Recently I've been playing around with some of the oscillator projects outlined in Nicolas Collins' excellent "Handmade Electronic Music", a must-read for anyone interested in home-grown audio. This finished project is constructed around a single Hex Schmitt Trigger integrated circuit that is wired to oscillate at three different rates, resulting in a nice droning cacophony. Two of the oscillators are controlled by photoresistors, and the third is regulated by a 50k potentiometer. A second 10k potentiometer is wired to the positive line from the battery (creating a variable power starve), and also to the output line of one of the photoresistors - dunno why, but it seems to add that extra little something something.
Here's what the final breadboarded circuit looks like:
Sounds good - now it's just a matter of transferring it from the breadboard to a regular circuit board, and finding a box to house it.
Interior of completed Drone Box. The battery is held in place with velcro.
The two small holes at the center are for the photoresistors, which are held in place by plastic soda straws.
Then I put together a second Hex Schmitt Trigger oscillator, the output of which is connected to a single LED. The LED blinks at a variable rate controlled by two potentiometers.
Next I inserted an LED into one of the photoresistor holes in the Drone Box. The LED was then attached to the second oscillator output with clip leads and held in place with electrical tape.
So, what does it sound like? The first video below shows the Drone Box with the pitch of the photoresistors manipulated by a flashlight. The second video shows the box with the oscillation regulated by the blinking LED.
My plans for a productive 3-day weekend devoted solely to art-making were dashed by some charitable person who donated a Barbie Karaoke tape recorder to the local Goodwill. Not too long ago I read about circuit bending one of these on Peter Edwards fantastic Casper Electronics site, and I've been on the lookout for one ever since. After buying a stack of fresh batteries and looking over the bending schematics I started poking around the main circuit board and identified a bunch of bend points, mostly around the echo circuit. The Barbie Karaoke has a cheap "echo" feature that when bent creates strange and wonderful noise which are generated once you turn the tape player on. After finding about 20 different bend points I decided to build a separate panel on which to mount the the various components, similar to what I did with the Caisotone. The Karaoke machine would be attached to the top of the panel with the wiring running through holes drilled in the bottom, then soldered to the various components inside the panel. Each wire attached to a bend point on the circuit board was soldered to one of twenty banana jacks, which can then be connected by lead wires to a series of potentiometers. I also added a pitch adjustment (located towards the back of the panel, on the left) and both an input and output jack - another cool thing about the Barbie Karaoke is it has two input lines (one for an audio source like a CD player, and the other for a microphone) so you can plug other stuff into it, such as other Barbie Karaokes.
Some photos:
Partially wired panel with banana jacks, switches, and potentiometers. Each pot can be turn on & off with it's own switch.
View of circuit board back in place with bend points all soldered up & wires fed through holes drilled in the bottom of the karaoke. The bundled wires at the top of the photo are all soldered to points on the echo chip.
View of bottom of completed panel. The Barbie Karaoke is attached to the top of the panel with a single screw.
Finished!
Finished view with lead wires plugged into various bend points.
I'm really pleased with how this piece turned out. There are a few other mods you can do, such as adding a variable speed controller for the tape player that involves replacing some circuitry - maybe next time. For now I'm happy to experiment with this as-is:
Interior of completed Drone Box. The battery is held in place with velcro.
The two small holes at the center are for the photoresistors, which are held in place by plastic soda straws.
