This approach alarm circuit was found in the September 1970 Radio Electronics issue. The 1 mH coil is wound on a ferrite rod. The relay is 12 V sensitive.
What differentiates this circuit from the previous one is the need for a much smaller current to...
This circuit can operate with 5 uV to 1 mV input signals from low impedance sources such as...
This circuit of an English publication from 1993 indicates when the active cycle of the signal under...