I am trying to make a simple IR detector

Thread Starter


Joined May 18, 2020

Search on "IR reflective sensor" with your favorite distributor. RadioShack used to sell an ancient one. Here is a Digikey search: https://www.digikey.com/products/en/sensors-transducers/optical-sensors-reflective-logic-output/556?utm_adgroup=Sensors & Transducers&utm_source=google&utm_medium=cpc&utm_campaign=Dynamic Search&utm_term=&utm_content=Sensors & Transducers&gclid=EAIaIQobChMI6szQj9_A6QIVUr7ACh0wVgUaEAAYASAAEgJN6PD_BwE.

I show the whole one. Click on Sharp to get a more limited set. Sharp, Sony, Vishay are big names in the field.

I am reluctant to ask where you are, as it doesn't matter to me, but it might make a difference for recommending sources. Are you in the North America or Europe?
Im in Wales, UK


Joined Jan 18, 2008
That's great. You have Farnell/Newark/Element14, right? DigiKey, Mouser, and Arrow are three big American distributors. DigiKey and Mouser are more hobbyist oriented and also export, but shipping can be a killer. Getting common stuff shouldn't be a problem.


Joined Jan 15, 2015
Figures, the Farnell site was down when I tried the link. :( Yes, you could roll your own as you mentioned. The nice thing about an off the shelf solution is the angle work is done and it's all in a nice plastic housing which includes the lens. That's about the only reason I suggested doing it using a one piece reflective sensor. Years ago as a kid I used a pair I made for a science fair project. I just cut a few short pieces of a drinking straw off and put them on my emitter and detector, got my angles for distance and it worked fine. I guess for a few no big deal but if you plan on a few dozen you have your work cut out for you. :)



Joined Apr 11, 2010
I already supplied a link to an IR Reflective Sensor. And it works in N scale without modulation, angling, or anything other than reading the pin connected to the IR sensor with an Arduino. Standalone circuits will work as well, but you have to account for the gaps between rail cars. Easier to do in software.


Joined Jan 18, 2008
Considering all of the IR in our lives, from fluorescent lamps to opening doors, I cannot think of a reliable detector that doesn't rely on source-detector paired modulation for specificity. The "cost" is trivial. A 10F322 is smaller than a grain of rice. That is, if one disregards packaged units. Paper jam/movement detectors for printers and so forth are "all-in-one" devices.