Re: [CAD_CAM_EDM_DRO] Power Supply

The transformer output will always be higher on no load and will sag on
load. By how much will depend on its "regulation" generally speaking
dependent on how much iron there is in it. If you know what the average
load is likely to be you could make a dummy load and test it. I would
expect that you would definitely need a higher no load output than under
normal running conditions in any case.

Also, if you smooth the output with capacitors, as I would expect to be the
case, the no load output would be higher again. Depending on the size of
the capacitor that could affect the regulation as well.

Your question ties in a little with my own query a few days ago about a
power supply. No responses here but I have since found that the Darlington
I require is a BDX33c, a 10 amp device. It is set for 39V but if you need
only 24V then it is not difficult to add a small regulator to knock it
down, in similar fashion by having a 24V zener in the base connection.


John Brouwer



Rob wrote,

>Hello all. I am newbie to this group, have lurked for a while and
>now going for my first post. I am retrofitting an early 80's
>Bridgeport Seriies II that had a BOSS 9 control. I am using Rutex
>servo drives and plan on running Mach2 control software. My
>question has to do with the DC power supply that the machine came
>outfitted with. I hope to reuse it as it seems to fit my
>power/voltage requirements and it would save me money. My problem
>is that I am getting some higher than expected voltages out of the
>24 VDC bridge rectified supply. I would like to continue to use
>this to power much of my air systems and to supply the control
>voltage to the Rutex cards. I have 247 VAC coming from my single
>phase mains. This is higher than the 230 VAC that the machine is
>set up and transformers tapped for. My father works for the local
>power company and says that I live very close to the sub-station,
>thus the high main voltage that I will have to live with. My supply
>is set to accept 115VAC from a transformer and turn it into 24VDC.
>I am getting 127 VAC or so from the transformer and 36 VDC out from
>the supply. THis seems like a big jump out for the relatively small
>jump in. What I would like is a way to run numbers for the supply.
>I can't seem to find a good source on the net. Does anyone have any
>suggestions? The electronics books I have looked into have been
>very general, not specific enough for what I desire. Does any one
>have any suggestions in this area as well? I am open to any and all
>info, I love to learn as much as I can about this stuff, so if
>anyone has any personal knowledge or advice to share I would be much
>appreciative. I have a back ground in mechanical engineering, so
>electrical issues are not my expertise. My schools cross over
>classes for us mechanical guys into electrical was lacking to say
>the least. Thanks in advance for any advice or info. I look
>forward to the many great post of this group in the future. Keep up
>the good work.
>
>-Rob
>
>
>
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