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isolated feedback signal - help needed

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darla1

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isolated feedback

dear all

i need help on isolated feedback signal.

for a dc/dc isolated converter need to take output voltage feedback with isolation..i need this isolated voltage same as output.....can any boy tell....how can we do this

thanks
darla
 

isolated feedback

yes there is a chip which does what you want....is it uc1909...no its something like that though....its a kind of 2MHz oscillator which feeds back the actual voltage using Amplitude modulation of the oscillation.

uc3900 ?...no

i cant remeber

but its called an isolated feedback something...


voila...

https://focus.ti.com/lit/ds/symlink/uc2901.pdf

please tell us how it goes...sounds like fun!
 

Re: isolated feedback

hi ee2am thanks for reply

i dont want use ic, i want to use any cmponents,....
 

Re: isolated feedback

use simple LTV817 with resistor limitter for led. (ex: 470k feedback from 300V)
for transistor use 4k7 fixed + trimmer 47k for pull-up to 5V.
 

Re: isolated feedback

hi oscar

thanks for reply and suggestion

can you please give rough schematics of this to get lenear voltge

thanks
darla
 

Re: isolated feedback

Sample for feedback:
 

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    darla1

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Re: isolated feedback

dear Oscar

thank you very much for your post.....

by observing the schematic the output is 4.75 when you give +5.4V and 4.75 becomes 0.15 when u give 100V. I am i right here..

i need the circuit like this

when you give 5v input i need 5v output
when you give 2v input i need 2v output

these things i need with isolation....

thanks
darla
 

Re: isolated feedback

another sample :)
 

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