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is 7815 regulator ic is damaged?? it gives output voltage at 12v, 6v input

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mobinmk

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Hi frndz,

Am new bie here.

i make an regulator voltage supply using 7815 ic.
components
230/16v stepdown transformer.
full bridge rectifer - 1n4007

then 100uf capacitor for filtering
output voltage is 21.23v
output of 7815 ic is 15.6v
output of 7815 ic is connected across Vout and com

100uf capacitor.

1n4007 diode is reverse bias across vin and vout of 7815 ic

this is my design.

nw i connect230/ 6 - 0 -6 stepdwn transfmr, replace 230/16v.

i connect the full bridge ckt across 6-0 of trnsmr

output voltage of 7815 ic is 5v.

then
i connect the full bridge across 6-6 trnsfmr
output voltage of 7815 is 11v

is 781 ic damage ??


pls help me ...


regardz

mobin
 

A 7815 needs a minimum input of 17.5V to work properly. With less input voltage then it does not work correctly. Yours has an input voltage that is too low when it does not work correctly.
 
A linear regulator requires a Vi-Vo > 0 if you want it to regulate.

you are using a Vi = 6V or Vi = 12, which is less than the required voltage to regulate a fixed 15V output.

here is an app note on the basics of linear and switching regulators.


If you look in the following datasheet for a Fairchild 7815 you'll see a Vdrop specification. That value should be exceeded (i.e. Vi-Vo > Vdrop) if you want the device to regulate it's output.

Don't have any idea if what you did would damage the part. I'm not even sure how you hooked up the circuit as you didn't supply a schematic (a description makes a poor schematic)
 
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