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 electronic voltmeter circuit was found in a documentation from the 50's. The sensitivity is...
In this oscillator a phase shift network formed by C1, C2, C3 and R1, R3, R4 determine the fase...
This circuit monitors the current of a series of 40 V lithium battery packs connected in series....