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Author Topic: How to correctly ground very noisy spinddle  (Read 5154 times)

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Offline rcaffin

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Re: How to correctly ground very noisy spinddle
« Reply #10 on: July 08, 2014, 05:18:03 PM »
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Since the supply(s) are already rectified within each series supply, you're not dealing with the spikes that occur from the bridge mains rectifiers -  so a 200VDC electrolytic filter capacitor will be just fine at the 90 DC volts
All of that would be correct if the laptop supplies are simple linear jobs. But since there seems to be a of of RF around, I question that assumption. My experience has been that in order to get an input rating of 100 - 250 VAC, which most of them have these days, they use a switch-mode supply (SMPS). I have a tiny charger for a camera battery from eBay which cost me just $5.05, and it too has an SMPS in it. Dunno how they do it for the price.

Cheers
Roger
Re: How to correctly ground very noisy spinddle
« Reply #11 on: July 08, 2014, 08:42:27 PM »
But then look at what is being done with this supply (or supplies in this instance).... whether they are a group in series or better yet one switching power supply of ample power, the ultimate use is as if it is a linear supply of varying load. If we were charging a battery - OK; or a fixed load - OK. But he's attempting to run an electric motor with a group in series of switching supplies. They still will need to be filtered as if it was a linear supply and even very much more so in this instance. These type supplies are designed for specific loads and specific variables in load but keeping the load demand in mind as has apparently been accounted for, all we need to do for Adrian is help him quiet down the effects of running a DC motor on his group of switching power supplies..

I will respectfully bow out of this....

Sorry Adrian, just attempting to help you out. My experience with power supplies of all types goes all the way back to the thyratron tubes that Monarch used in their EEE lathes, which I serviced and maintained for years. Computer supplies are a shortcut in technology to satisfy a narrow line of demand and price. 'Simple' linear supplies are not so lost in the mist of current thinking - might be some lack of experience or respect.

Thanks,
 Bill C.

Offline rcaffin

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Re: How to correctly ground very noisy spinddle
« Reply #12 on: July 09, 2014, 12:09:56 AM »
The bottom line in all of this is that power supplies are not the simple beasts they are so often made out to be. Without being able to look at Adrian's system with a CRO, it is very hard.

I do remember listening to a conference presentation on a 5 V 600 A PS once - it was for a rather large computer (and no, there are no typos there). The complexity needed in the design was ... iinteresting!

Cheers
Roger