Detecting 940nm IR with 930nm phototransistor

Community General Discussions
1

would trying to detect a 940nm IR LED with a 930nm phototransistor be possible?

2

I’m Sure

That’s entirely possible, any drop in efficiency should be negligable. Get the data sheet for the photo trans, it should contain a spectral response curve. This will show the drop in efficiency vs wavelength. I doubt you’ll see much (if any) difference between 930 and 940nm.

3

Vambo is right. From my

Vambo is right. From my experience it would work fine.

4

Ok. what type of circuit do

Ok. what type of circuit do i have to make to be able to detect it with a picaxe?

5

Thanks for the circuit

Thanks for the circuit oddbot, i’m guessing that you power the IR LED just like a normal LED?

6

Yes, although you may be

Yes, although you may be able to feed more current (smaller resistor) to the IR LED compared to a normal LED. 20mA is an extremely common LED forward current rating, but many IR LEDs can take 40mA, 50mA, or even higher currents which will increase the power output.