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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.


MTH QRE1113 Tach Sensor Board


Last edited by gunrunnerjohn
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@rtr12 posted:

Just added this one to the OGR projects list. Let me know if you see anything I should add or change (link in sig below). Another fine project for the forum members! And thanks again for all you do for us around here, much appreciated!

Looks good to me.

@Jim Sandman posted:

GunRunnerJohn - Does this sensor board also work for Proto 3, or just Proto 2?  It seems to imply Proto 2 for sure with the mention of the LocoSound.

True PS/3 tach boards are a totally different design both electrically and physically, they're not compatible with this board.  However, the PS32 Stacker board actually uses the PS/2 style sensor board and would work with this board.

@Dave Zucal posted:

John, the QRE1113 contains an LED. Is the resistor needed to limit current to the LED for LocoSound, and if so, why doesn't the LED need current protection for the PS2 application?

The PS/2 boards include current limiting for the LED in the QRE1113, the LocoSound boards obviously do not, hence the resistor for those.  Note that for LocoSound replacements, you may not need the resistor on the board as it's frequently included in the wiring harness.

First practical application of the tach sensor board.  Since I would have had to remove the sensor from the MTH board for this custom install, I figured this would be a good time to test my sensor board.

Another good reason was the fact that the sensors on the MTH boards don't have leads long enough for this tiny flywheel on a Williams brass K4, so I couldn't use it anyway.


Images (2)
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@Lou1985 posted:

Does it work just like the factory tach sensor/board?

As I expected, it works just like the factory tach sensor, no problems at all.  A nice trick to have in the stable.  For installations like this Williams K-4, it was a whole lot easier to use this than to try to fit the stock tach sensor board since I don't have any of the sensor chips with long leads.

Last edited by gunrunnerjohn

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