Re: [CAD_CAM_EDM_DRO] Re: Power Supply-- more questions

>I can't quite get 25 times my stepper voltage as that would put me over the Gecko 80v rating. So I'm shooting for 78vDC to the drives. Therefore 78/1.4=56vAC 6.0A x 4 steppers =24A.
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an unregulated powersupply will run at more than the rated voltage under
no load. so if the 80V is an absolute maximum limit for the geckos it
will be a little dangerous to design for 78VDC.
I think I use a transformer with 48VAC (2x24 in series) as the secondary
for my gecko system.
remember you will lose the two diode drops at the diode bridge.

>I have no idea if the above will work.. ok.. or if I'm totally off base. They want $41 CAD each. I would need two of them wired in Parrellel?? Also wondering about what make [material] the proper CAP should be made from.. as there seem's to be several choices? What got me looking at these ones was simply that they "looked" like one's I've seen in others project pictures.... The are Panisonic and are called "Computer Grade Capacitor's"
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large caps are always electrolytic (they have polarity and will not like
being hooked up the wrong way!).
more expensive electrolytics have higher brake down voltage, higher
temperature resistance, and less leakage current.

>Next on the list is the Bridge Rectifier.. I don't think there is alot of science for these, I chose one, 35A @ 100V, 400A Max surge, 10.0 uA Max reverse current, 1.1V Max forward volt [peak] They want $4 CAD. [ Digikey also]
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that's probably ok.

>Is there anything else I missing? I seem to remember someone putting various other Resistors and what not in theirs.. ??
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the filtering caps will retain their charge for a long time when you
turn off the system unless there is a "bleed/discharge" resistor across
them. So for example turning off the machine and letting it stand for
half an hour and then opening the case could still be a shocking
experience. Choose a fairly big resistor so that the wasted current
through the resistor is not high. The caps will completely discharge in
about 5*R*C seconds so on the other hand if you choose a too large
resistor it won't help very much.

DPST switch for the primary, a fuse !, panel meters for voltage and
current are nice
If you are afraid of voltage spikes etc.(lightning) in your electricity
network then put some protection components over the primary.
If you are worried that your cnc machine might disturb other sensitive
equipment around it through the electricity network then probably an RF
filter on the primary is a good thing.