This circuit uses a photo-SCR or LASCR that is not a common component today. The relay depends on the load, and the power is supplied by the power grid.
This short-range experimental transmitter emits a signal with many harmonics, without modulation. It can...
The LM380 is not a modern component and in some cases not easy to find. But if you have one you...
This is the analog part of the previous circuit with the pressure sensor for the altimeter. The...