This circuit, from the 70's, can be assembled with a more modern FET like the BF245. The circuit is powered by a 9 V battery, as its consumption is very low.
This is the receiver circuit for the previous remote control published in the same Radio...
This circuit, for signals up to 1 MHz, is based on an RCA operational amplifier. The circuit was...
This frequency shift modulation circuit was found in the November 1994 issue of Electronics Now...