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Old 18th September 2009, 03:00 PM   #4891
sekess is offline sekess  United States
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Hi metalman,

Forgive my typo - I meant to write 20000uF and 68000uF. That was my error.

My question however was twofold:

1. At what capacitance should we be looking to add thermistors on the secondaries.

and

2. What cold resistance value thermistors would we put on the secondary side? Would we use the same 10 ohm thermistors that we are using on the primaries? Or, another value?

Thanks again,
Steve
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Old 18th September 2009, 03:08 PM   #4892
sekess is offline sekess  United States
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Hey Uriah,

What your saying could be true. I don't know myself. I was referencing post 3008.

I too have no turn on thumps etc. I was more concerned with extending the life of the caps and rctifiers.

Thanks,
Steve
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Old 18th September 2009, 03:15 PM   #4893
AndrewT is offline AndrewT  Scotland
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Hi,
from the mains:- it's peak drive voltage divided by acceptable peak current.
From the secondary:- again it's peak drive voltage divided by acceptable peak current.
It is very unlikely when one enters those numbers into the two equations that one will arrive at the same resistance for both sides of the transformer.

Isn't it so much quicker to type 20mF rather than 20000uF or 12pF rather than 0.0000000012uF? oops should that be 0.000012uF?
One does not have to go back and check that the correct number of zeros have been entered.Same when we come to read the posted value.
I hate having to count all the leading zeros and following zeros when the metric system has made it so easy to avoid those kind of typing and reading errors.
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Last edited by AndrewT; 18th September 2009 at 03:19 PM.
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Old 18th September 2009, 03:23 PM   #4894
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Quote:
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Isn't it so much quicker to type 20mF rather than 20000uF or 12pF rather than 0.0000000012uF? oops should that be 0.000012uF?
One does not have to go back and check that the correct number of zeros have been entered.Same when we come to read the posted value.
I hate having to count all the leading zeros and following zeros when the metric system has made it so easy to avoid those kind of typing and reading errors.
Couldn't agree more!
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Old 18th September 2009, 03:24 PM   #4895
sekess is offline sekess  United States
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Hey Andrew,

Ok, so typically what's an acceptable peak current on the secondary?

Thanks,
Steve
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Old 18th September 2009, 03:27 PM   #4896
AndrewT is offline AndrewT  Scotland
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peak charging current vs repetiton rate will be known to the manufacturer.
Each cap value and each manufacturer and cap temperature vs acceptable life will require a different limiting peak current.
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Old 18th September 2009, 03:39 PM   #4897
sekess is offline sekess  United States
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Ok,

Thanks Andrew,
Steve
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Old 18th September 2009, 04:11 PM   #4898
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Maybe you guys could study the powersupply schematics of some of Papa's earlier work.

Example :
I'm working on an Aleph1.0 version with a cascoded JFET input stage and an output stage with 50 Hitachi TO3s per channel.
(since none of you guys seemed to want some of them i volunteered for a few hundred of the 2SK135, all-same batch number in a box => http://www.diyaudio.com/forums/showp...3&postcount=25 )

The Push-Pull capable Aleph1 draws 500W/ch idle from 67V rails, the powersupply of the amp also merely has 2 thermistors on the primaries.
The capacitors in the Aleph1 size a total of 100KuF per channel.
These hold nearly 8 times as much energy at 67V than your F5 capacitors at 24V.
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Old 18th September 2009, 06:59 PM   #4899
Zen Mod is offline Zen Mod  Serbia
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Maybe you guys ......
I luv ya , big Dutchie Whale .
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Old 18th September 2009, 07:03 PM   #4900
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