DIY Non Contact Voltage Detector


DIY Non Contact Voltage Detector will be our interesting topic for today, Hi maker’s welcome back, I hope you’re fine so today we will learn something new!

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what is non contact voltage detector

This is a Voltage Detector use to detect the AC voltage, I thought this is  very simple circuit to do it since it consists of few electronics  components.

we will only need some resistor and some transistors to increase the current that enters through the base of one of the transistors.

its power supply is a 9V battery.  These devices are generally of the capacitive or resistive type, in our case it is resistive.    

In this article, the author of the YouTube channel “DIY Pro” will  show how you can make a simple hidden wiring detector.

Materials for DIY Non Contact Voltage Detector

  1. Li-ion battery 9V 
  2. C945 transistor
  3. 1kΩ resistor
  4. LED
  5. 0.5 mm enamel copper wire
  6. Some wires.


  1. Soldering Iron
  2. – Tweezers
  3. Third hand

So, the main elements of this device will be three C945 transistors.

The C945 transistors can be replace with 2SC3198, 2SC1815, KSC1815, KSC945C, KTC3198, C1815.

(You can use whatever you get out of this, I use C945)

What Is C945 transistor

C945 is a general purpose NPN transistor, widely used in various commercial and educational electronic circuits. this transistor is commonly use in electronic circuits that require high-speed, low-current transistors.

C-945 has three semiconductor regions the emitter, base, and collector, because c-945 is a bipolar junction transistor,

its base is doped with positive or p-type semiconductor materials.

The emitter, collector and base pins will be connect as follows


The indicator will be a regular red LED. The long leg is a positive contact.

  • You will also need a 1kΩ resistor and a 9V battery with connector.
  • The antenna requires a piece of copper wire with a diameter of 0.5 mm.
  • This piece of wire is wrap around a pen or bamboo skewer.



According to the diagram, the LED is solder. 

Now, fixing the all components in the “third hand” clamps , the author solder together the emitters and bases of the transistors.

A resistor is solder to the emitter of the first transistor everything is ready, you can connect the device to the battery.
As you can see, when the coil is brought up to the power cable, the LED lights up 

working video of DIY Non Contact Voltage Detector


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