The circuit is from 1968, but we can use a modern one like the 741. The symmetrical power supply voltage (two batteries or source) can be from 9 to 12 V.
This circuit was found in a Texas Instruments optoelectronics documentation. The gain depends on...
Just touch the sensor and the L1 lamp will light. The circuit has no lock, which means that the...
Found in a 1970s RCA documentation, this circuit generates signals according to the component...