Building a HF start box

Metalworking Technology Workshop
Building a HF start box

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

  1. Tom says:

    Is the 3µF 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.

Comments are closed.


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. And he has a new best-of writing collection and “lazy man’s memoir,” called Borg Like Me.

View more articles by Gareth Branwyn
Send this to a friend