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Old 13th May 2005, 07:30 PM   #11
simon5 is offline simon5  Canada
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Could he use BCAP0010 Ultracapacitors?

5 in series would give 520 Farads, I think he'll stay over 12.22 volts.
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Old 13th May 2005, 07:44 PM   #12
tiroth is offline tiroth  United States
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Adding more capacitance doesn't help unless your transformer/recitifiers can supply infinite current. Adding more capacitance just changes the conduction angle, which may not help you if you are already pulling down the tranny's voltage. You need to start with more voltage.

The 1.4x rule is only true if you are drawing lightly on the supply. As load increases, you begin to get only 1x RMS, and then even less than that as impedance losses add up.
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Old 13th May 2005, 07:53 PM   #13
tiroth is offline tiroth  United States
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As an aside, you can see why no one uses linear supplies to provide this kind of amperage. The losses are a lot lower in a SMPS and the regulation a lot better.
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Old 13th May 2005, 07:53 PM   #14
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Use shottky diodes.

I have the same sort of situation with my electrolysis supply, I just paralleled some dual diodes (40A 30V) from switching power supplies and it gets about 5Vrms at up to probably 50-100A.

Ultracapacitors are NOT designed for filtration, except maybe if you use a filter inductor. Think of them as fast batteries.

Tim
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Old 14th May 2005, 12:22 AM   #15
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what if I had 2000VA of toroidals, and only put the same 80amp load on them, are you saying I still wouldn't get 12volts, as I am only starting with like 12.7 unloaded?
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Old 14th May 2005, 12:54 AM   #16
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skinnyboy:
what if I had 2000VA of toroidals, and only put the same 80amp load on them, are you saying I still wouldn't get 12volts, as I am only starting with like 12.7 unloaded?
-------------------------------
Hi skinny, you would use a 2000va instead of a 1000va that is specified for the
job just to get a 0.7v better regulation, gee you are smart, i would suggest you
used a 3000va to get even better results
you would get better regulation thats for sure but the returns are small there are
better ways to tacle this problem without regulation, put load and Vtr into the
equation and save the capacitance for filtering
cheers
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Old 14th May 2005, 12:56 AM   #17
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Quote:
Originally posted by mastertech
Hi skinny, you would use a 2000va instead of a 1000va that is specified for the
job just to get a 0.7v better regulation, gee you are smart, i would suggest you
used a 3000va to get even better results
you would get better regulation thats for sure but the returns are small there are
better ways to tacle this problem without regulation, put load and Vtr into the
equation and save the capacitance for filtering
cheers

umm... wtf is your problem? I asked a question... I didn't say I was going to do it... now, if you wouldn't mind... **** off..
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Old 14th May 2005, 01:03 AM   #18
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and i gave you my answear, and this is what i get?????
gee ask another question it will only get better i guess
cheers
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Old 14th May 2005, 01:05 AM   #19
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Quote:
Originally posted by mastertech
and i gave you my answear, and this is what i get?????
gee ask another question it will only get better i guess
cheers
even if you did give me an answer... you also basically called me an idiot....
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Old 14th May 2005, 02:43 AM   #20
Stocker is offline Stocker  United States
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The answer is you need more than 12V on any transformer you'd care to be carrying around with less than one person, to put out 12V 80A due to the voltage sag with higher current output.

Depending on the power supply section of the car amplifier, you might be just fine with a very low voltage but likely not.

Another route is to scratch-build a supply to suit the amplifier section... that is, bypass the switching supply in the amplifier altogether and make up a 35-0-35 or 70-0-70 or whatever it makes internally to supply the amp.
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