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.
An oscillator that can be frequency controlled by a resistive sensor is shown in the figure. The...
The idea of this circuit from a 1960 publication is simple: we can switch the transistor being...
This circuit was found in a Radio Electronics from February 1966. With it it is possible to trace...