RE: [CAD_CAM_EDM_DRO] variable transformer for dc power supply

I am not sure of what isolation of a transformer exactly means. From prior discussions about unregulated dc power supplies for stepper motor drivers, a person could build their own unregulated dc power supply by basicly pairing a transformer with a bridge rectifier and a capacitor. (I have someones detailed discription of exactly how to do this but I loaned it to my partner in this thing so I don't have it in front of me
I was wondering if the variable transformer could replace the regular transformer in the power supply.
I was going to simply put a 3 prong plug onto my rectifier circuit (the diode rectifier and the capacitor etc) and then plug that into the variable ac transformer with the output of the rectifier going into my api stepper drivers.
Does isolation refer to the type of transformer. The transformer have is the same one that jameco sells http://www.jameco.com/cgi-bin/ncommerce3/ExecMacro/Jameco/searchResult.d2w/report?sort=BPA&search=169658 jameco part number 169658.
If someone could refer me to another cheap way to get power to my stepper motor drives I would greatly appreciate it.
Thanks for your replies
Troy

Greg Jackson <greg@...> wrote:Tim,

How big of a deal do you think it is? I suppose it may be more important on
a little desk top like a Sherline, but a larger machine will already have
240 VAC in the spindle motor. The iron should be grounded and any lose
wires should simply short.

Isolation is a fine idea, but I had used DC in lots of larger industrial
machines. Sometimes we let the DC float, but more often I tried to tie it
down. I like to know where things are, particularly voltages.

GTJ

-----Original Message-----
From: Tim Goldstein [mailto:timg@...]
Sent: Monday, November 25, 2002 5:40 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] variable transformer for dc power supply

Troy,

It is not safe to use the variac as the sole transformer in the power supply
as it does not provide isolation.

Tim
[Denver, CO]
Sherline Products at Deep Discount
and Mach1 CNC control
www.KTMarketing.com/Sherline

----- Original Message -----
> I am building an unregulated power supply to power my api stepper motor
drives.
>
> Does anyone know if it is ok to use a variable ac transformer as the
transformer for an unregulated dc power supply? I already own the variac
and it would save me some money and it would allow me to play around with
different voltages.
>
>
>
> Thanks in advance
>
> Troy



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