This circuit is from Philips' 60s documentation. The circuit can be applied to modern operational amplifiers. The power supply must be symmetrical.
This circuit was found in a 1992 documentation and has excellent sensitivity, using components that...
This practical idea from a 1992 documentation shows how to count the turns of a winder using a...
In this circuit from the 60s, the power supply is made with 22.5 V, which is the voltage of the...