The circuit shown is from Texas Instruments optoelectronics documentation. The input signal is audio and equivalent LEDs can be used. Other operational amplifiers can also be used.
With this name, we find a photorelay in a publication from 1966. The transistor is made of...
This 6-transistor Japanese radio from the 1960s used germanium transistors and had an output power...
The waveform generated by this circuit produces a sound similar to that of a bird. The circuit is based...