It works great on CoCo3's... I have yet to test it on my CoCo1. Will update this spot when done.
Special thanks to Richard Lorbieski, who gave me his permission to share this article, which originally appeared in The Rainbow, May '91 (correction appeared in August). Thanks also to Robert Sherwood for the excellent scans (with corrections no less!), Bruce Calkins for pointing me to the article in the first place and of course to The Rainbow, without which all of our CoCo's would surely have been less fun!
So what are you waiting for? It's a very easy circuit to build
and cheap! I spent about $2.00 at the local electronics store, including a
small perf-board. Here's how I laid it out: