This circuit works with the previous two by demodulating the signals received modulated in FM. The circuit is from the Radio Electronics magazine of December 1992.
This circuit was suggested by Motorola's 1993 Linear Interface ICs. Equivalent operational amplifiers...
May 2017 - Texas Instruments' new OPAx388 operational amplifiers can now be purchased from Mouser...
This experimental touch switch uses two general-purpose NPN transistor. The lamp can be replaced...