This is non-contact ac voltage detector circuit. It uses a digital-IC, CD4060 as main components, resistor and LED display only. Also, It uses 9V battery as power supply. This tool has featured the equivalent of a professional, easy to use, cheaper, and more importantly, safe for use. For checking to find AC 220 Volt or 120V or called that AC main power in various points.
Most people a screwdriver to check the electricity. It is a lightweight, easy to carry. But the users lack of knowledge or caution in use. It can be a danger easily of electric shock.
Because of the usage of a screwdriver. The small amounts of electricity to flow through the conductor and users as well. It may seem very dangerous. If a short circuit or any people touch the parts of the conductor.
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The working principle of the project
Detection of the main power uses a principle of electromagnetic fields that spread out from the wire. While the electric current flows through a conductor, wires. It will make the magnetic field.
We can detect the electromagnetic field with a high sensitivity device only.
The CMOS is a type of semiconductor device is suitable for use in this application. I choose to use the CD4060. It can generate a clock signal and divides frequency at the same time. Until an output signal is displayed by LED.
Non contact voltage detector circuit diagram
How non contact voltage detector works
If you look at the above circuit. You may shock and do not believes it will actually work. Thus, we read the principle of how it works.
When we started to use a wire antenna is a length of 10 cm. Placed near the conductor insulation. Then, the electromagnetic inducts into the clock signal to pin 11 of IC1-CD4060.
This is a CMOS as frequency generator circuit and 14 stage binary frequency counter.
The electromagnetic field from the mains power. Which has a frequency of 50HZ come to IC1. It is frequently divided out of Q4 pin of IC1. It is divided by 16, frequency equals 3HZ. So the LED1 flashes to indicate that around the mains power.
If no mains voltage or current to flow or without the electromagnetic field. The output of IC1 is not up the frequency of 3HZ. Thus LED1 does not blink. But it will light continuously or goes out non-lighting.
This detector project is also used to detect the magnetic field at various points. Such as a monitor, lamp, TV, computer and more. The flashing of LED1 may flash faster. Because its intensity of the magnetic field and a higher frequency than the mains power.
Applications of non contact voltage detector
It is so easy and safe to uses. Just you place the antenna close to the mains cable or plug socket. If it has an electric current, LED1 will flash. But if no power, LED1 is lit or shut down. As mentioned above.
Important Do not bring antenna insert holes into of plug socket into the wall outlet.
Do not bring antenna insert holes into of plug socket into the wall outlet.
The downside of this project, it cannot indicate which is Line or Neutral. But I think it is not important. Because it is good in budget. It is worthwhile to build it.
I add a buzzer circuit at the output. As the circuit below and see video show using this project.
The buzzer sound circuit is astable multivibrator with both transistors like we often use them.
All components please see in a circuit it a few parts.
My son is testing the non-contact voltage detector circuit.
When near AC-line it will alarm with buzzer sound and LED flash as the frequency of AC-line.
And can test area that high frequency or fluorescent lamp.
non-contact voltage tester using transistors
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