This circuit turns off when switch S1 is opened. The circuit is from the 1989 Radio Electronics Experimenter edition; The triac must be controlled according to the load.
This circuit is a driver for R-2R network of AD converters. We found it in manufacturer...
This circuit was found in an American publication from the 60's. The transistor is made of...
This circuit produces an audio tone on the speaker or magnetic capsule. Rx must be such that added...