Building a HF start box

Metalworking Technology Workshop

Gareth Branwyn is a freelance writer and the former Editorial Director of Maker Media. He is the author or editor of over a dozen books on technology, DIY, and geek culture. He is currently a contributor to Boing Boing, Wink Books, and Wink Fun. His free weekly-ish maker tips newsletter can be found at garstipsandtools.com.

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January 20th, 2009August 31st, 2015 2

A high-frequency (HF) start box is a device used in AC arc welding that allows you to start an arc welder without having to “scratch-start” the arc. You used to be able to buy such an add-on device; apparently, they’re now hard to find. William F. Dudley Jr. decided to build his own and shares the details on his project page.

[As with all high-voltage projects, the usual warnings apply (as in: don’t try this at home unless you’re familiar with HF and know what you’re doing).]

High-Frequency Start Box

2 thoughts on “Building a HF start box”

Tom says:

January 21st, 2009 at 12:18 am

Is the 3ÂµF 400V optimised for 240V 50Hz or 120V 60Hz operation of the ignition coil?

The capacitive reactance at 50Hz would be a bit over 1K Ohm giving about 230mA into the coil. Too high?

I would have asked the project designer but couldn’t find any contact details on his pages.

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Tagged welding

Building a HF start box

By Gareth Branwyn