Arduino Arc Welder That Runs Continuously

A tutorial, sketch and wiring diagram for making an arc welder using a  standard white LED.

The arc welder in this sketch runs continuously, randomly flashing  LEDs.

The Arc Welder Sketch

For your convenience, sketches are stored on Pastebin.  This will take you to Pastebin where you can review, print, embed and download the sketch.  Arc Welder Sketch


Materials Required

Arduino Nano – You may also use an UNO




LEDs – The basis welder uses two white.  We show yellow here so that you can see it against the white background.

You may increase the number or LEDs and/or change the colors.






resistorsResistors – Equal to the number of LEDs.




prototype board


Prototype Board – i piece





All the parts shown are readily available.  For your your convenience, however, You may get a cost and time saving kit to make this at Kits.

Arc Welder Demonstration

In this short video to make the flashing visible have used yellow LEDs . We normally use white. Some folks use a blue marker to cover part of the LEDs with blue.

You may also add a third LED.

The video doubles as a wiring diagram.


This simulation was done using WOKI.  It is a free code simulator with extensive capabilities and help.l


The Arc Welder Wiring

arc welder wiring diagramA resistor of about 220 ohms is typically fine. Vary your brightness by using a resister from 150 ohms to 560 ohms.

Wire from a telephone cable is fine.

We recommend using an Arduino Nano.  The nano is cheap and small.

Power the Nano by attaching a 7 to 12 volt power supply to the Vin pin. Actually, some people use 3 AAA batteries . 4 is better.  The square 9v batteries have very low capacity so use the AAA batteries.




Getting Parts

Getting parts can take a lot of time if you get them from the Far East, assuming you get good quality, or they can be rather expensive it you buy them one at a time.   Kits are cost saving and everything comes to you at once.  And these are shipped  Europe and the US. And the materials have been approved for quality.  Look at them at This Page.



Arc Welder Library

There are all the arc welder sketches available.

Arc Welder That Runs Continuously  – Simple but effective and easily modified.

Arc Welder Switch Controlled.  –  Turns welder on and off using a simple toggle switch.

Arc Welder Timed Operation –  The arc welder will start and stop on a time schedule that you set.



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