This low frequency sinusoidal oscillator was obtained in documentation from the 1970s. Operational equivalents can be used. The FET is a general-purpose type.
We found this multiple thermostat circuit in July 1980 Radio Electronics magazine. It uses...
Other operational amplifiers can be used on this unit gain amplifier. The circuit is from the 1993...
This interesting circuit with an indicator tube powered by a transistor inverter was found in...