Mains Tester cum Night Lamp. Home Utility Circuit 20

MAINS-MONITOR-2Here is a dual purpose LED light powered directly from 230V AC. It indicates whether power is available or not in the Three pin socket. Its second function is that, it is a very good Night lamp giving sufficient light in the room. If it is plugged in the Mains box, it shows whether domestic power supply is present or not and also gives light in the Mains box to work in night. Its cost is just Rs. 15.

Designed and developed by D.Mohankumar

You need the following components
1. 22K 1 Watt Resistor – 1
2. 100 Ohms ¼ Watt Resistor -1
3. 22 uF 25V Electrolytic Capacitor -1
4. IN4007 Diode – 1
5. White LED 5 mm – 1
6. 3 Pin Plug – 1


How it works?

SHOCK-HAZARDWarning! This circuit  uses 230 VAC and exists at Lethal potential that can give a Fatal shock if touched. Build this circuit only if you are competent to handle high volt circuits. If you are a beginner and not familiar with AC circuit, leave this for safety.

Take all adequate safety measures during its testing. Test only after closing the case. Troubleshoot only after removing from the Mains.



This circuit directly uses 230V AC and built as a Resistive Power supply. The 22K 1 Watt resistor drops the high volt AC to low volt AC. Diode D1 rectifies the low volt AC through half wave rectification. Capacitor C1 removes ripples from the DC thus available. This low volt DC is used to light the White LED. Resistor R2 forms the current limiter for the LED. Thus it acts as the Main indicator confirming that both Phase and Neutral are available in the Socket.