This variable frequency oscillator with the 4093 was found in a Popular Electronics from the 90s. The table gives the component values for various frequency ranges.
We found this multiple thermostat circuit in July 1980 Radio Electronics magazine. It uses...
This circuit is from a 1986 Revista Española de Electrónica. It consists of an amplifier with...
Suggested by a 1968 Philips documentation this Eccles Jordan rocker as it was called can operate...