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 suggested by Texas Instruments in a manual of operational amplifiers. Other...
Found in American documentation from the 1980s, this circuit shows how to use an LM3909 pulsator in a...
This circuit was found in an Elektor from the 90s. The integrated circuits are not very common...