Re: [CAD_CAM_EDM_DRO] power supply

Peter,

You need to take into account your local line voltage. One of the problems
in our area is that the line voltage may be as high as 124VAC. I had a
transformer built one time and I specified the input as 110VAC. When I went
to use it my DC output was higher that I wanted. The problem was that my
local line voltage was around 124VAC, not 110VAC. The extra 10 or 15% can
make a lot of difference.

Why do you want a zener diode across the output for a power supply that you
are going to use for a stepper supply?

You should use a bleeder resistor across your DC output to bleed the output
when the power is turned off.

Bob

----- Original Message -----
From: <cadcamcenter@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, October 16, 2001 12:31 PM
Subject: [CAD_CAM_EDM_DRO] power supply


> How dependable are transformer specs?
>
> A Single phase 0-115-230V primary 24VAC secondary connected to a
> bridge rectifier and 15,000uF capacitor should produce 33 VDC. The
> actual output was 46VDC. The culprit? On checking the transformer
> secondary, the output was 33VAC instead of the specified 24VAC. Is
> this common experience?
>
> Based on what had been so emphatically put across recently, one
> should have no hesitation on using this power supply despite it being
> out of specs - voltage being so unimportant for steppers, right?
>
> Just to be on the safe side - what size zener diode should one place
> across the output?
>
> Peter
>
> BTW one should take care to discharge the capacitor, say, across an
> incandescent lamp at end of test.
>
>
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