We found this circuit in a spy book from the 90s. Transistors admit equivalents and the coil can be designed as in the CB19425E project. Power is provided by cells or 9 V battery.
With this circuit, a relay can be activated from an alternating signal with frequency up to a few...
With this circuit the visually impaired can easily locate important places inside the house, such...
In the figure we have the way to use the transistors of an old-paired pair as a trigger circuit. The...