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.

Arc Welder Library

There are other arc welder sketches available.

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.


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





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 12volt 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.




You may get a cost and time saving Kit to make this at Kits.


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