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 the transmitter of a data transmission system with optical fiber suggested by...
This circuit was found in a 1969s American documentation. With modern components, it can be used...
The maximum input voltage of this circuit is 20V and the output current is 250 mA. The circuit is from...