This optical theremin was found in a 90s Hands-On Electronics. The basic frequency is given by C1 and the output is made in a speaker through a small output transformer.
This LED signaling circuit uses a programmable unijunction transistor (PUT) as a relaxation...
This decoder filter was found in a 1975 documentation. The integrated circuits can be 741. The...
We found this circuit in the January 1997 Electronics Now magazine. The triac determines the...