This automotive grade circuit was found in a 1991 Electronics Hobbyist. The transistors are general purpose types. P1 sets the monitoring voltage.
The integrated circuit used in this project is unusual. However, we can take advantage of the...
This circuit has 4 operating modes and was found in the 1995 Encyclopedia of Electronic Circuits...
The transistor of this oscillator can be 2N2222. L1 is formed by 9 turns of wire 26 with a socket...