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

Tom,

I just had essentially the same experience. When I hooked up the 15,000uf
capacitor I have, the dc voltage went to 39.6 volts, with no load. What I
believe happens is the dc voltage is essentially a pulse stream without the
capacitor so the meter can't get a good read of it. The capacitor smoothes
it out greatly.

John Guenther

> -----Original Message-----
> From: kaynrc [mailto:tom.kay@...]
> Sent: Friday, January 18, 2002 1:40 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] Stepper Power Supply. Question about Voltage
>
>
> 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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