Re: [CAD_CAM_EDM_DRO] Welder as a power supply transformer

Robert Allen & Marsha Camp wrote:

> I have a 130A sears ac welder that I bought for $10 at a
> yard sale. As a welder it is a piece of junk, it welds and
> the amps are OK but compared to the Millers we have at work
> it is not very good, so I was thinking to use the
> transformer for my power supply for a Gekko G320 servo
> setup. I haven't taken the cover off recently but I believe
> the windings are aluminum and the transformer is multi
> tapped therefore making the voltage adjustable. I was
> wondering if anyone has any thoughts or experience with such
> things?

Buzz-box welders are not really classic transformers. They have a high
leakage inductance designed in, to limit output current without depending
on winding resistance. Unfortunately, this means that the voltage output
depends on current drawn. Now, the stepper drivers will draw so little
current that it woun't cause much of a voltage dip. The transformer
usually only has two taps, High and Low amp range. The rest is done
by moving magnetic shunts. These things draw a lot of power, at a
hideous power factor, therefore, huge amps. Sure, if you want to have
a 240 V 30 A + feed to run a couple stepper motors, it could be made
to work, but a 5 - 10 Lb transformer that you could hold in one hand
would work just as well, or better! I wouldn't do it just because of the
darn BUZZING!

Jon