With the configuration shown in the figure, we have the relay being activated when the microphone picks up a sound and shutdown when the X1 reset sensor is activated.
This circuit was found in a 90's RF Design. The circuit employs an integrated of the time. The 56 to...
Found in a 1990 Hobbyst Handbook this circuit has an output power of a few tens of watts and...
This circuit was found in a Popular Electronics of 1993. The operational amplifiers can be the...