Relay detection circuit

Measurement coil resistance. Multimeter selection R × 100. Fig. B measures the relay suction and release voltage. Adjust the regulator power supply to gradually increase from 0V. When the armature "click" is just heard, the voltage value indicated by the voltmeter PV is the suction voltage. Then adjust the pressure regulator knob to make the voltage drop gradually. When you hear the armature click released, the voltage is the release voltage of the relay. Figure C shows the absorption current and release current of the relay. The method is similar to Figure B.