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 counter performs the same function as the 4020, but includes an internal oscillator. The...
This circuit was obtained in a Popular Electronics of the 90s. It against a kitchen hood based on...
This circuit is from a 1980s Signetics documentation. The circuit separates the modulation signal from a...