HJR-4102L 12V Relay Pickup/Dropout Sweep

Application

This circuit sweeps the relay coil voltage from 0 V to 12 V while the SPDT contact switches a 5 V signal between normally-closed and normally-open loads.

Design Context

The coil branch is separated from the contact branch so the electromechanical control path and switched load path are easy to compare.

Expected Behavior

As coil voltage increases, the NO and NC output voltages show the contact transfer around the model pickup threshold. The coil-current trace gives the corresponding drive current.

Suggested Experiments

• Reduce VCOIL and compare pickup behavior.
• Change RNO and RNC to see how the switched loads affect node voltages.
• Use the coil-current probe to estimate relay drive requirements.

Featured Component

HJR-4102L 12V Relay provides the coil-controlled SPDT contact. COIL+/COIL- drive the relay, while COM, NO, and NC form the isolated switch path.