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…..........--- Small 1206 SMD Sensors for Cheap IR Sensor Modules ---

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I was interested in using some of the cheap IR Sensor Modules for places on the layout where I'd like to use very small sensors on opposite sides of the track. It isn't too hard to solder to 1206 SMD devices so searched for 1206 Emitters and Sensors that might work with the IR Sensor module after the larger emitter and sensor were cut off the module. This would also make it easy to mount the module out of sight and mount the small sensors in a scenery feature. The following is what resulted. Ask questions if it isn't clear.

I ordered the emitters and the sensors from DigiKey as they are cheap at about 50 cents each and freight is inexpensive from them and the order arrives fairly quickly. I also put part numbers above that you could try from other sources. They seem similar to what I got but I did not order any of those so you are on your own if you go that route..

The IR control modules (above) are inexpensive at 10 for $9.00 on Amazon. Remove the old emitter & sensor and solder the new ones on. Use the offset green squares on the SMD's to see which end the wires solder to. They need to be in the order shown.

Soldering to the 1206 SMD's is pretty easy if you have something to hold them. I got some flat ended alligator clips and soldered them to some welding rod. This come in handy also on decoder installs and other projects. The wire is ESU decoder wire that I believe is 36 gauge. My Klein wire strippers strip it in the 32 gauge notch.

Tin the wire.... tin the 1206 SMD ends ..... put a drop of solder on the iron tip ..... hold the wire to the SMD end.... touch it with the iron tip .... soldering is done.

One could run the wires off in a different direction also.

I was seeing that the emitter and sensor could be placed 5 to 6 inches apart. I forgot to see how sensitivity could be changed by adjusting the pot on the control module. With the emitter and sensor opposite each other the reflectivity of the object being sensed (black to white) doesn't matter. The object only has to break the beam between them.

Once the beam has broken the sensor the red LED turns on. The output from the sensor module could be used in different ways to activate other functions.

I tried the emitter and sensor facing the same way as they are on the stock IR sensor module. Like this the distance they worked at was greatly reduced and the reflectivity of the object passing by effected the distance also. A black surface was very hard to read. Hear again I forgot to try adjusting the pot on the control module.

The emitter and sensor can also go under the track as shown above. With the ME code 55 track they fit between the ties but the wire and the SDM's seemed to lift the track a few thousands of an inch so one might have to clearance under them just a bit. For some reason they didn't work side by side but as shown they worked. Might of been able to move them a tie apart but didn't try that.

Follow the wiring diagram and get the wires soldered to the right ends of the SMD's and the posts on the control module. I messed up first time and it didn't work but nothing was damaged and once I reversed them all was good.

I used a simple breadboard setup to test and might be a good idea to test with it before putting everything on the layout. 5v positive & negative goes to the two right posts on the control module. The left post is connected to the anode side of the led. Then a 1.5K (or other) current restricting resistor goes between the cathode side of the LED and 5v negative. Place the emitter and sensor facing each other or facing the same way and test. Use something white at first at least if they are facing the same way.

Parts for this are very inexpensive at less than $3.00 for a sensor module, emitter and sensor.

Hope this helps someone.

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