Generate AM Radio Broadcasts With Your Monitor

tessellation writes: "Tempest for Eliza is a program that uses your computer monitor to send out AM radio signals. You can then hear computer generated music in your radio." Here is your big chance to disrupt free thinking radio programs in your neighborhood.

Comments

Done it...

[Kymermosst]

It really worked... it took more work than the instructions portrayed to get it working, but it's pretty nifty.

Can't do MP3s yet... at least, not the version I tried.

first post?

Back in ancient times

[ynotds]

This is really testing my memory, but I think it was after we upgraded from our IBM 1440 to an early System/360 that our operators discovered they could tune an AM radio to a certain frequency and thereby listen to the puter.

Maybe somebody with a better memory might know a few more details.

Re:Back in ancient times

[Florian Weimer]

Our local computer museum has got a PDP-8 which can broadcast polyphonic music using its main CPU, running a specially crafted sequences of instructions. Actually, operators used the AM radio effect to monitor the machine activity. With some experience, you can here if the CPU is idle or spinning in some kind of endless loop. If you are familiar with a longer job, you can guess which part is currently running, and estimate the remaining time.

At home, my computer has a similar feature: if the CPU is loaded, the sound of the fans changes, so I can tell if the computing-intense job is still running or not.

this reminds me...

[anotherone]

This reminds me of a game I used to have for my TI-82. As I recall it was a dumb game, but it was the first (and as far as I know, the only) calculator game with music.

I think it worked by twiggling the link port's connection really fast or something, but if you held it near an untuned radio, it'd play really poor music. Really, really bad music. But, hey; what do you expect from a damn calculator?

Anyway, this is one of those completly useless, yet incredibly cool things that I like to see. Very neat.

Re:this reminds me...

[FuegoFuerte]

Actually, quite a few of the games for the TI-86 have music. Mario does, and I believe Tetris does also. (at least the versions I had). I've since gone to the TI-92+, and haven't tried it with that. On the 86, I heard rumors that you could tune it with an AM radio, but you could also plug headphones straight into the data port (with an adapter to go from the 2mm to the 3mm plug) and hear the sound great. Someone actually wrote a program to play music that way, though you can't fit much music into the memory on the 86. Pretty crappy quality too. You can probably still find the programs and info on ticalc.org or somewhere. It's been a couple years, so I don't remember where I first found out about it.

Weird.

[MasterOfDisaster]

This could be one of the stranger uses of standard hardware I've ever seen. Would it be possible to make signals more fun then just beeps? Cause, beeps are cool...but, brodcasting audio at a higher quality would be very cool. I mean, hell, we all have some spare CRTs laying around...it could be your own personal radio station! no need for a stinkin transmitter...you can just use your screen.
I shudder at what people will come up with next...

legality?

[rootofevil]

Doesnt every piece of electronic equiptment i own have that little FCC sticker that says it must accept any undesired interference, but not cause any of its own? wouldnt this fall under that exact category?

Re:legality?

[ocelotbob]

This is perfectly legal. All electronic equipment is spec'ed to a certain amount of interference it can radiate. What this hack is working on is the fact that a monitor should be sending out a pretty fixed frequency that can be picked up by an AM radio, similar to how you can hear a repetitive beeping sound if you hold a remote next to an AM receiver in just the right spot. The FCC doesn't care because unless you do some heavy tweaking to your monitor, this isn't going to affect more than the 10-15 foot radius a monitor would normally slightly affect. You're allowed to microbroadcast that amount of distance.

FWIW

[adolf]

While the instructions say to use a shortwave radio tuned to 10MHz, I found that a regular broadcast-band AM radio worked fine. Just chop a zero off of the frequency, and tune in somewhere around 1000. (1030 was what my tuner said, at the point where the "music" was most plainly heard).

Spooky stuff, this.

Wireless LAN

[cra]

So, basically, by hooking up some old AM radios ("slightly" modified, of course) to every computer in my home, and by installing some sofisticated software (Will I need a "slightly" upgraded version of the mentioned software, I wonder?), I can actually have a wireless LAN in my home, right?

Can this be used for transmitting voice?

[dhanav]

Code a picture that will produce a voice and we have an encrypted speech. Sounds interesting. I am going to display all those pics in my collection and listen for hidden messages :).

Geek history

[pacc]

It all began somewhere in California when a student didn't think that pulling a few switches to get a few red lamps to produce the answer was good enough.

With a bit of experimentation he produced a program that did nothing, but when he tuned in the radio next to the old monster a small tune was heard when his program was run.

Other Examples: One of the highlights of our open day display was a music program running on the DS300. This machine has no loudspeaker - the four-part harmonies are picked up by an AM radio tuned to the rf interference generated by the core driver circuits. For best results, pull your PDP-8 processor cabinet right out and place the radio immediately above the core stack.
Resurrection, some kind of antique computer society

Can't find the correct reference, try yourself to search the net for computer, music etc

Legal issues

[Pat__]

I don't know the range of this thing :)
But correct me if I am wrong ... Isn't it illegal to broadcast on AM frequencies without a licence in most parts of the world?

Re:Legal issues

[Tycho]

Don't tempt me. Also to produce X-rays like that you would somehow have to defeat the X-ray protection circuit. Not impossible just harder to do. Another great thing to concentrate those X-rays would be to unplug or remove the vertical and horizontal deflection coils and fix some of the other components so there is no more vertical or horizintal deflection that occurs in the monitor. The electron beam would then come out as a point on the screen. Which would be great fun as long as you were at least a half mile away when you turned the monitor on.

Done it before on a TRS80 ModI

[Chas2K]

Trash80 hackers did something like this about 1979 - 80. We also had hacked some hardware to the expansion port to read RTTY and CW. In order to prevent RFI we pulled the case apart and lined it with foil then grounded the whole thing to suppress the noise. The trick is not to broadcast a radio signal but to prevent it. A CB neighbor came over because a Made in China PC switching power supply was blocking out his rig through the power lines. I tried everything from ferrite beads to bypass caps on all the lines and never fixed it. Bought a PS made in Taiwan and never had a minutes trouble since. A lot of the electronic parts coming in from China do not have to meet the FCC part 97, class B rules, or whatever the correct ruling is. Another sweet deal cut by the Feds to favor Chinese goods over American or other countries.

Floppy Drive Music

[kotku]

A guy at school years ago used to get his kicks by getting various computer peripherals to play music. The best was a 5 1/4 " floppy drive playing yankee doodle dandy. I think he just drove the head on the drive back and forwards in time with a sound input file. Dot matrix printers could also pump out a pretty tune.

Unfortunately I know longer know this person and a cursory google search turned up nothing on floppy drive music. If anybody has a program to do the same then please post. I don't recommend running this on your own computer though :)

Sweetcode had ya beat!

[TheLocustNMI]

SweetCode had you beat on this one! It's a great little site. Imagine, if you will, Freshmeat with all the chaff removed.

ZX-81

[ThierryD]

Well, back in 1983, I had a Sinclair ZX-81 (also resold in the US by Timex, I believe) with a whopping 1K or RAM.

I purchased a program that did exactly that, but wihth the mother board.

Put a radio next to the ZX and you could hear Jingle Bells. Not great quality, but pretty neat (in those days).

Almost 20 years later, today's computers still can not beat the power of a ZX-81!

Re:This isn't the first

[b1t r0t]

Way back in the real "way back in the day", around 1980 or 1981 or so, before the FCC got into the act, I was using the RFI from my TRS-80 to generate music. The cool part was that any code to generate sound out the cassette port was sufficient to have the sound show up on an AM radio via RFI.

Re:Talking about ancient times...

[GTMcD]

About 1965 Richard Smiley, a student at Carleton College in Minnesota, wrote a program that could play music (sort of) on an IBM 1620. You could listen to it on an AM radio placed near the machine. The 1620 was a variable word length machine, and the word length affected the time it would take to accomplish a task, thus changing the radio signal. Smiley exploited this variation to generate musical tones. IBM included this in the contributed program library that was available to all 1620 users.

Musical smashing disk heads on an Apple II

[hoggoth]

A long time ago I had written a 6502 assembler program on my Apple II that tried to seek track -1 on the floppy drive, then paused a set amount of milliseconds, then did it again.
I got it so I could play songs by the vibration of the drive from the read head banging into the end of it's arm.

This did, however, void my warantee.