We found this receiver circuit for modulated light in a 90s Popular Electronics. Equivalent audio amplifiers can be used. Transistors are commonly used.
082E) We started with a simple Hartley oscillator circuit using a bipolar transistor that can...
Developed by Philips this 60's circuit uses a transistor of the time, but the configuration holds true for...
This circuit takes advantage of the LC constant of a capacitor and the coil of a relay to...