Suggested by Motorola documentation from the 1980s, this circuit can be implemented with equivalent power MOSFETs. The type depends on the current of the controlled motor, as well as the diodes.
With the configuration shown in the figure, we have the relay being activated when the microphone picks...
This TTL generator that can function as a control shield or external clock for microcontrollers was found in...
The OP07 operational amplifier is not common today, as the circuit is from an old European manual....