Examples of voltage doubling circuits in amps?

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chris_d
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Post by chris_d »

Looking for some "real world" usages of voltage doubling power supply circuits. I don't really know much about this type of circuit at all, though i have heard it mentioned many times, i haven't had any reason to look into them until recently.

For instance like so:

http://hyperphysics.phy-astr.gsu.edu/hb ... ldoub.html

B+ coming out the top of the schematic, and the bottom grounded, i suppose?

What kind of capacitor types/values would this entail? Does the schematic require anything else to work in a preamp circuit?

My application would be for a 2x 12ax7 preamp. Trying to get 130vac into more like 250vdc.

Any input welcome.

-chris

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Ronsonic
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Post by Ronsonic »

I don't have any good examples for you, but a couple of references you might try:

Scratch around and see if you can find an ARRL Amateur Radio Handbook. They do an excellent explanation of this type circuit.

Also, the Duncan Power Supply Designer, which you can download here http://www.duncanamps.com/psud2/index.html will model it for you.

HTH
Ron
My Pedals, Products, Services and DIY Blog: http://ronbalesfx.blogspot.com/

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soulsonic
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Post by soulsonic »

I believe the "standard" old 100 watt Marshall power supply is a full-wave voltage doubler. The old Orange schematics show a similar thing as well.
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chris_d
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Post by chris_d »

soulsonic wrote:I believe the "standard" old 100 watt Marshall power supply is a full-wave voltage doubler. The old Orange schematics show a similar thing as well.
Ah, I hadn't thought to look at either of those. They both do something similar, though a bit of a different setup from the example circuits i have seen.

Also, someone on another forum pointed me towards the Fender 400PS bass amp that has another twist on it.

I read some more and now i basically figure that i need as big caps as i can fit in there, to counteract some of the side effects of the doubling circuit. I don't understand exactly how the center tap versions ala Marshall and Orange work, but they seem to be using 100uf caps in there. It looks to me like the 400PS uses 630uf caps for its circuit...

Well it looks like something to start with anyhow. Thanks guys! I am off to try to make sense of the Marshall/Orange way now.

-chris

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Post by Kaos »

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chris_d
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Post by chris_d »

Kaos wrote:
Ronsonic wrote:ARRL Amateur Radio Handbook
1936 Edition:
http://www.pmillett.com/Books/arrl_1936.pdf

1941 Edition:
http://www.pmillett.com/Books/arrl_1941.pdf

from this site
http://www.pmillett.com/technical_books_online.htm
That's funny. I went to that website just now, and realized that i have been there before and that i had already downloaded the files in question. There they are sitting in my "to read" folder with too many others!

-chris

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tubetek
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Post by tubetek »

Howdy All...first post.
One of my favorite examples of the doubler setup (and one I own) is the UNIVOX 1061 bass amp from 1970-71 era. Go to http://www.univox.org and in the schematic section you'll find the 1061 schematic with component/transformer values. Hope this helps...
Tom

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