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 circuit was found in Radio Electronics from the 90s. The transistor is for general use. The...
When the temperature rises above the value adjusted by P1 the relay triggers on. The rated voltage for the...
This circuit was found in a 1987 publication. A 4017 sequentially counts time in steps set by...