I had some success today with breadboarding a DTMF based 16 channel audio sequencer. Thanks to John Schuch for the original idea and for drawing up the schematic. The basic idea is to be able to route an audio signal to any 1 of 16 speakers. You control it by feeding it stereo audio - in the left channel, you have the DTMF tone corresponding with the number of the speaker you want the sound to come out of, and in the right channel, you simply have the sound itself.
At this stage, I am using 8 LEDs, instead of 16 relays, LEDs because the relays I have don't line up nicely with the breadboard, and only 8 because I am lazy. You can see them blinking away in an entirely unexciting fashion in the video below. While not being very exciting, those LEDs lighting up certainly gave me a sense of accomplishment.
I ended up bending 2 of the things I got yesterday for the Circuit Bending Challenge. The driving toy was very straightforward, it had your standard black blob IC inside. I replaced the volume and pitch resistors with pots and added a switch for the 'indicators' sound, since it makes a decent beat. It doesn't sound as good using the 6.5mm output jack, I might need to do something to emulate the speaker better or try a transformer.
The 'black mystery box' was pretty cool to start off with so it didn't need much to take it to the next level. I gave it an RCA out and a switch that puts it into constant burble mode. There were some good pitch up and pitch down points but without re-casing I couldn't use them unless I went for touch contacts and I didn't have anything handy. They way it goes off at random intervals makes it great for doing some dub style bleeps, as I demonstrate below.
I uploaded some .wav files too, but I have to wait for them to make it through the moderation queue before I can link to them.
UPDATE: I finally remembered to post the link to the WAV files.
Circuit Bending Challenge Sample Pack @ The Freesound Project
Sweet! They've scored a bunch of MacBooks to use for the Process Space. They have these funky transparent shells with a big colour printout inside, telling us that the laptops are sponsored by www.mac1.com.au .
Digging out the breadboard has been good, because it seems to have coincided with a lot of cool CMOS based audio projects appearing online. The coolest I have found so far has been fun with sea moss by Sebastian Tomczak. I made up a little shopping list and went and got the bits and pieces I would need to start building some of these 4000 series CMOS based circuits. It's actually fairly fun putting these together, I put together the one in the video below while watching TV. It's sort of like playing with Lego, all the bits just click in to the breadboard sockets.
The 4066 quad-switch in particular is pretty useful - GetLofi has a few interesting posts featuring this chip.
Some other interesting circuits I found via YouTube:
Binary Pattern Sequencer
This one is particularly nifty as it is going to be used in an Electrofringe workshop this year. I'm definitely going to sign up for that one!
Vactrol Pattern Sequencer
Atari Punk Console controlled by 8-step Sequencer
Another nice idea to look into is using an Arduino > LDR setup via PWM LEDs to create a cheap version of the Highly Liquid MIDI potentiometer board. With the right code you can control up to 12 LEDs from an Arduino. So, without figuring out some kind of multiplexing, a 16-step sequencer is out, for now. There are other potential options here though - simultaneous pitch control for 12 circuit-bent toys! Good god, that's more polyphony than most benders will ever need. Think of the racket. The latency of the LDRs should have a nice smoothing effect on the PWM LED output too. Futurlec have some nice and cheap digital pots, which I am planning to order and have a play around with. I'm liking the "Arduino Vactrol" idea right now because it is pretty useful if you happen to have a couple of circuit bent devices with LDRs around, like I do. I actually found a demo of this exact idea on YouTube last night Arduino controls a resistor.
OK, that's enough rambling for today, here's a video of the first "fun with sea moss" circuit I have built so far. I threw a bit of delay on it inside iMovie to make the squeals and groans a bit more palatable.
I just bread-boarded a basic 5V power supply section. Pretty basic stuff, but it's an important step as I have only used breadboads as scratchpads, rather than building complete circuits. I was inspired by this tutorial by Spark Fun, which was linked on MAKE: Blog recently. I happened to have a LM805 floating around, so I went for it. It has a 220uF cap instead of 100uF and I left off the 10uF cap, since I didn't have one handy. Should be OK, since I'm using a 12V laptop switchmode power supply that was being thrown out at work.
I also played with the Arduino tonight and hooked it up to an LDR and a piezo transducer to try out the theremin sketch from Todbot's Spooky Projects for Arduino.
It sounds less like a theremin and more like those random burbly tones that they used to use to represent computers in old movies. Which is fun.
Bugger, just noticed that the pic is mirrored, since I took it with Photo Booth.
Aha! I just went and looked at Photo Booth and found an option called "Auto flip new photos" which I have now turned on.
Just testing the Vox video upload feature with something I made a couple of years ago.
The original file is 73MB, MPEG2 encoding. Not sure if it gets transmogrified by the server.
Recent Comments
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Evil Paul said:
It really is a mystery, I have no idea. Someone suggested it might have been part of a Halloween costume. read more
on Circuit Bending Challenge completed! [UPDATED 21Mar08] -
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Keith Handy said:
So what exactly is the mystery box in the first place? read more
on Circuit Bending Challenge completed! [UPDATED 21Mar08] -
Evil Paul said:
Turns out that it gets flash-ified, which is obviously less fun than being able to host mpegs and avis. Seems... read more
on We cannot escape this miserable world
on Mystery Box