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 circuit was obtained from an English magazine from 1976. The circuit operates two LEDs and...
Found in a publication from the 60's, this power supply has no regulation, but only current...
This circuit can use the LM148 and its more modern equivalents, generating a sinusoidal signal whose...