OpenEuphoria

Re: error

• Posted by Kat <gertie at PELL.NET> Aug 12, 2001
• 484 views

On 11 Aug 2001, at 20:49, rforno at tutopia.com wrote:

> > 
> Kat:
> Sometimes I have noticed a power drop lasting perhaps 1/10th of a second in
> the
> room lights, that did not affect the PC. This is much more than your 1/120th
> of
> a second.

You must not have a very loaded computer. I have 3 harddrives which get 
used often enough that they never sleep 24-7, etc etc.. Could be you have a 
problem with the room lights too, or that power circuit.

> This is because the AC power is rectified and stabilized in the power
> source inside the computer, where there is a capacitor that can hold the
> low-level voltage for a fraction of a second. But if the outside voltage is a
> bit low, when it drops more for let's say one or two seconds, it may cause the
> PC to reset.

Thats cute, hun.

To make this short, i know what a capacitor is and how they operate and 
their ratings. That fraction of a second can be remarkably short.

There is no way you will get a desktop puter to stay awake thru a 1 sec 
power blackout, with the harddrives running, on a standard PC power supply. 
The secondary side caps are there more for filtering than bulk storage, the 
primary side caps are as small as possible to make the supply cheaper. 
Rule of thumb: if the 120v power skips *one* cycle, the puter is in trouble,, 
and 99.9% of the time, you can count on it crashing if two are missed. I have 
watched on the scope as cheaper supplies went out of proper regulation if 
*1/2* of a cycle got clipped. This also depends on the powerline, how much it 
charged the primary side caps before the power was cut, the cap's ESR, 
circuit design, etc... Your mileage may vary, but i swear *by* the battery 
backup supplies, and i swear *at* the power companies.

And by the way, *most* equipment power supplies use only the peak of the 
sine wave, and i have seen many times, on outdoor stage events, when the 
power amps clobber the line peaks, the mixer or other equipment screws up 
royally. Puter power supplies also use only the peaks, and if that *peak* 
drops below 130v, it's useless as the supplies are designed, even if the lights 
are still on.

Kat

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