This circuit is from the LM107 manual. This operational is from the 80s, but the configuration is valid for any operational. The formulas give the gain of the circuit.
This touch switch uses components that have easy-to-obtain current equivalents. The power supply...
After starting, this circuit turns off the relay in a time that depends on the 4020 pulse-count. This...
Connected to the output of a small amplifier or receiver, this circuit triggers a relay in the...