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help regarding comparators.

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tehmaas hasan

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greetings every one.

I have made a comparator using UA741 OPAMP IC.

PROBLEM: WHEN i power the ic the by providing 5volt to 7th pin and gnd to 4th pin. it shows output on led in other words the led glows. i dont know why it is giving the output voltage?
It must show output when I play with the non-inverting and inverting pins of the IC. but without working on these pins it glows the led.
why is it so?

if it is offset voltage then why it is providing too much offset voltage since led glows on 2v.

kindly help me as soon as possible.
 

Dear tehmaas
Hi
Can you show me what kind of circuit you have used ? didn't you use any resistor as pull down ? if you post your schematic i can help you .
Best Wishes
Goldsmith
 

A 741 cannot operate down to zero volts input with a single power supply voltage. Also it likely will not operate at only 5V total supply voltage.

Use an LM339 or similar instead. It's designed to operate as a comparator from a single supply voltage as low as 2V.
 

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