This is a Japanese commercial radio from the 60s. The superheterodyne circuit of 7 transistors for medium waves has 200mW of output when powered by 4 common batteries.
This 1/2 hertz high selectivity filter was found in the December 1990 issue of Radio Electronics...
The frequency in this circuit is adjusted by P1 and given by C1. Short pulses, as the ones...
This Hartley telegraphy oscillator operates with the transmitter signal generating a tone in a...