Near IR detection

Jondice

980 nanometers doesn't seem too far away from 940 nanometers, which is what I need to detect. However, the IR detector (www.parallax.com/detail.asp?product_id=350-00014) seems to filter this out ... any way I could get it to work, or does anyone else know of an easy way to detect 940 nm?

I could use a QTI sensor, unfortunately, I'm already using 5 of them and I don't have much room for where I need to place this one. I could run some fiber optic line from the place I need to detect over to the QTI Sensor I suppose (assuming I could find some fiber optic wire in short order, and assuming it will transmit 940 nm radiation).

Thanks for the help!

JED1

Sorry, I know of no way to get the two different frequency of devices to work and if they did their sensitivity would be very low.
If you look at the manifactures specifications for these devices they are very narrow band by design.
You are best to get devices that matches each other. I have had lots of luck getting these from Digi Key or Jameco. Several other electronic supplier should work as well. Most will sell them in single quanities and should cost around $3.00. You will also need to pay attention to the modulation freq. as
well as they use PLL's to filter out other frequences to increase your noise immunity.


The fiber optic direction seems more involved and possibly more expensive from my experince unless you have something in your junk box you can use.

Good luck

allanlane5

The part number you called out is an IR-Decoder. This is an active device, which expects its input signal to be 38 Khz modulated IR. That means it wants to see an IR-LED flashing at a 38 Khz rate -- and only then will the device's output go low. It will stay low as long as it sees the flashing. This signal is typical of home electronics remotes.

It sounds like you want an IR-Transistor -- a transistor whose 'base' leg actually recieves IR light. That's the 980 nanoMeter or 940 nanoMeter signal you are referring to.

Now, if you could oscillate your 940 nMeter signal at a 38 Khz rate, the device you called out should detect it.