From: firstname.lastname@example.org (The little lost angel)
Subject: Re: Wrestlemania Royale: Tantalum vs. Electrolytic Vs. Polys, etc.
Date: Sun, 27 Oct 2002 04:45:30 GMT
Organization: Yes please, I'm quite disorganized & lost at the moment
References: <email@example.com> <firstname.lastname@example.org>
NNTP-Posting-Date: Sun, 27 Oct 2002 04:43:36 +0000 (UTC)
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On Sat, 26 Oct 2002 20:51:04 +0100, John Woodgate
>>C= I* Dt/Dv
>That would make a mathematician's toes curl! You can't safely invert
>differentials as if they were ordinary fractions. However, in this case,
>if you get the numbers right, it works.
Well, I failed maths and physics consistently at high school
and I am certain that on several occasions I made my maths tutor curl
not just his toes alone :P
>>C= 0.2 * 0.04 / 3 = 0.00266
>So you have 200 mA flowing through your LED(s)? Lots of LEDs?
200mA is with allowance, the designed for current is around 13~16mA
through 4 to 8 LED.
>No, it can't be right, although your cap value calculation is correct
>for 200 mA and 40 ms. But your calculation shows the capacitance you
>would need to sustain the voltage to 9 V minimum for 40 ms **with the
>SMPS switched off**. Unless the SMPS voltage really dips to zero for 40
>ms or more (and you have a diode in series to stop the cap discharging
>back into the SMPS!), that's pessimistic.
Refering to the thread I asked about the transformer whine where John
Popelish mentions the discontinuous mode, I'm wondering if that's the
problem. Since when I test those LED, the PSU has got no other load
apart from its cooling fans.
So if the SMPS did switch off momentarily, it could conceivably dip
the +12V down to say 6V for a while no? Though I'm not sure how long
does it take to notice a flicker.
>Do you have an oscilloscope? If not, steal one and look at the 12 V DC
>output on its screen and the flickering LED simultaneously.
Hehehe, I'm still looking for one or rather saving the money to get a
proper one. The other problem is the flickering doesn't happen all the
time so it's a bit difficult to catch.
L.Angel: I'm looking for web design work.
If you need basic to med complexity webpages at affordable rates, email me :)