This circuit was found in a 90s Electronic Engineering. The quadruple operational amplifier can be replaced by an equivalent. RL determines the tested resistance range.
As we have explored on this site many times, a 2N3055 without the cover works like a low yield...
This circuit is for a siren that can be used with any of the above alarms and also other types. The...
This circuit triggers when the test leads are exposed to moisture or water. The circuit is from a...