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 is from a Motorola integrated circuit manual. The integrated used is no longer common...
Found in a 1968 US publication, this circuit is designed to measure very weak signals. The...
This circuit was found in the Intersil Databook. The integrated circuit used is uncommon today. R2 sets...