This amplifier for electrometer can work with currents of 0.1 pA in a band of 1 Hz. The circuit is from NASA in a publication of the 60s. Transistors are general purpose types.
The circuit shown is from the Motorola Linear Databook from 1990. The circuit has two outputs with...
This rejector filter that was found in a 1980 documentation uses an operational one at the time....
This fuse test circuit was found in Radio Electronics magazine from August 1958. The circuit was...