This circuit was found in the November 1992 issue of Radio Electronics magazine. The circuit has an amplification stage for the relay. The relay is rated at 12 V.
In the figure we have the basic configuration of an operational amplifier for audio signals. The...
This General Electric circuit produces pulses of light only when light stops shining on the...
Found in an Electronic Design of 1964 this circuit has a control for the frequency and another for the...