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 VCO makes use of components from the 1980s. The circuit can be implemented with modern...
This circuit uses an LDR as a sensor to trigger an LED indicator at a preset lighting level. The...
This circuit was found in a 1968 General Electric documentation. It has an input impedance of 2 M ohms...