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tl431 and optocoupler feedback for sg35252

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babatundeawe

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can someone help me fine tune this circuit for feedback/error correction for sg3525 pushpulll configuration. i need to get the values of the resistor right. i dont want to use a transformer in between just want to sense the voltage directly.

thanks
 

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  • feedback.rar
    13.3 KB · Views: 214

I can help but I could not open the file you posted
I extracted your file. is it a Tinycad file?
 

thanks picgak,

just downloaded it now and it did open. u can use proteus to open it.

i hav converted it to pdf

thanks
 

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  • feedback.pdf
    23.5 KB · Views: 234

I have opened your circuit and made a slight change in it (see fig) so what is your required voltage at the output point which I marked as V
 

thanks

ok i want to use this as a feedback mechanism for sg3525 pwm inverter. so i wish to measure the output voltage directly (230v)

thanks for your help
 

use 56k for R2 and 2.2k variable as Rv1 give 2.5v as ref to pin2 of sg3525
 

i want to use this as a feedback mechanism for sg3525 pwm inverter. so i wish to measure the output voltage directly (230v)
TL431
Vka - 37V (MAX)
In this scheme, it will burn.
 

TL431.png

+V1 <= Vka_max(37V)
 

@pplus

can u tell what u mean by Vka? is the cathode voltage of tl431 or that of the optocoupler?

thanks
 

it means maximum voltage the TL431 can withstand is 37v
so +V1 marked in above circuit should not be above 37V
 

ok guys i think ihave to order for another one cos i guess this one i have appears to be damaged due to high voltage.
 

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