The selected circuit is from the Texas Instruments optoelectronics manual. With it you can receive optical signals in CW. Transistors support equivalents.
This circuit is from Motorola documentation on 1976 power devices. SCRs are powered according to...
Assembled with SMD components this spy can be made very small. We found it in an Australian...
We found this circuit in an old documentation. The operational amplifier of the time can be...