--== lab rat ==--
bent disney piano toy circuit

lab rat


After I had expressed my interest in circuit bending to Dustin, a small plastic Disney piano showed up on my front porch within a week. He told me that he picked it up very cheap at a second hand store in Seattle. The piano toy didn't sound that great (two tones couldn't even be played at the same time!), but some of the sound effects would interfere with one another and power glitches would make interesting sounds.

The device was opened and probed for possible bend points (see below for notes regarding the probing/discovery process). A set of target bends was decided upon and the necessary parts were purchased.

The new instrument has been named the lab rat. The name is based heavily on the fact that Mickey Mouse was originally printed on the case. The final device sounds much larger than a mouse (RAT), and the surgery was performed entirely in the ilab (LAB). The pure sterility of a laboratory environment is conveyed through the solid white paint job.

I am quite happy with the final creation, although I would have probably done a few things differently if I was modifying this device again. My biggest dissapointment is that I was not able to discover any bends that cause unattended sound/noise generation. As such, the instrument must be constantly manipulated by a human in order for sound to be created. I am also slightly upset because I discovered a wonderful bend that created a rhythmic clicking sequence, but it vanished when everything was completed.




The following sounds were recorded directly from the finished bent device on one take without any effects. All silence has been left intact and the volume has been normalized to 100%. A mono line-out was run from the bent device into the line-in of an on-board (crappy) sound card to create the recordings. Despite the high sampling rate, these are not professional quality recordings. All recordings were created spontaneously and without practice. They are here to provide a short taste of what the lab rat sounds like.


A big warm hearted THANK YOU to my brother Dustin for the toy donation and constant inspiration.

Note: The notes below were "jotted" down while the device was in pieces... they probably aren't very useful...


    pot from pin 6 to +v gives extended notes, noise, then
          eventually gives different infinite note even with power off
          power off with this gives interesting results
    pot from after resistor on pin 2 to pin 6 gives similar to above,
          and can create really long notes/tones
    1uF cap with (-) on resistor on pin 2 to pin 7 changes the tone
          and sounds like it gets more square/electric, although
          not *too* interesting
    pin 8 through cap to +v gives interesting rising tone.  different
          caps here do different things.  a 474nF cap here on a 
          momentary to +v enables a glitchy mode that sounds pretty
          great and can be human contact pitched.
    pin 7 on the + side of electrolytic cap ( 1uF) to ground sounds
          nice, and with human contact can be put into a nice clicking
          rhythmic mode.  A larger cap (100uF) did the same thing
          but went directly into the clicking rhythm mode w/out
          human contacts. A 5nF non-electro cap in the same pos 
          pitched it down a noticable bit.
    5nF cap from pin 8 to gnd gives really nice sound that rises (similar
          to what happens when this pin caps to +v.  This ground cap
          sound is excellent with finger contacts.
    POT PIN 6 TO GROUND...this changes the tone duration and makes it shorter
          use big pot to get back to near default sound.  This gets very
          atari sounding.  This is a must.
    add a nice big cap (oh, say 1000uF) on pin 6 to get long, quiet tones that
          will build in volume when key pressed multiple times.
	      or, if you just want a constant volume, loud tone, tie this
          to +v.
    on the sound effects sub-board, there are some great body contacts 
          (like both sides of the resistor) that can pitch.
    hooking sound effects sub-board output (middle of three pin connector)
          to far side of "input" resistor (essentially shorting it out)
          makes the sound effects board freak out...I'm gussing that
          it's dumping current and resetting, but it makes some cool
    1uF cap from pin 13 on sounds effects IC to ground pitches the
          effects down quite nicely. Similar to both above, putting small
          resistor in parallel with sound effects resistor pitches way up. 

 * Body contacts to pins 7 and 8 on tone gen IC
 * Body contacts to +v and ground (disable when power is off!!!)
 * Body contact to base of output driver transistor
 * Body contacts to pins 13 and 14 on sound effects IC
 * 100uF cap from pin 7 to ground enabled by on/off push button
 * Push button (on/off) to short across driver transistor base resistor
   (this kinda kills piano/tones, but enables cool effects glitches)
 * Pot pin 6 on tone gen IC to ground (10 or 100k?)
 * Power LED
 * 1/4" output jack
 * Power jack and switch to toggle from batt/jack