This circuit was found in an old American documentation. It can operate with signals from 40 Hz to 50 Hz and the input voltage range is from 0 to 200 mV.
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...