This is a very useful autotransformer circuit on the bench. We found it in the September 1970 Radio Elecronics magazine. The transformer must be according to what you want to feed at the output.
In the figure we have a simple logic level indicator for TTL circuits or powered by 5 V....
This circuit was obtained from the December 1990 issue of Radio Electronics magazine. The circuit...
This power supply for gas laser (HeNe) was found in a 90’s Popular Electronics. It generates from 1300...