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Old 1st September 2008, 01:29 PM   #1
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Default Help for choke input regulated PSU

HI , ( sorry for my english)

Suppose I have a linestage 6922 wit 200 Volt series regulated (
with a mosfet type). The storage cap is about 1000mF. End.
Now I want modding into a LC input type (after the regulator).
Does I have to erase the cap and soubstitute wit L?
perdone for my horrible exposition, I am totally rookie on electronic

Paolo
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Old 1st September 2008, 04:24 PM   #2
DougL is offline DougL  United States
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Download Duncan Amps PSUD

Some basics: The voltage after the first choke / Cap will be about .9 of the Transformer. Cap input PS give about 1.4 times the Transformer.

It is also important to get the Q of the Choke input less than 1. About .5 is optimum R = (1/Q) * Sqr(L/C) this equation calculates the required resistance of the choke. You can add an additional resistor.

Also, you need to insure that the choke meets min and max current for correct operation. While PSUD is probably definitive, here are the equations.

Imin = Vrms / L
Imax = Idc + Iac where Iac = 1350/L for 60 Hz and about 1100/L for 50 hz

You may need a higher voltage transformer.

Doug
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Old 1st September 2008, 04:35 PM   #3
Sheldon is offline Sheldon  United States
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A picture is worth a thousand words. Show us a schematic of the power supply. What do you hope to gain by making the proposed changes?

Until then, I don't see the purpose of placing a choke after a regulator.

Sheldon
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Old 1st September 2008, 05:19 PM   #4
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Thanks guys,

Doug, time to study your formulas

Sheldon,

because I like the Thoersten Loesch approch. I think you all know him.
The toccata MK1 preamplifier has a PSU that have intrigued me.
I think To skip the first choke and rest is quite similar to my "idea".
The regulator is approx. the same .
I'm perplexed by the low value of the choke. Only 10H. But for this
maybe I can ask the author.

Thanks for your comment

Cheers,

Paolo
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Old 1st September 2008, 06:45 PM   #5
DougL is offline DougL  United States
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Quote:
I'm perplexed by the low value of the choke. Only 10H.
Do yourself a favor. Ask PSUD first. Thoersten Loesch has stopped posting on the hobbyist sites, because of very understandable professional commitments. Ask here first.
Quote:
I think To skip the first choke and rest is quite similar to my "idea".
In order to communicate better, a rough drawing of your idea would be very helpful. Also a link to the schematic of the " toccata MK1 preamplifier" would be helpful.

My advice is to either understand before you build, or build per the schematic, then modify.

Doug
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Old 1st September 2008, 07:05 PM   #6
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Doug You are right, my mistake.
Unfortunately electronic is sort of chinese language for me
below is the schematic of the Toccata mk1
Link

thanks

Paolo
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