RE: [CAD_CAM_EDM_DRO] Re: Stepper Power Supply. Question about Voltage

Try 1k 5watt resistor, that is what Dan Mauch told me to use.

John Guenher

> -----Original Message-----
> From: kaynrc [mailto:tom.kay@...]
> Sent: Friday, January 18, 2002 4:35 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] Re: Stepper Power Supply. Question about
> Voltage
>
>
> Hi all
>
> Guess, what? I hooked up the cap, and the reading was 39.1 VDC. You
> guys were bang on ! Well done.
>
> Thanks a lot for the replies, and no doubt, there will be more
> questions as time goes by. It will be interesting to see how much the
> voltage drops, when I apply the load (the stepper motor). I
> discharged the cap each time I unplugged the unit, by shorting it
> with a pair of pliers, and ZAP ! I think I will add a bleed resistor
> just to be kinder and gentler, but I'll have to figure out what
> resistance and wattage.
>
> Cheers all, this group is great. Tom Kay, Ottawa Canada.
>
>
>
> --- In CAD_CAM_EDM_DRO@y..., "kaynrc" <tom.kay@n...> wrote:
> > Hello
> >
> > I am just getting around to selecting some transformers to build
> > sparate little power supplies for Dan Mauch's 5 amp boards, and
> each
> > transformer is rated at 26 VAC, 5 amps. I plugged one in, and read
> it
> > at 29.2 VAC, which is fine by me.
> >
> > Then I connected the bridge rectifier and got a surprise, which is
> a
> > reading of 26 VDC. I had not yet hooked up the 10,000uf, 50 VDC
> > capacitor. Because the VAC is supposed to be higher than the VAC
> (by
> > a factor of 1.41) I expected the DC voltage to be higher, around 35
> > to 39 VDC. Again, it might be important that I did not attach the
> big
> > cap yet.
> >
> > So, what's going on? Will I notice a voltage increase when I add
> the
> > capacitor? Why is my DC voltage so low just taken right off the
> > rectifier, since it's only suppose to consume around 1.7V? Is the
> > transformer perhaps too small to supply proper voltage? And last,
> > these 521 oz-in motors that I got from Camtronics (and the circuit
> > boards) can run up to 40VDC, so am I simply going to operating
> slower
> > with somewhere around 25 to 30 VDC? Noticably slower?
> >
> > Thanks, Tom.
>
>
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