Comparator help

[samarsingla]

Hi
I made a circuit with 393, I have these doubts. First, why is the 10 k resistor there between output and supply. Second, in the circuit I built the output is always coming high. Someone please suggest what could be wrong..
thanx

 

[audioguru]

I made a circuit with 393

Attach the schematic of your circuit for us to see what is wrong.

why is the 10 k resistor there between output and supply?

Look at the datasheet for the LM393 dual comparator. Its output is an open collector so that two outputs or more can be connected together as an OR gate then a resistor pulls them up.

 

[samarsingla]

Hi
Sorry for late reply and bad schematic. Hope it helps..
Thanx

 

[audioguru]

Your sketch doesn't show a connection between the pot at pin 2 and the IC's ground.
What voltage is the battery for the pot?
Your sketch also doesn't show how the photo-diode is connected or how it is powered and if it is connected to the IC's ground.

 

[samarsingla]

Ya all the grounds are properly connected in the circuit. Sorry for the mistakes in schematic.

 

[audioguru]

Are you going to update your sketch showing the grounds, the battery's voltage and how the photo-diode is connected and is powered?

 

[FusionITR]

I dont understand why people don't take a few minutes to make a proper schematic to post instead of using a mspaint picture that no one can read. There are lots of free schematic capture programs out there.

 

[audioguru]

I dont understand why people don't take a few minutes to make a proper schematic to post instead of using a mspaint picture that no one can read. There are lots of free schematic capture programs out there.

I make all my schematics with MS Paint. I just copy and paste most parts from datasheets and other schematics then make straight lines with the Shift key down.
This schematic is made with MS Paint: