This untuned circuit uses one of the world's first commercial transistors, the CK722, having been found in a 1966 publication. Equivalent modern types can be used.
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...