This circuit uses a dual-gate MOSFET, a rare component today. We found it in American documentation from the 1980s. The rest of the components are common.
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...