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.
Found in a 90s R-E Experimenter Handbook, this amplifier uses an integrated circuit from that...
We found this oscillator in an English documentation from 1977. The symmetrical supply, in fact,...
The circuit shown here produces a pure square tone of 440 Hz that is suitable for musical...