This small transmitter appeared in the March 1989 issue of Radio Electronics magazine. The two-transistor circuit used an electret microphone and had a range of a few dozen meters.
This is another practical idea found in a 1997 documentation. This circuit allows a DJ to change the...
This circuit can be used as a shield for touch control. The circuit can use any common FET like...
This circuit was obtained from a 1970s RCA. The circuit uses LDRs as sensors. The resistors depend on the...