We found this circuit in an old documentation. It can be elaborated based on modern components. The double transistor can be replaced by a matched pair.
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...