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Old 3rd January 2007, 10:34 PM   #1201
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Default power supply

I am trying to design the power suply for an Aleph X.Rail voltage is +/-
15 v . From the wiki and other posts a crc pi filter is a good choice.
two caps to ground seperated by a .15 ohm resistor. Is the total capacitance simply the additon of the two caps? and do you usualy use equal values.?


J
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Old 3rd January 2007, 11:06 PM   #1202
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Default Re: power supply

Quote:
Originally posted by tenderland
I am trying to design the power suply for an Aleph X.Rail voltage is +/-
15 v . From the wiki and other posts a crc pi filter is a good choice.
two caps to ground seperated by a .15 ohm resistor. Is the total capacitance simply the additon of the two caps? and do you usualy use equal values.?


J

www.duncanamps.com
download PSUd for free and play with..........
then everything be clearer to you...

btw-answer on all your questions is ~ yes
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Old 3rd January 2007, 11:43 PM   #1203
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The total capacitance depends on your intentions. If you're the advertising department, it all counts, right down to the smallest cap in the front end. In operational terms, I only count the final capacitance after the resistor in terms of a CRC--the R slows the delivery of charge from any capacitance upstream sufficiently that I don't think of it in terms of output to the speaker terminals. Think of it in terms of ESR--with a very heavy R component. Like a poor quality cap.
A matter of perspective: Is the power supply's job to filter out residual ripple and spikes from the transformer and diodes...or is it energy storage for the amplifier circuit?
The answer is yes. And more besides.
If you're looking at it in terms of smooth DC, then the capacitance in front of the resistor is a crucial member of the team. If you're looking at it in terms of energy storage, then the second cap is the star. As a practical matter, anyone building a CRC filter usually buys identical caps, puts a resistor between them, and calls it quits.
The Aleph-X is kind in the sense that its current draw sums nearly to DC. As such, you don't have to get so flustered worrying about the ability to handle peak currents. Give it good quality DC and it will be a happy amp.

Grey
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Old 4th January 2007, 12:13 AM   #1204
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Default Re: power supply

Quote:
Originally posted by tenderland


Is the total capacitance simply the additon of the two caps? and do you usualy use equal values.?

I do the simple addition.

And, I once thought about different values,
expecting maximization of efficient combination of R/C.
That time, Papa and Grey were against my thought.
Everyone usually uses equal values.
I follow the same
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Old 4th January 2007, 12:38 AM   #1205
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Default crc

Thank you for the response and I apologize for the rather basic question. This is my first solid state project and I will do my best researching difficulties on my own.



Jeff
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Old 4th January 2007, 04:50 PM   #1206
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Default Re: crc

Quote:
Originally posted by tenderland
Thank you for the response and I apologize for the rather basic question. This is my first solid state project and I will do my best researching difficulties on my own.



Jeff
you're wellcome to ask questions;
my answer was more related to fact that you'll have more benefit if you learn and know .........as we all do every day

play with psud,and ask if you need to;
in that way you can try various things and see what differences are

happy diy-ing
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Old 5th January 2007, 01:16 AM   #1207
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Default psud

I have installed PSUD and I am having some difficulties.
crc pi filter
source resistance = 20 Ohms(TRANSFORMER)
c= 68000uf *2

I am not sure what to use for the load resistance.

I can calculate a figure for the resistance based on power and current
but it seems low and gives me bad results in psud. Also if I use a resistnace of .25 ohms for the pi filter I get bad data.

I can get resonable results when I use a resistance of .15 and a rather large load resisrance.

Thanks

J -(plugin along)
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Old 5th January 2007, 01:18 AM   #1208
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Source resistance 20 ohms?!
Did you actually measure that on the secondaries? Must be a very small transformer...
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Old 5th January 2007, 01:27 AM   #1209
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Default Re: psud

Quote:
Originally posted by tenderland
I have installed PSUD and I am having some difficulties.
crc pi filter
source resistance = 20 Ohms(TRANSFORMER)
c= 68000uf *2

I am not sure what to use for the load resistance.

I can calculate a figure for the resistance based on power and current
but it seems low and gives me bad results in psud. Also if I use a resistnace of .25 ohms for the pi filter I get bad data.

I can get resonable results when I use a resistance of .15 and a rather large load resisrance.

Thanks

J -(plugin along)
use help for learn how to calculate xformer impedance ;I'll write that here for you,but I always forget that ..and always must look in help,too

use CCL (current sink,current source ,whatever) as load -instead of resistor
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Old 5th January 2007, 01:53 AM   #1210
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Default Re: psud

Quote:
Originally posted by tenderland


crc pi filter

I just choose R
having the value greater than or equal to 10 x 1/(6.28xfxC),
where f= ripple frequency (100 or 120Hz)

Of course, I should remember checking the watage rating of the R
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