i have a optical ir detector that puts out .5vdc when ir is shined in its general direction. i would like to shade it from indirect light and have it register by beeping a small speaker when high ir is detected.
can i detect .5vdc with the arduino
i don't know what the exact detector is. i can tell you that it is in a to-46 metal can package and that it looks like an optical detector. i do know that it is for infrared/light detection.
i have hooked it to a multimeter and i have determined that in minimal indirect light the output is roughly .040vdc and when ir is directed at the detector the voltage jumps to .5vdc.
Is the detector a two terminal device or more terminals? Either way an Arduino analog input pin can read any positive DC voltage in the range of 0-5vdc, with around a 5mv step size resolution, so .5 volts would result in around a 102 count value from the A/D conversion.
Lefty
You probably need to add a pull up resistor, then you will get more of a change between light and dark.
left,
the detector is 2 terminal. when i do the adc it is awful jumpy with the numbers, is this were the pull-up resistor would come into play? what size would you suggest?
is this were the pull-up resistor would come into play? what size would you suggest?
I would like to see a datasheet for your IR detector before I could recommend anything, does the device have a part number?
Lefty
what size would you suggest?
Taking a flyer at this I would say 100K. It can't do any harm.
no datasheet, salvaged part off of some old night vision. i looked for a datasheet but couldn't find one.
the number on the detector is 2386 k31. here is a small picture of the part.
http://picasaweb.google.com/lh/photo/-kz2fEX39AwddSgsDFUKUA?feat=directlink
So just try 100K and go from there. Bigger resistor the more voltage swing you get but the higher impedance it is and the nosier it gets.