In use telephone indicator (CB8665E)

This circuit was found in a 90s Electronics Now. The circuit can use a TIC106 for the SCR.

Relay Drive AC Stage (CB12182E)
With this circuit, a relay can be activated from an alternating signal with frequency up to a few...
Visually Impaired Electronic Guide (CB18123E)
With this circuit the visually impaired can easily locate important places inside the house, such...
Schmitt trigger (CB21475E)
In the figure we have the way to use the transistors of an old-paired pair as a trigger circuit. The...