This circuit acts on a relay disconnecting the load when the input voltage exceeds the set limit. The transformer is 12 V secondary according to the relay used.
In the figure we have the way to use a common operational amplifier for AC signals. The resistor...
This configuration presents a negative resistance caracteristic such as the one found in...
The transistors of this circuit found in a 1965 magazine can be the BC558 and the sensitive 12 V x...