This Linear Technology circuit can measure currents from 100 pA to 100 uA. The circuit is from the 80's, using a component of the era. Transistors are general purpose types.
This field strength meter for the 11-meter range was found in Radio Electronics magazine from...
The output stage of this amplifier can operate at high voltage. The transistor must be a high...
This article is from an old publication from 1978. The transistor can be a BC548 and the power...