This constant current charger from 1997 Linear Technology Applications uses common components at the time. The transformer is the critical component, being designed according to the load voltage.
This circuit was obtained from a 2005 Linear Technology application manual. The circuit is...
Frequencies from 1 to 10 MHz can be obtained with a small adjustment of the variable in a narrow...
Found in a 1980s American documentation, this circuit uses programmable unijunction transistors of the time....