We found this good amplifier in a Japanese publication of 1966. Transformers are uncommon nowadays and the power supply is included. Power is a few watts.
We find this current meter circuit from 0 nA to 200 nA in a Linear Technology application manual....
In the figure we have a way of obtaining a 13,2 V with current up to 5 A using an integrated 7812...
This circuit was obtained from a 2005 Linear Technology manual. The circuit is self-powered and can...