This circuit is from a 60's documentation. The capacitance C1 can be between 20 pF and 0.01 uF depending on the generated frequency. Equivalent transistors may be employed.
This circuit was found in an old documentation from Europe. The integrated circuit used is...
I found this circuit in a Popular Electronics from November 1999. The magazine is no longer...
This photometer is based on a Wheatstone bridge that must be balanced by the linear potentiometer P1. The...