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.
This receiver is from a 1967 Japanese publication. The transistors are germanium and the output...
The basis of this project is a three-position lever switch or similar. When the switch is in the...
The astable multivibrator shown by the figure can produce signals in the 10 to 10 000 Hz band...