This circuit is from an old Mullard (Philips) manual with applications using the 555. Choosing appropriately the resistors and the timing capacitors, the ranges obtained can exceed days.
This circuit makes use of a low impedance microphone. The relay is according to the supply voltage...
This circuit behaves as a voltage controlled resistor and can serve as a small load. The circuit is...
The purpose of this project is to monitor remote loads. The windings are made in a burnt...