Found in Unitrode documentation, this oscillator uses some unusual components today such as PU and the 3 M potentiometer. The power can be made with voltages around 15 V.
The figure shows how to use a 3-winding transformer to switch outputs with different voltages by...
This 80's circuit, suggested in Texas Insrtruments documentation, uses a Hall effect sensor. The...
This circuit was found in a 1966 publication. Its purpose is to identify high voltages by lighting a...