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Say John 42 [message #9767]

Fri, 11 August 2006 17:58

Manualblock
Messages: 4973
Registered: May 2009

Illuminati (13th Degree)

Anynews on the transformer modeling experiment? How do you get the sec resistance figure?

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Re: Say John 42 [message #9770 is a reply to message #9767]

Wed, 16 August 2006 23:54

Forty2wo
Messages: 163
Registered: May 2009

Master

Hi M, I am on a big project for work.
I did model a very low DCR transformer I had on hand. I used the tool in PSU2. And direct measurements. Came out to 11.8 ohms. And falls into the don’t want to drop on my foot category This with the set value filter I proposed, I don’t have it here, 10U-10h-50U maybe? Fed this into a stepped load, 100ma-150ma. And there was a fair amount of ringing.

Increasing the R value of the transformer would reduce the ringing. So that is good right…

Looking a bit deeper, if you reduce the trans+filter to a basic LCR circuit. You have a tank circuit with a certain ‘Q’, if you increases the resistive component, be it higher trans resistance, choke resistance, or whatever . you reduce the Q and the ringing . So is this the way to go? I don’t think so, it smacks of one dimensional design.

More on this later. I did not want to leave you hanging but I am just too busy to do more right now

Try picting a low R transformer and change the filter for best result…John

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Re: Say John 42 [message #9772 is a reply to message #9770]

Thu, 17 August 2006 08:04

Manualblock
Messages: 4973
Registered: May 2009

Illuminati (13th Degree)

Thanks John; thats plenty. I also found Duncanamps Forum for PSUD users so that is helping me.

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PS options [message #9789 is a reply to message #9770]

Fri, 18 August 2006 21:24

PakProtector
Messages: 935
Registered: May 2009

Illuminati (2nd Degree)

Hey_Hey!!!,
Another option would be to go CLCLC and drop the inductance of the 'L' stages. Say to 2 Hy each, experiment with capacitance values and see where the final ripple comes equal or perhaps just less than a single stage goes.

Keep in mind that it is not likely that the 'shape' of the resulting ripple voltage is also going to be different with a multi-stage filter compared to a single.

It is my opinion that keeping the DCR low is a good idea. It isn't possible to do it 'all else kept the same' so it shouldn't follow that PS performance is tied to a the value of a single parameter. Either way, examine the performance of the filter as component values change around a reasonable centre, or preliminary value.
cheers,
Douglas

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