Sunday, May 27, 2007

Circuit-Bent Speak & Spell

Last week I was finally able to get a reasonably priced 1978 Texas Instruments Speak & Spell from ebay. Shortly thereafter, I was fortunate enough to find the time to tear it up. I wouldn't really say I tore it up because it still works like new; I just modified it to make it better. I pretty much went by the plans for circuit-bending this model laid out by Reed Ghazala in his book on the subject (Circuit-Bending: Build Your Own Alien Instruments). This is also called an incantor and the instructions for building one are laid out in this article by Reed Ghazala except that it uses a Speak & Read.

Here are some before and after pictures of my project:

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Here's how it looks on the inside:

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The main ways my incantor varied from the plan in the book was that I could not get the potentiometer to control the pitch. The circuit he described and every nearby point either did nothing or it locked it up. Hopefully I can work that out soon; I would appreciate some suggestions. Here is a close-up of my board:

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While trying to find a pitch control circuit, I did find a different bend that turned out to be really good. I put a rollerball switch on the inside and ran it through the potentiometer, so that it takes effect only when the machine is turned over or shaken. The pot doesn't really make much noticable difference.

Here is a demo of the performance of this Speak and Spell Incantor. I have more posted and some links on my circuit bending page.

My only advice at this point is to keep in mind that this activity is for small battery powered electronics only. Also if you are planning on buying a soldering tool, a battery powered one may not be the best choice. I used a Weller BP645 and I noticed that I only got a few good hits on it then it wouldn't get hot enough and caused some sloppy soldering. I had to replace the batteries (3 AA), which were still fine for other uses, three times before finally going and buying a regular one with a cord.

Update 6/4/07: I have added some downloadable normal and bent sounds from this speak and spell incantor in both mp3 and wav format.

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