Posted by Damir [ 213.202.85.64 ] on July 28, 2006 at 18:05:39:
In Reply to: Re: PS Transformers posted by manualblock on July 28, 2006 at 17:12:41:
"I have a couple PT's on hand; but not the ability to test each one for it's parameters."
What you need more? You can measure primary and secondary DCR, and with formula Rt = Rs +(Ns/Np)^2 * Rp you can find the "equivalent" PT resistance, where Rs is a DCR from CT to the one end of the secondary (from 0-350V).
For example - you measured Rp=5 Ohms, Rs=20 Ohms. Then you can measure unloaded sec. voltage, say 350-0-350 V.
Ns/Np is PT turns ratio, equal to voltage ratio (sec/prim.), say 350/117 = 3. Then our Rt = 20 + 3^2 * 5 = 65 Ohms. This Rt rectifier tube on the secondary "sees". If you don`t know current rating of your PT, then you can guess by its size, and if it is salvaged from some equipment (preamp/power amp).
You now have all you need for PSUDII - Rt, Utr - choose your rectifier and a first filter (LC or CLC), put the CCS as a load (estimated current of your amp) - and start playing with the program with various values, rectifiers, etc.
For example, you need 375V/100mA DC and you tried 10µ/10H-100R/100µ with 5R4GYB rectifier you have in your junkbox...yes, that`s about it!
Breadbording proves that you are quite close, and you liked the sound - happy end... 
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