This circuit was found in the July 1992 Radio Electronics magazine. Sensitivity adjustment is made at R6. Supply voltage is matched to that of the relay.
This circuit split the voltage of a Power supply allowing it to be used as dual supply. The limit...
This modem circuit using a 4046 PLL was found in the October 1994 issue of Electronics Now. The...
This simple circuit presents a voltage gain of about 1,500. The input impedance is high and the...