Note: Updated files for the pin renumbering mod I described in my last post.
This thread is the end result of a discussion about the MTH tach sensor board availability and the fact that it's using an out of production sensor. A universal board was the result that uses a widely available sensor, the QRE1113, and also provides for use in DCS and LocoSound installations. The Gerber files for PCB production are included as well as schematics and drawings of the board design.
By request, here is the shared project on OSHPark, you can order the boards directly here. Currently, six sensor boards will cost you $1.90 shipped. Add the QRE1113 sensor and you have a working replacement tach sensor for your MTH locomotive.
OSHPark Shared Project: MTH QRE1113 Based Tach Sensor Replacement Board
Pads are provided for a 180 ohm resistor for LocoSound applications, however there is a jumper in board copper across the pads for normal DCS applications. If you are replacing a LocoSound sensor, a 180 ohm SMT resistor can be installed after cutting the trace between the resistor pads.
Some MTH locomotive applications require a hole in the PCB for mounting. Since there didn't seem any downside to having the hole always present, that was included in the design.
The astute observer will notice that there are two board images in the design. That was an accommodation for production by the popular PCB prototype site OSHPark, they require at least 1/4 sq/in in a design. At 7mm x 17mm, the board didn't make it. Also, having two board images for one "board" allows you to obtain the boards for a lower cost. A row of holes drilled between the two images facilitates easy separation of the two boards.
There isn't much of a Bill Of Materials for this board, for most applications it's just the QRE1113 sensor and the blank PCB! One note, the QRE1113 version you want is the thru-hole version with the formed leads. This sensor comes in a number of lead configurations, so obviously you want the proper one for this application.
This is the lead configuration of the sensor required for this application.
However, they also come in a couple of incompatible configurations, just be careful when you're ordering your QRE1113 sensors.
