This circuit was obtained in a 1968 manual of General Electric. The components used are of the time, but they admit equivalent. Observe the optical feedback system for control.
This amplifier can be powered with voltages between 2 and 5 V with power up to 100 mW. The minimum...
In the figure we have the way to control a TIC series triac with a reed switch. The current in the...
This practical idea from a 1992 documentation shows how to count the turns of a winder using a...