Last Updated June 04, 2007
Texas Instruments Speak and Spell Incantor
I bought this 1978 Texas Instruments Speak & Spell from
eBay. Then I 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's how it looks on the inside:
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:
While trying to find a pitch control circuit, I did find
a different bend that turned out to be really good. I put a roller ball
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 noticeable difference.
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.
For comments please visit the blog post or email me.