Found in a documentation from the 90's, this circuit already includes an amplification stage. The 12 V power supply allows its use in the car.
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...