on video AC line detector circuit. AC line checker use 2 transistor.

 AC line detector circuit. AC line checker use 2 transistor.

AC line detector is a device which detects AC line currents without making any electrical connections to the line.

An easy to make circuit to identify the line and the neutral of an AC circuit, without making contact with the wires.

I attached the PCB layout, you can etch the pcb.

You can download complete pcb schematic here

To know how to make a pcb

Install the components as per the layout.

Solder it carefully, because this circuit is highly sensitive.

While making my previous Instructable (easy infrared proximity sensor) I figured out a few things about using 2 transistors in a row to amplify a very weak signal. In this Instructable I will elaborate on this principle which is also called the "Darlington principle".

In this circuit, an antenna (spring) is connected to the base of first transistor. When we place this antenna near an object that is AC energized, a small current gets induced into the antenna due to electromagnetic induction. This current triggers the first transistor. Output of the first transistor triggers the second. The second transistor switches on the LED indicating that AC voltage is present.

 AC line detector circuit. AC line checker use 2 transistor.

AC line detector is a device which detects AC line currents without making any electrical connections to the line.

An easy to make circuit to identify the line and the neutral of an AC circuit, without making contact with the wires.

I attached the PCB layout, you can etch the pcb.

You can download complete pcb schematic here

To know how to make a pcb

Install the components as per the layout.

Solder it carefully, because this circuit is highly sensitive.

While making my previous Instructable (easy infrared proximity sensor) I figured out a few things about using 2 transistors in a row to amplify a very weak signal. In this Instructable I will elaborate on this principle which is also called the "Darlington principle".

In this circuit, an antenna (spring) is connected to the base of first transistor. When we place this antenna near an object that is AC energized, a small current gets induced into the antenna due to electromagnetic induction. This current triggers the first transistor. Output of the first transistor triggers the second. The second transistor switches on the LED indicating that AC voltage is present.