This circuit was found in a 80's Popular Electronics. The sensor can be any phototransistor. The circuit is indicated for an audio link modulated in pulses.
This 1956 direct amplification radio circuit was found in a documentation from Sylvania that...
This conventional oscillator with the 741 can be precisely adjusted to produce a 400 Hz signal. The...
This circuit uses two diodes in a doubling configuration to receive medium-wave range signals. The...