Found on a 1964 CQ this circuit is intended for tone frequency change modulation (FSK) telegraphic transmissions. It operates with signals of 2.975 and 2.125 Hz.
This interesting logic circuit was found in a manual of neon lamp applications. | Clique na imagem...
This variation of the previous circuit produces a pulsating sound when the sensor is activated. The...
This circuit allows controlling a LASER pointer with an input logic signal. R has 10 ohm for 3 V...