I am in the process of installing IR object sensors on my railroad. I just started back in this hobby and am a little bit old (80) which gives me a problem with fine motor control. This makes soldering a definite challenge. I am using a small IR collision detection device that runs at 3.3 volts and interfaces with an Arduino. There are several you tube videos on this subject I can add something new. My track (Kato N-scale Unitrack) is already down. The baseboard is 3/4" plywood. I have modified the sensors as follows: 1) De-soldered and removed the existing 5 mm IR receiver and emitter 2) I added in the place of the IR devices two 2-pin header connectors. * 3) I bought new IR emitters and receivers in 3 mm size. ** 4) I soldered them to 2-wire header leads that mate with the connectors I placed on the board * * The header wires and their board connectors come in a package of 20 for $8.39 from Amazon (SING F LTD 2 Pin 2.0mm PH Micro Electrical JST Plug Flame Retardant Cable Socket 20 Pcs 12cm Battery Connector Plug with Wire Cable ** The emitter and receiver are available on eBay and amazon. I bought them from Amazon (New 80pcs 3mm 5mm 940nm Receiver/Infrared LED Emitting Diode IR 20 pieces of each type and size) 3mm size are what I used for N scale. To attach the IR devices to the wires I used an interesting little piece of shrink tubing containing a solder ring. It is about 1" long, sized for 24-26 gauge wire. You put the two wires (in this case 1 wire and one component lead) and heat it with a heat gun The solder melts joining the wires and the tubing shrinks making a nice insulated joint. I bought them at Amazon: ( 100PCS Solder Seal Wire Connectors by Haisstronica Heat Shrink Solder Connectors White 26-24 $13.99) I have used the solder shrink tubing quite a bit now. It works so well when I need to join/splice wires. I believe it comes in various sizes for different wire gauges. The 3 mm devices fit very nicely in a 1/8 " hole drilled through the track base. I then drilled a larger whole from the other side of the baseboard so I could push the device up and set it even with the track. I drop of clear Gorilla glue holds it very nicely. The sensor board I attached to the underside of the baseboard with two sided foam tape. There is a hole for a small screw. The sensor board runs very nicely at 3.3 volts. I use a 25 pin D connector and cable to bring the sensors from the layout to the control panel Arduino mega board. Hope this helps someone.