This Schmitt optical trigger with LDR was found in old documentation. The relay must be sensitive, or an additional step must be used to trigger it.
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...