Radio Shack IR detectors

vla7

Does anyone know how to wire a Radio Shack IR detector to a basic stamp?· I have several of the ones from Parallax that I know how to wire.· Those come with three connecting wires·(signal, ground and Vdd).· The ones from Radio Shack come with only two connecting wires.

Mike Green

The two lead devices from RadioShack are phototransistors, not modulated IR detectors. They are not the same!

parsko

Vla7,

I have had success with the IR phototransistors connected to a 555 timer being used as a Schmitt Trigger. It's one extra component, but they are cheap and available from Radio Shack also.

-Parsko

vla7

Oh, ok thanks. I thought it was an emitter detector pair.

parsko

I think they are paired in that the wavelength of light the emitter emits works well with the wavelength of light the detector detects.

The IR detectors have additional circuitry built in that conditions the output signal in accordance with an input. The detectors work well to filter out ambient light effects/noise, such as flourescent (sp?) lights at 60Hz. They also require the emmitter to work at around 38-40kHz square wave.

If all you are doing is detecting a flag (counting revolutions, for instance), then my suggestion should work. You will not need the 38-40kHz square wave on the emitter with this setup (but could, I think, if you want).

What are you doing, btw?

-parsko

vla7

Basically, I am building an IR beacon and need detectors to "see" the infrared signal. I would like the detectors to be able to see the beacon as far back as 30 feet.

Phil Pilgrim (PhiPi)

You will definitely need to used modulated IR for that. The Radio Shack IREDs will work okay, assuming you have a modulated signal to drive them; but the phototransistors will not be adequate, by themselves, to provide a demodulated output.

-Phil