘Getting Started’ doc (so many docs!) says “Configure the
port to 19200 baud, no parity, 8 data bits, 1 stop bit.” Oh. It already is.

I tried again to halt the processor, and immediately the leds stop flashing, but I still get the same error.
And now I can’t start it again!! Oh. Turning it off and on again does the trick.

What the f***?!?! Now I CAN start and stop the processor via software. Maybe shutting it off and on fixed whatever problem there was.
Now I get a new message, a big X made out of the word Basic. But now it says serial data error.

Okay, I think the screws I used to attach the port stick out too much for the cable to make a solid connection.

I’m spending too much time writing – and I haven’t even started the lab assignment yet!


Several hours later…


Okay, less yaking, more hacking.


I used my blue goop to hold the port in place, and let it dry – seems to work.


#1


I’m trying to get the first program to run, and everything looks good, except the LEDs aren’t lighting – oh wait, there it goes.
The example program uses ‘0’ for the value of pin 14, but we don’t want that. So I’m setting them all to ‘1’.
Compile and run – fine.
I only put in 13 through 18, but I think I get the idea.





The code doesn’t need to loop. The pins are live and don’t have to be reset.


I ran out of wire, so I used a little twist-tie from a loaf of bread or something – Absolutely PERFECT. Just the right guage wire, easy to strip off the plastic insulation.
And something about using a little pice of junk instead of throwing it out is very satisfying.


I mean, it’s just wire, but now I can deduct bread on my taxes.


#2


I stuck a little homemade switch in pin 10.


With the switch open I get a value of ‘1’
With it closed I get a value of ‘1’


Pin 11 reads ‘1’ as well. Maybe the switch is bad.
No, because even a single wire gives the same result.
When I close the switch the LEDs get brighter, so there’s definitely current moving, although I don’t know why it would have an effect.


Oh. Duh. I got it.

I tried reading pin 13, after it was lit. The software read ‘0’, and the LED turned off.
So just reading a pin switches it off? That can’t be right.

I’m moving the chip over – I don’t have enough open pits on the left side.


#3


Easy.
I used this:

 
do
if getPin(12) = 1 then
	call putPin(13,1)
	call putPin(14,0)
else
	call putPin(13,0)
	call putPin(14,1)
end if
loop

It has to loop since it needs to always check the states of the pins.

So a switch is one thing. But what if I use a potentiometer? At what point is the pin ‘on’. One way to find out… well, two ways – I could look it up. But this is the better way.


These LEDs don’t seem to need the resistors in front of them. They work fine without.
Maybe Jeff can explain the necessity of them.


So I have a pot switching between pins 5 and 12 and LEDs in pins 13 and 14.
I’m using this code:

 
do
if getPin(5) = 1 then
	call putPin(13,1)
	call putPin(14,0)
end if
 
if getPin(12) = 1 then
	call putPin(13,0)
	call putPin(14,1)
end if
loop

(It’s way easy to compile and run this thing – compared to something like Java.)

Moving the dial lights the LEDs, left for 13, right for 14. Cranking the pot to the extreme makes the LED brighter. That doesn’t seem like something that should happen.


So I still don’t get when the pin is on – when it has a minimum voltage passing in, I suppose.


I tried with three LEDs and one seems to go on later, needing the pot to be turned further. Is that a function of the LED? No, because they’re all that one red kind of the same size.


There seems to be a point in the pot when neither pin 5 nor 12 are getting enough juice. Maybe the minimum is 2V.

I’m looking through the docs – so many docs! among other things, it says the bx24 takes 5.5 V to 12.0 V, but we’re putting in 5.0V, right? Hmm… Oh, but later it says the minimum voltage is 4.8, so I guess we’re alright.
I can’t find anything about what makes the pins ‘on’


#4


Hmm. What’s XbotX, that looks cool.


I dunno what to make, a simple 8-key keyboard would be cool, or even 4 keys – I could play ‘Taps’.


I want to do something cool. I’ve gotten enough of blinking lights.


I tried using little motors instead of LEDs, but I get nothing. Not enough current or voltage.
I tried a little incandescent bulb, too, but nothing.

The syllabus says, “Make an interesting application…” well, I tell ya, it just aint possible to do anything all that interesting.
I could write an app that says, “You’ve just connected pin 11! You ‘ve just disconnected pin 11!” But that wouldn’t be interesting.

Eh. Screw it. I’ve done enough for this week.



Fooling around with the software. Just one level of undo, obfuscated error messages, crashed a few times – not as good as I had first thought.

Getting more communications errors – out of the blue, all the connections seem solid.

Now some of the components (resistors and the regulator) are getting hot.


Unplugging. I’ll try more another day.



More comm errors, so I closed and opened the ports, and now it seems fine.
Still, my CPU maxes out every time I start or stop the bx. I wonder if there’s a runaway process somewhere – an unterminated loop.


I justed tasted my beer – pure vinegar. I guess I could make some pickles, or dye some Easter Eggs.


-sigh- It will be a while before my robot minions are finished. But in the meantime, who will do my bidding?



Matt Slaybaugh


ms171 at nyu.edu

Categories
Making

Blogma Week 2

Blogma

 
Intro to Physical Computing
Fall, 2003
Jeff Feddersen

Week 2

Meat Resistor

When I was a kid, Mr. Wizard was on Nickelodeon and he cooked a hotdog with some apparatus that basically electrocuted it.

I simplified his design by taking the power cord from an old lamp, and sticking the wire ends into either end of a hot dog.

I plugged in the cord and pretty soon the hot dog started sizzling and spitting and cooked pretty quickly.

In fact, I had to run over and yank the cord from the wall when the plastic insulation started to smoke.

It tasted okay (the hot dog, not the insulation), like a microwaved one.

Hot dogs have a lot of salt and water, and salt water is one type of electrolyte, meaning a liquid conductor, I guess.
But all the animal proteins in there aren’t good conductors, they are resistors of sorts, meaning when electrons pass through them they create heat instead of just coasting through.


Canal Street is the place, the palace, even.

Kat said that at 269 Canal is some guy with a whole lot of stuff in the back.

Just walk up to him and say, “Hey man, how ’bout hookin me up with a little som’n som’n?”

Trust me, he’ll know exactly what you’re talking about.

No, seriously, I talked to him and it sounds like he deals with lots of students doing projects, so he should be able to tell you which resistor goes with which capacitor. Just remember not to mix plaid with stripes.


Still to do:

  • Pick up readings
  • Signup for cleanup time
  • Take safety class
  • Complete this week’s project
  • Buy books

(hmm, that’s everything that was on the list last week)

I read The Design of Everyday Things back in college for a class, but I don’t have it on my shelf. I should get it.


Jeff has a thing at the Brooklyn Museum of Art with Clara Williams involving robotic marionettes.

I don’t see anything on the site about it. Maybe I got the name wrong.


There’s a guy from Honeybee Robotics speaking tonight at 6:30 in the Japanese Room.
I almost had a gig at Honeybee last year, but the grant from Nasa didn’t materialize.

I would have just been rebuilding their Web site, not making robots, but it still would have been cool.

Check out their facility if you can. It’s weird to see such an industrial-looking shop floor in the Lower East Side.

Their current projects include the rock-core sampler on the current Mars mission, and some other Mars stuff, and some kind of robot that would build communications satellites in orbit instead of having to deliver them via rocket. Pretty freaking cool.


I took some photos on the cheapest piece of crap digital camera I’ve ever seen.

But for $40 it’s amazing that it does anything.




My answering machine was in bad shape; the messages were almost unintelligible.
I cleaned the tape head, but that didn’t help, so I bought a new digital answering machine and sacrificed the old tape one for Science and Truth.


When I opened it I found lots of dust embedded in the switches and especially the ‘lateral potentiometer’ used for the volume control.
Maybe that was the problem.


It has quite a lot of good bits on it that I might be able to salvage: switches, speaker, microphone, motor, lots of diodes and triodes and I think I saw few quadrodes – not really.




The bread board fits quite well in the answering machine case, so I guess I’ll use that for my housing. The case already has holes for switches and cables to go through.




I had been keeping my keyboard from 1989 for mostly sentimental reasons, since it doesn’t play well now and fixing it would cost more than buying a new one that’s ten times more sophiticated.


So it too is being sacrificed for Science and Truth.
It has some mondo speakers.
I had been keeping it behind my computer monitor, which kept showing weird colors whenever I moved the keyboard.
I guess the monitor uses magnets to align the display of the cathode ray tube, and the speaker magnets messed them up.


Onward and upward. And sideways.


I read a joke on Slashdot:

If it doesn’t move, but it should, use WD-40.

If it moves but shouldn’t, use duct tape.




I soldered the power connecter thing. But discovered my housing didn’t have the right-sized hole to stick the connector through.




Fortunately, soldering irons are good at making holes in plastic. (The blurry area in the center). Watch those fumes, though, phew!


Anyone else notice that fingernail clippers make decent wire strippers? Just don’t clip too hard. You have to feel the difference in resistance between the insulation and the metal.

Actually, plain old fingernails seem to work okay too.


Success!





It looks like everything is working. The LED is illuminated and none of the parts are smoldering or even warm.


“Indescribable joy”? Well, I guess that describes it pretty well.




You can even see the LED when the cover is back on. (I swear this picture isn’t from before I took the answering machine apart.)


Next, the
switch. Stay tuned.


Napalm Adhesive

The problem now is how to affix the switch in the case so that it doesn’t move when the switch is flipped. Even a little give could mean broken solder points.

I want to attach metal to plastic. Glue doesn’t work, solder doesn’t work. Melting the plastic a little doesn’t work. And there isn’t room to use screws.


My solution: get some nail polish remover (acetone, or kersosene or gasoline will do) put a little in a glass bowl or jar.

Get a styrofoam (polystyrene) egg carton, or coffe cup, break it into little pieces and watch it dissolve.

Mix it all up and you’ll have a napalm-like substance. Add more acetone or polystyrene until you have a jelly-like texture.
This is extremely flamable, but also is good for molding plastic, since once the acetone evaporates, you’re left with a hard, brittle plastic.
It’s still styrofoam, just without the foam, since the air is gone.


I used this to mold a shell around the switch, binding it to the case. We’ll see if it works. I’ll leave it for a few hours to dry.


Ugh. In the future, I’ll make sure to use a toggle switch, one that flips. My switch slides back and forth, and it requires a much stronger adhesion to the case.





Step 2 of this week’s assignment is to wire some LEDs in series to see the effects.
The picture doesn’t really show it, but they all get dimmer every time another one is added (a metephor for bureaucracy?)




While placing them all in parallel leaves them all shining bright. In fact one was getting kind of hot, maybe too much of a load.
I notice some LEDs shine in different colors, depending on how much juice there is. That’s cool.


Step three is to add a variable resistor. Okay. Step four is to build a ‘combination lock, a puzzle, a trip switch’.
What?!?! I think I’ll need some more hand-holding before I attempt that.


So put in a second potentiometer (the former volume control of my answering machine) – it’s nice because the leads go right into the breadboard.


The first pot is an audio taper so the dimming from one LED to the other isn’t linear, and the first one never goes completely off.


I guess this now qualifies as an absolute minimum combination lock – imagine a lock with two dials, each of which has only two numbers: zero and one.

pot a position |pot b position |circuit
00off
01off
10off
11on

It works, although I wouldn’t use it to lock up my bike.

From talking to the other students, it sounds like most are still working on getting their first LED to light (and it’s Thursday evening already).
So I guess I’m ahead of the game.


Oh, and you can use a candle to melt off insulation instead of using strippers. The plastic burns off and leaves the metal behind.


Matt Slaybaugh

ms171 at nyu.edu

Categories
Making

Blogma Week 1

 
Intro to Physical Computing
Fall, 2003
Jeff Feddersen

Week 1

Why did I add these images on the right?

Was it just to collect the Amazon affiliate fees?

No.


Monkey vs. Robot is THE metaphor for ITP.

The Monkey represents all that is animal about us – our emotions, intuitions, desires.

The Robot represents all that is intellectual about us – our ability to be analytical, calculating, clinical.

And now they’re fighting!


Solarbotics is a good site from where to order parts.

One 0.47uF Monolithic Capacitor is just 25¢

No way?

Yes way.


Do you know BEAM? It is an idea and an organization started by Mark Tilden, advocating the idea of autonomous robots.

BEAM stands for:

Biology Electronics Aesthetics Mechanics

Building Evolution Anarchy Modularity

Biotechnology Ethnology Analogy Morphology

Why, here is their site to visit.


Apparently, a “Henry” is a unit of inductance.

I bet he didn’t know that.

Make sure to tell him when you see him next.

I have been called various things, but never, “a unit of inductance.”


Haikus

Where to put this page?
NYU servers are slow.
I’ll use my own site.
Which domain to use?
Matchstick? Skeptictank?
Not all are worthy.
From Radio Shack:
Text, “Basic Electronics”
Tandy wins again.
I checked the parts list.
Regulators are missing.
Capacitors, too
Zaftig? What is that?
No links? Text in Japanese?
Mistake? Or true art?
Feddersen seems cool.
(Not like some I could mention)
– No, that’s just a joke.

Here is my new 5-minute site.

Is it not beautiful?

Do you not feel ugly just to be near it?


Matt Slaybaugh

ms171 at nyu.edu

Categories
Making Projects

Blogma Week7

Blogma

Intro to Physical Computing
Fall, 2003
Jeff Feddersen

Week 7


Common Ground!


My home phone number is, apparently, one digit different from the front desk of Screw magazine.

I get some bizzare wrong numbers.


I was temporarily without my bread board, so I did some soldering and hooked up the servo directly to a 5V DC power supply, with red to + and black to -.

The yellow control/signal end was free, and I noticed that every time it came into contact with my skin, the motor rotated counter-clockwise.
Touching the control wire to power or ground had no effect.


Another general electronics-y site: play-hookey.com with guides on how DC power works, etc.

And here’s one all about building analog music synthesizer components.

This one’s even better.

And this one has great, thorough explanations and tutorials of things such as ‘Darlington Pair Speed Control‘: Electronics in Meccano.

And here’s another good site in the same vein.


Tested servo with sample script online – works just as promised.

It makes a funny sound.

I love the little guy.


In college I took a midi class with David Borden, who had worked with Bob Moog (pronounced ‘mohg’) in Trumansburg, NY, just a few miles north of my home town.
He would tell stories about Wendy Carlos (back when she was Walter Carlos).
Borden was kind of a jerk, and his music wasn’t even very interesting.
When he couldn’t think of a melody, he would just take some random piece of sheet music (say, “Jingle Bells”), turn it upside-down, and play it that way, at Carnegie freaking Hall, no less.
I suppose that is an avant-garde technique of sorts, but it sounded terrible.
Still, the class was a lot of fun.


I try the second online script, but the servo just cycles between ‘start’ and ‘minimum’.
I add call putPin(26,0) and see the on-board led switch on and off with each cycle, which tells me the chip is shutting off every time the servo turns on.
It must be drawing too much power away from the chip.
This happened before. I forgot that I need a separate power supply.


I resoldered the connections on my power supply jack, which were kind of threadbare.
Making them nice and solid again seems to have improved my serial connectivity.


The popcorn song was a hit with everyone this week.
I realized that I’d heard that songs lots of times, but never really thought about where it was from.
In my mind, I always associated it with the Axel-F theme from ‘Beverly Hills Cop’.

Paraphrased from an interview with Kingsley:

The Popcorn song was composed by Gershon Kingsley in 1969, who, in addition to surviving the holocaust at age 15 and serving with the British military in Palestine, joined Moogby, the first Moog synthesizer quartet.
‘Popcorn’ was composed “in about two minutes” for the group, and has since become kind of an anthem for electronics musicians.
Kingsley said he uses Macs, and said he prefers Performer and Overture software.

Maybe I should switch back to macs.

The vanBasco’s Karaoke Player is the best midi player I’ve seen.
It’s free, and good for when you don’t have access to your midi keyboard.


I remove the wires connecting the right and left power bays, like Jeff showed in class, and put a 9V battery on the right side.
So now the chip doesn’t shut off, and the servo acts like it’s having a seizure.
The instructions say the minimum pulsewidth of 0.001 and maximum of 0.002, but the code uses 0.0003 and 0.0022.
Hmm.
I change the values to 0.001 and 0.002, but it doesn’t seem to make any difference, although the seizure looks slightly more erratic.


There’s a mnemonic device for resistor colors:

BadBoozeRotsOurYoungGutsButVodkaGoesWell
blackbrownredorangeyellowgreenbluepurple (violet)graywhite
0123456789

(if engineers had invented the English language, we wouldn’t have three basic color names that begin with the letter ‘B’)

So some common resistors in the cabinet are:

  • red-red-brown (221) which = 22×101 or 220 ohms
  • red-red-red (222) which = 22×102 or 2200 (2.2K) ohms
  • red-red-orange (223) which = 22×103 or 22000 (22K) ohms

Now, if I manage to memorize these, would that make me a nerd? Practical knowledge like that somehow seems cooler than your typical nerd behavior.


So now I try 0.0001 and 0.003, but that doesn’t seem to matter either.
I change the sleep from 2.0 to 5.0 – no significant difference.
Change the ‘refreshperiod’ to 0.05, and the only difference is intermittent pauses.
And the servo is getting kind of warm.


How to read a capacitor (it sort of makes sense)
This one takes a stab, too, and one more

Basically, it works like the resistors: the first two of three digits are the number, the third digit is the multiplier, and the letter that follows is the tolerance.
Additional letter codes refer to operating temperature range, which, who knows, we may have some opportunities to test.

Lentils (Ceramic Disc)
18J | NPO (tan)= 18 x 100= 18pF= 0.018nF= 0.000018µF
56J | CO (brown)= 56 x 100= 56pF= 0.056µF= 0.000056µF
681J | KCK (orange)= 68 x 101= 680pF= 0.56µF= 0.00068µF
x | 473.k (green)= 47 x 103= 47000pF= 47nF= 0.047µF
473Z | Z5V (tan)= 47 x 103= 47000pF= 47nF= 0.047µF
10% 3KV | D 180 | N 1500 (yellow)I have no idea. It’s much larger than all the others, but neither 1500 pF or 1500 nF seem right.
Maybe 180nF? (0.18µF?)
Cylinders (info written right on side)
10µF0.000010F0.010mF10,000nF10,000,000pF
100µF0.0001F0.1mF100,000nF100,000,000pF
220µF0.00022F0.22mF220,000nF220,000,000pF
2200µF0.0022F2.2mF2,200,000nF2,200,000,000pF

I put back the original script – no difference.
I notice that if I manually twist the motor all the way clockwise, the first thing that happens when I run the script is that the motor turns all the way back ccw, then vibrates.
Good thing I bought two servos.
I try the 2nd one, and it jitters as well, but in a different way.
Try all the things I did with the 1st one, and they both act the same – even the part about spinning ccw before jittering.
Maybe the example code is bad. The first script worked fine.
Oh, but I try the first script again and it doesn’t work.
Oh, that was before I put in the 9V – that must have too much power – ah yes, the servo doesn’t want more than 6.


I have one little blue thing, that looks like this:



(I used a flatbed scanner to get this image, pretty good – better than my camera)

I don’t know what the symbol on the left is, and Googling for “480BK” didn’t yield much fruit.

I think it might be a timer.



This diagram from Kyocera may be a clue, but I don’t know what that symbol is above the KBR-480K.


So I need a different power supply, or a voltage regulator.
Here’s one, no wait, that’s not a 7805, that’s a NL|CE LM|317T|NLAS947 – an adjustable voltage regulator.
Where the hell did that come from?



Instead of the pins relating to in, ground, and out, this one uses in, out, and adjustment.
So I put it in the board, and… without an adjustment, the output is around 19V so apparently this thing wants 28V in, and can deliver anything from 1.2 to 37V out. So I’ve got it right in the middle now.


This Word doc has a thorough listing of circuit symbols, and leads me to believe that the blue component is a ‘piezo transducer’, although it doesn’t look like the photos of piezo transducers I see on the Web.
But it looks like it makes sound.


To regulate the new VR, I need a 240Ω resistor and a 5KΩ variable one.
I’ve got a 220 (red, red, brown) resistor, close enough, and a 10K pot.
Let’s see how it goes…


I’ve learned that, just as the US has different spelling (color vs. colour), sports (football vs. football), and measurements (imperial vs. metric) when compared with the rest of the world – the US also uses different circuit diagram notation.
The differences are more for logic gates than for component symbols, but geez, why do we always have to be different?
All the same, ours are easier to read.


Now, with the pot turned all the way one way, I get about 14V, and turned all the other way gives me 0V, success!
I guess the difference in resistances in my components is why the max isn’t 37, but I’m not going to do the calculations now.
So I turn the pot and watch with the multimeter until I have about 5V.
Now, to try the servo script again… and… nothing.


Here is a diagram for a Variable Frequency Quadrature Sinewave Oscillator.
I want to try it. I think I might print out the diagram, paste it to some cardboard, and then just lay out all the components on top of the diagram and solder them together.
It requires:

  • 1 100K pot
  • 1 10K pot
  • 2 330pF capacitors
  • 6 1K resistors
  • 4 15K resistors
  • 3 22K resistors
  • 2 100K resistors
  • 4 1N4148 transistors
  • 3 TL072 transistors
  • 2 1/2 LM13700 transistors
  • 1 1N4735A transistor

It uses some odd symbols, such as a simple rectangle to represent a potentiometer, and has triangles here and there with no evident purpose.
Also, some of the connections between components have numbers next to them. I can’t tell what they’re for.


I was testing voltage at the wrong points, across the pot, instead of where the motor will get it.
The instructions also suggest some optional capacitors. Let’s try those as well.
It asks for 0.1µn;F and 1.0µn;F, I have 0.047 and 10. Oh, but one is directional and the other isn’t(?).
I try a few configurations, but no dice.


This British electronics componments site: Maplin seems to have everything. Too bad the shipping charge is so high to the US.
They even have loads of fireworks. Japan sells loads of fireworks, for like, $5/pound. I tried smuggling $20 worth from my last trip, but ever since 9/11, the airport personnel are a little twitchy about piles of explosives being brought aboard. Oh well.


Let’s make it simple, just stick the pot between the battery and the regulator.
Well, I now have a min of 2V and a max of 3 – that’s no good.
Okay, start over. Putting batteries in series should have an additive effect on the voltage, right?
So put two AAs at 1.5V each and, yes: 3V.
So I just need one or two more.


This site has a diagram to make something that is essentially the same as a 7805 (but better input voltage range) for $0.46 in parts.
Too bad the shipping would be more than the cost of just anew 7805.

I’m getting into the whole idea of actually understanding all this stuff. I still have trouble reading a circuit, whether as a diagram or as implemented, but I’m getting better.

Nikolai Tesla was awesome. This page has some good circuit diagrams and projects on it.
I think I’ll try the tesla coil and plasma globe. That would be fun for Halloween.


Shortly before Bloomberg ran for the mayor’s office, his people were hanging out on NYU’s campus, handing out little radios that could only be tuned to one station, the AM broadcast of Bloomberg radio.
I still have mine, ripped apart, but alas, it only has a battery bay with room for two.
No problem, there’s one with room for four in the bottom of junk box #4.
Multimeter says: 6V – finally!


An automated plant-watering system


But dammit, still jittering! I try with three batteries (4.5V) – same, 2 batteries – same.
I try the first script with the same 5V power that’s running the chip – and it’s fine.


Phaedra was talking about bioinformatics.

But what I want is some kind of helmet, full of low-frequency sensors, that detect delta (0-4Hz), theta (4-8Hz), alpha (8-12Hz), low-beta (smr: 12-15Hz), (midrange) beta (15-18Hz), and (high) beta to gamma (18-40) waves.
(Looks like Advanced Brain Monitoring, Inc. is ahead of the game. They have a device called the ‘Cerebrum Profiler’)
You could calibrate it for thinking about left, right, up, down, and ‘enter’, then configure it to play Super Breakout.
That would be cool. I just need to figure out how to do low-emf frequency detection.
This site has a useful diagram.
Man, that would be awesome.

And this site seems to be the mother lode of circuit diagrams.
(Where would we be without Google?)

Another EEG circuit. Looks like we’ll need a 10,000x amplification of the signal.


I now have the 4 AAs powering the servo, which is still jittering.
Futzing with the numbers helps somewhat. The fact that both motors have a left-bias, concerns me.
This guy did a thorough test of pulsewidths for the CS-60.


I need to eat more Chinese food, just so I can get more of those clear plastic tubs. I’ve got resistors in one, LEDs in another…


Oh man, I fucking got it.
I remember overhearing someone say in the lab something about ‘common ground’ so I link the ground between the batteries and the 7805, and voila.
So now I can see that a 0.001 sec pw only gives me 45°, and 0.002 only gives me about 135.
Tom’s numbers are much closer to the right ones, though still a little off on mine.


When I left the lab yesterday, I tossed my random wires, leds, and stuff into a paper bag that was on the floor.
When I got home and was rummaging through it, I found some napkins, which seemed very odd.
Then I found a large slice of chocolate cake in saran wrap.
So, to whoever lost a piece of cake in the lab: it was very tasty.


About two years ago I built a perpetual motion machine, of sorts. It would only make about two revolutions before it was overcome by the friction on the axles. With some better lubricant and more precise gears, I might be able to get it to work. People say perpetual motion is impossible, but if you notice, the Earth has been moving around the Sun for quite a long time. The trick is to have a balance of non-collinear forces. The Earth is always falling toward the Sun, while at the same time hurtling away along a tangent of its orbital path. These forces are at right angles of each other, so the method here on the ground is to use magnets at right angles to gravity.
Several magnets repel each other while fixed to two interlocked gears, both of which are on ratcheted axles, so they can only turn in one direction (1 cw, the other ccw).
It’s not ‘free’ energy, which is impossible, because over time, the magnets gradually lose their field.
It’s very similar to a water wheel – the potential energy in a magnet is converted to kinetic energy.


Looking at that LM317T VR, I see that I may have had pins 1 and 3 reversed. Oh well.


I don’t think I’ll do anything interesting this week for IPC. But I have a plan for how to use the servo for my Halloween project.


I got a sort of robot arm powered by servo working, based on a sketch at http://zzz.com.ru/


Tried building a tesla coil, but I didn’t have any of the right parts. I substituted in a regular transformer for the flyback one, 220Ω resistors for the 240 and 27, and I don’t even know what transistor I used.
I powered it up, and the transformer was working because the steel loop became magnetized, but I didn’t get any sparks.
Then smoke started coming out of it, so I pulled the plug.
The lesson is that electronics is not like making a stew, you can’t just substitute ingredients if you run out.
(I guess I knew this already, but I was hopeful that I might get at least something interesting)

Categories
Animation Kids

Cartoons for Kids

Video
Paul and Mark try to pick a video to watch

Wallet
Mark searches for his lost wallet

Underwear
Paul and Robert talk about clothes

R2C4
Mark meets a new robot friend

Heart of Gold
Man’s best friend

Interactive Storytelling for Children
Diane the Mouse – unfinished

One Week Later

I still get whiffs of ozone every now and then through the window. People speak of feeling numb, but the most numbing thing is to hear people on TV speak so mournfully, then break to commercials for shampoo and contact lens cleaner.

Things are really not so different than they were 2 weeks ago. There are fewer cars on the downtown streets, and village bars that normally sell beer for $5 per glass have $1 and $2 drafts and $0.15 chicken wings because fewer people have been going out. But people don’t instinctively look up now when they hear airplanes overhead.

The incident (which doesn’t have a real name; it wasn’t a ‘bombing’, but more than just some ‘plane crashes’, and ‘attack’ doesn’t completely describe the event) is still the main topic of conversation – what to rebuild on the site, what the consequences of military action will be. However, I now hear people arguing over trivial things. In the first few days, I spent nearly every waking minute with the circumstances in my awareness somehow – but now I only think about it about a third of the time.
People have more distance now, and now status is based on how close one has been able to get to “ground zero”. My boss’ son attended Stuyvesant High School which is just across the street from the WTC, but the school will be closed for the next few months. They went to the school one day to clean out the locker, and he got to be within a couple blocks. So of course we all stood around in a circle grasping for every word. I for one, am eager to hear anything other than the televised melodrama of flag-waving and weepers.

On one news show was a reporter looking at some rubble saying “A simple rag doll. All that remains. Of the people who once worked. And lived. Here.” I couldn’t stand it.

The truth is that most New Yorkers, let alone Americans, were never in any danger during the entire event, and most were not even inconvenienced. 10 times more people die each year from drunk driving, yet terrorism is treated like a bigger threat. I guess because it’s preferable to kill thousands of foreigners than to try to change behavior. It’s preferable to invade than to just pull troops out of Saudi Arabia and apologize for damaging the image of Mecca and Medina. America has been a bully for a long time, and I think everyone who has ever been bullied sympathizes to some degree with the Afghans, while those who have been bullies are the ones arguing for war.

The Columbine shootings, and similar episodes which now seem part of an epidemic, are more of a threat to American school kids than terrorism is, yet in response to which nothing was done or is done. But those shootings were motivated by the same feelings as last Tuesday’s attack: a small group resented being marginalized by an arrogant, affluent, aggressive group – and couldn’t take it any more. The name of the U.S. military retaliation, “Operation Infinite Justice”, shows that America is still incredibly arrogant, not realizing that the plan, “To rid the world of evil” is the objective of both sides of the conflict.

I feel like a curmudgeon when I see all the patriotic images, but I think all the fear and sadness is self-indulgent: focusing on one’s own emotions rather than the real issues. I find myself humming tunes such as “God bless America”. But that’s because I hear them all the time these days.

$5 is the universal price for souvenirs now. In addition to so much else, I also don’t like the crassness downtown; postcards that have the image of the towers go for $5, and tourists take pictures of everything, even of the funeral processions around town. I guess they want every image they can get of every attack-themed scene. Last week, some theaters had free movies, since no one was going and they were losing money, but the popcorn was still $5 for a large. Last Wednesday, the Times ran out of issues quickly. A few entrepreneurs bought thousands of copies, in order to sell them as souvenirs. Most people aren’t sad or afraid, they just see an opportunity to make a few dollars.

A lot of rats were displaced by the building collapses, and have moved north. Some of these are 5 or 6 pounds, and I’ve seen many more than usual downtown, both live and dead. They may have been attracted to the stench of fruit and fish stores and groceries that hurriedly abandoned stores a week ago, and left perishables locked up unrefrigerated for several days.

It is a little freaky working at the UN. They still have lots of extra security, and still have salt-spreaders full of sand blocking off the streets around the Secretariat. The easiest job is that of the dudes sitting in the trucks, backing up to let occasional police cars through. I learned that there was a plan in 1993 to bomb both the WTC and the UN, but the UN attack was thwarted. There was a suspected attack at the UN last Wednesday, and the terribly inadequate evacuation measures scared many people more than the actual threat of an attack. Fortunately I work across the street from the Secretariat.

I remember sitting next to a cricket player a few weeks ago on the plane from London to Bahrain in the UAE. We discussed my job at the UN, and it was clear that he felt that the UN was just a tool of the US, and that Arab countries could not trust the actions of either organization. It was interesting to visit the airports in Nepal, the UAE, England, and the US during my trip. JFK airport was the only one that had totally incompetent people working in every capacity, who didn’t even try to look at my bag, who let the restrooms fester, and got angry with me whenever I had a question. The airport in Abu Dhabi had the most courteous and helpful staff, as well as the most armed guards – but also most obnoxious kids running circles around their oblivious parents.

A Perverted Carnival

I went to a perverted carnival today, walked down 6th Avenue to gawk with the rest. From 2 blocks from my street to as far south as I could see was a single column of parked Komatsu backhoes. An orange and white cat was trying to climb the front right tire of one, but it was too high for it to get a foothold.

At any moment along Canal Street now are more spectators than died during the entire ordeal: people wearing American flag hats and t-shirts, eating $3.50 hot dogs, taking snapshots, and griping about the poor view. A few middle eastern men were doing brisk business selling overpriced refreshments, and I overheard one guy comment, “You burn down our buildings and you want our money too?”.

Many of the people looked like the type of people seldom seen in Manhattan, a family where every member is so fat that they have to lean backward when they walk in order to stay upright. The kids carry balloons, and play game-boys while their parents crane their necks to see beyond the bored and tired-looking policemen and women. I hated these people for their ogling, but realized I was there for the same reason.
There is still a lot of smoke, but yesterday’s rain cleared out the lingering dust. I still can’t actually believe what happened, and it’s very strange to see a southern horizon without the twin towers.

I struggled to head toward Pier 40, which is a relatively quiet place where I sometimes go to get away from the noise of the middle of the city, but it was also full of spectators. Walking north I passed a few fire stations, one around the corner from my building. Each had hundreds of flowers and ribbons, and the gatherers seemed more respectful of the situation. I heard that 4% of all fire fighters who have ever died in the line of duty in the history of New York City died this past week. I felt some shame that I make a living sitting in front of a computer.

The most solemn vigil is at Union Square, where there is nothing to stare at. More people there have lost a friend or relative, and the hundreds of pictures taped to the walls are quite touching. Now that traffic is allowed below 14th street, however, the singing and prayers are disturbed by car horns and the rumblings of garbage trucks.

There was true unity here on Tuesday and Wednesday, but that has faded each day. Now we hear of lootings near the site, or of kids pulling out knives on a public bus and pretending to hijack it, threatening to drive it into the Empire State Building. At work also, on the first day back we all commiserated and shared stories, but on Friday we argued about what we should do, as part of the UN. The art director had grown up an air force brat and was unwavering in his ideas of encouraging American patriotic images. The editor felt that we still all needed to heal and reflect before doing anything. I was the only one who was critical of the rabble-rousing and encouraged greater education about the backgrounds of the suspected terrorists.

I’ve become a news junkie, listening to hour after hour of updates, then getting so sick that I can’t stand another second, only to turn it on again after a few hours. Fox news seems to have the most irresponsible journalism, fanning the flames of anxiety that then lead to anti-Arab feelings and the search for quick solutions. But I listen anyway.

We have mail and garbage service now, and the local bodegas and laundromats are open now. It’s convenient to have services back, but I actually liked the temporary peace. As old routines are fallen into again, the usual brusqueness of New Yorkers is back. As we go back to work, it’s hard to sustain the initial outrage and desire for action, and I’m afraid that the only people that are able to are the jingoists whose zealotry matches that of the hijackers.