Re: calculating ripple

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Ken,

Unless you are working with just resistors or some other "really simple"
system, I don't think any "simple equation" will work.  You probably need
to know RMS current, peak current, and maybe turn on currents...

I do this very thing for my OLTC coil, but I use MicroSim to crunch to
numbers directly.  Here is the schematic:

http://hot-streamer-dot-com/temp/OLTC08-22-01.gif  

I charge Cp through a bridge and resonant charging circuit.

Suppose I need to know the peak, RMS, and turn on currents for Cp.  There
is no equation here...  Even a high powered EE math type person would
probably not be able to do it (especially the RMS current) with just a
calculator and paper.  If they do try to work it out, you get a bunch of
"opinions" as you have found :-D  Real "build it and test it stuff" could
get very expensive and frustrating...  What they really do is build the
thing and use one of these ;o)

http://hot-streamer-dot-com/temp/OLTC08-22-03.jpg

Or, if your a lunatic Tesla coil builder who HAS to have everything.  You
could get a setup like this ;o))

http://hot-streamer-dot-com/temp/OLTC08-22-03a.jpg

But today, "anyone" who reads at least a few of the instructions can click
the thing into MicroSim and get your answer:

http://hot-streamer-dot-com/temp/OLTC08-22-03.gif

106.152 Arms
2010.6 Apeak
No transients from turn on.

The free demo version of MicroSim and the instructions are at:

http://hot-streamer-dot-com/TeslaCoils/Programs/91pspstu.exe

http://hot-streamer-dot-com/TeslaCoils/Programs/pspcref.pdf

Even a dummy like me can look smart when you have MicroSim giving you all
the answers 0;-)  What is really cool, is that it really does work
extremely well.  The OLTC real waveforms are exactly like the MicroSim
model predicts.  I have blown up a lot of things "virtually" in MicroSim,
but I have not blown up any real hardware with MicroSim there to tell me
when to be careful...

If you are asking questions like this a lot, take a little time to learn
about MicroSim and you will know as much as anybody :-))

Cheers,

	Terry




At 10:00 PM 8/21/2002 -0500, you wrote:
>How do some people here calculate ripple on a capacitor being charged at
>120Hz from a bridge rectifier and a load of x amps? So far every place I've
>looked has a different formula, and none have consistent answers.
>
>- the Rado Shack "Building Power Supplies" book suggests
>
>   Vrms = 2.4 I/C
>
>where Vrms = ripple volts
>2.4 comes from apparently nowhere
>I = current in mA
>C = capacitance in uF
>
>- this link on audio amplifier design says
> http://sound.westhost-dot-com/power-supplies.htm#capacitor-value
>
>which comes to a different answer yet again.
>
>- another link has something similar
>http://www.mitedu.freeserve.co.uk/Circuits/Power/unreg.htm
>
>- and one more
>http://my.integritynet-dot-com.au/purdic/power1.html
>
>and the botton of the page here
>http://www.signaltransfer.freeuk-dot-com/powerout.htm
>
>So, what should I use, and where do these strange numbers like the "factor
>of 7" for 60Hz and "2.4" come from?
>
>KEN
>