This circuit was obtained in an Electronic Engineering of the 90s. The operational amplifiers and the sensor are from that time. The circuit has symmetrical power supply.
Found in a 1980s American documentation, this crystal-controlled oscillator generates 100 MHz...
We found this circuit in a 1980 publication. It can be applied to Triacs of the TIC series and the...
We found this circuit in an old documentation. Transistor can be BC548 and relay according to...