This circuit was found in a 1975 documentation. Current general-purpose transistors can be used, and the power is supplied with relatively high voltage. The gain is 30 dB.
This photometer is based on a Wheatstone bridge that must be balanced by the linear potentiometer P1. The...
Utilizing the MAX4172 or MAX495 integrated circuit, this circuit increases the sensitivity of a...
The article that teaches the assembly is from a Radio Electronics issue from July 1969. The...