This timer for long time intervals is from the 1990 Motorola Linear Databook. The setting applies to other operational ones and component values are given below the diagram.
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....