This is the traditional H bridge configuration for motors. The circuit is for currents up to 500 mA, but with higher power transistors such as the TIP31 motors up to 2 A can be controlled.
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...