Need help with lab. SMPS

hi everybody
i am trying to design 0-100v 0-25a SMPS
problem are that i can't find schematics
can i use
NCP1034 and/or L4981
http://www.onsemi.com/PowerSolutions....do?id=NCP1034
http://www.st.com/internet/analog/product/63215.jsp
please help me
won't be bad if it's low noise,ripple and high regulation
i have
LX1664 and lm21212
http://www2.microsemi.com/datasheets/lx1664.pdf
http://www.ti.com/lit/ds/symlink/lm21212-1.pdf

Hi My friend
Where is your problem ? add a simple op amp in your feedback path and then give it's out put to the opto coupler ( it's LED ) via a resistor , and then take a feedback from out put and compare it with a reference voltage . if you change it your voltage can change from 2.5 up your desired value . but if you want zero volt , you can use some diodes in series together after your filter .
Best Wishes
Goldsmith

Huge thanks!

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but how to fix the problem with the noise and ripple

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View attachment 100v_25a.gif
this is a 0-100v 0-25a SMPS but some compnents can't be seen
any idea what they could be

Hi again

but how to fix the problem with the noise and ripple

Click to expand...

A proper filter at your out put ! . for example a differential filter in your out put to achieve pretty high powers without any noise and ripple !
Why that way ? try to use a simple UC3845 or TL494 , which is pretty simpler . at first read their datasheetas and application notes .
Best Wishes
Goldsmith

what about ncp1382
it's low noise,soft switch..
it has everithing

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http://www.onsemi.com/PowerSolutions/product.do?id=NCP1382
i think it's perfect

any schematics of differential filters?
also how to shield the transformer

Hi again
Differential filter ? surely ! if you wind two inductor on a core and use two or maybe three capacitor ( like EMI filter ) it will be a differential filter ( differentiating magnetize flux ) .
And about shielding your transformer , there are many ways ! such as copper screen method and ground ! it depends on your applications ! for example in a high voltage system such as 30KV shielding is a bit complicated ! with resin and coper screen ! but in your applications i don't think it would be pretty important !
Good luck
Goldsmith

Hello GOLDSMITH i want the steps for repairing of faulty pc smps; the smps fan is rotates for a while when shorted its green and black pins on 20 pin connector . PLEASE PROVIDE ME STEPS FOR TROUBLESHOOT THE PROBLEM. thanks in advance.

https://www.repairfaq.org/sam/smpsfaq.htm

everything
from vcr to pc powr supplies

Hi Peter
The presented link by author of this thread will be good for start ! an advise when you want repair a system : at first you should know all thing about it's topology . it means you should know theory of operation , at first . thus you can find the problem , simply and then repair it . however it is impossible that i try to repair something like a PC power ! because it is pretty compact design and it is a bit time consuming ! hence most of the time i'm preferring to be a designer instead of a repair man . unless there will be a high power system . then it has enough worth to pay attention and consuming time . ( for example at powers more than 5 KW it will be agreeable to consume the time ! ) it is my opinion . and it is possible that you be disagree with me . but don't forget that two things are pretty important for a human with limited time of living in this world !
1- Time
2- Price

Best Wishes and good luck :wink:
Goldsmith

to be esier:
first track the collector of the transistor to find out is it forward,flyback ...
then the emiter to find the ground
then the base to find the drive

i have repaired many SMPSs whis way


also for low noise and high power,high eff. what topology should i use flyback or forward