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Old 1st November 2007, 09:05 PM   #1
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Default PSUD2 help needed

right so im designing a power supply in psud2 but dont know what value the transformer impedance. i know what transformer it is but i cant find out the figure.

i have not built an amplifier before so its mostly new, what sort of figure is usual for the transformer impedance .

i have tried a number of figures from 50ohms to 150ohms and get about 20 volts difference in output between the two.


sorry just looked a bit closer in psud2 and the figure says source resistance ,,, how do i work out this?

cheers
soundbadger
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Old 2nd November 2007, 03:19 AM   #2
Sheldon is offline Sheldon  United States
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If you are going to ask for help (same question in multiple threads, no less), at least pretend to put some effort to read the answers people give you: http://www.diyaudio.com/forums/showt...16#post1339116

If it wasn't clear from the previous reply, look at the dialog box you get after clicking on the transformer icon, you'll see that the "source resistance" box has a button to the right labeled "Ohms".

Sheldon
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Old 2nd November 2007, 04:06 AM   #3
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Soundbadger,

When you click the trafo icon in PSUDII, next to "offload" voltage, there's a button which takes you into a calculator. Enter the trafo offload voltage and the current specs for the trafo (e.g. for a fullwave rectifier using a Hammond 275-0-275 @ 50mA, simply enter 275V for the voltage and 0.05 for the current. I use 10% for regulation. The calculator then calculates the offload voltage and resistance.

I am not sure how accurate this is, but when I model B+ voltage, I get to within 5V of my empirical values, which at around 350VDC is more than close enough.

NOTE: if you're going to use a bridge rectifier, then for a 275-0-275, you'd enter 550V into the calculator.

I hope this helps and I understand the angst when learning and creating your own PSU. Run your own models, post the schematics and give the specs for your PSU parts, and myself, or someone else will no doubt run it in PSUDII and can check your PSU. Of course, I have to run PSUDII at work as I only have a Mac at home.

People on this forum are extremely helpful and knowledgeable, although it certainly looks better if you attempt your own answer. It reminds me of an experience in France when I was a lot younger. People were not pleased that I expected assistance when I asked for things in English. As soon as I began using my best French (which is quite atrocious even after getting my CSE French) I got loads of help and folk actually found my pronounciation understandable in spite of my thick Lancashire accent.

Hope this helps, and post your PSUDII results when you get some!

Charlie
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Old 2nd November 2007, 05:27 AM   #4
Sheldon is offline Sheldon  United States
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Quote:
Originally posted by cbutterworth
it certainly looks better if you attempt your own answer.
Charlie, I'm not taking Soundbagger to task for not attempting to find the answer. That's what this forum is for. Nor it an issue of knowledge, as I have found sincere people of all levels respected here. S asked how to calculate the source impedance and got at two valid suggestions. Apparently not finding either expanation adequate, S simply reposted virtually the same question in a new thread. If the responses to the original question weren't clear or not understood, then ask for further clarification - no problem. But to simply ignore attempts to help and repost the same question is bad manners.


Sheldon
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Old 2nd November 2007, 04:11 PM   #5
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Sheldon,

My posting was not intended as an admonishment to you for your reply to Soundbadger. I really hope you didn't take it that way, if you did, then I am sincerely sorry, especially as you're one of the folk who responds to my persistent whining over my Aikido.

Charlie
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Old 2nd November 2007, 04:27 PM   #6
Sheldon is offline Sheldon  United States
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No worries Charlie. I just wanted to be clear on what my objection was. I don't want to discourage Soundbadger from asking any question, just be considerate of the time people take to reply. Common courtesy, nothing more.

Sheldon
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