Found in a 1967 Electronics World, this oscillator changes its tone when objects move in their environment. The output is made on a low impedance phone.
This TTL circuit was found in the December 1990 issue of Radio Electronics magazine. The circuit has...
Found in an Electronics World of 1968 this circuit can use any SCR and diodes depending on the...
Placed near a telegraphic transmitter (CW) and with a small antenna or pickup, it reproduces the...