Slow Motion Switch Machine




This product has been retired.  We no longer have the parts to make more, but if you would like to do so yourself, all the design files can be found on GitHub.

MRServo is a reliable, economical, low-profile switch motor for your layout.

Three Versions for Different Applications

MRServo-1: Basic slow motion turnout drive without auxiliary contacts

MRServo-2: Includes two accessory contacts that switch with turnout position (DPDT)

MRServo-3: Includes one accessory contact (SPDT) and one PowerFrog contact

What's Included

Each kit comes complete with the fully assembled control board, servo, hardware, throw wires, and mounting bracket.

A Crossover Kit allows you to control two turnouts simultaneously using a single control board (-1 and -2 versions only).  This kit includes everything above plus an extra servo, Y-cable, and hardware.

The Control Board Only option is available if you want to provide your own servo and hardware.

The MRServo-1 can be converted into an MRServo-2 or MRServo-3 using the DIY Conversion Kits.  These kits provide the terminal blocks and relay(s) needed for the conversion.  Some soldering required.

Use With DCC Stationary Decoders

With a little extra circuitry, MRServo can be made compatible with most Digital Command Control (DCC) stationary switch machine decoders.  See Driving MRServo from DCC Accessory Decoders.


1.7"(L) x 1.2"(W) x 0.9"(H)

Typical Quiescent Current @ VDD=12V, servo not moving:

14mA (CNTL = GND)
22mA (CNTL = 12V or Floating)


The complete gEDA design files are available on GitHub.

User Manual



Need a slower or longer throw than the conventional MRServo design offers? We are able to customize the MRServo software to some extent and can provide custom-programmed units for a small fee. Email us and let us know your requirements, and we will be in touch about what we can do.

  • $14.00

  • 12 or more $13.00

Available Options

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News & Application Notes

Installing MRServo Above the Layout

While most typical MRServo installations are done beneath the layout, one of our customers had a unique situation where the area under the turnout was obstructed.  Many thanks to Tim Mann for sharing this method and sending us photos of his installation.  Tim’s full set of installation pictures can be found on his Flickr page.


Driving 3-Pin Bicolor LEDs with MRServo

Turnout position indicators on a fascia or control panel can be easily made using 3-pin bi-color (red/green) LEDs.  Fortunately, driving them with MRServo is easy.


3D Printed MRServo Brackets

While I’m still a firm supporter of the tried-and-true industrial foam tape method we’ve sold for MRServo servo switch machine mounting since the beginning, there’s always room for improvement.  Several customers have asked about alternate, mechanical mounting methods, and there’s definitely places that would be useful.  I always have a machine or two that keeps getting knocked loose as I accidentally catch the wire with a tool, or sometimes a spot on the plywood that just refuses to adhere well.

The “conventional” solution would be to have injection molds made, and then have a run of several hundred or thousand parts produced.  This is obviously expensive for us, highly speculative that somebody will actually buy them, and beyond what the meager profit margins on servo switch machines justify.  Fortunately, we live in an absolutely amazing time in terms of manufacturing processes, and nothing is more exciting right now for manufacturing complex plastic parts than 3D printing.

The 3D model of the MRServo-2 / MRServo-3 Bracket
The 3D model of the MRServo-2/-3 Bracket


Using Berrett Hill Touch Toggles with MRServo

One of the most interesting electronic parts to come on the market lately is Berrett Hill’s Touch Toggles.  They’re little electronic switches that operate by the proximity of your finger.  There’s no mechanical movement, so you can put them behind acrylic control panel faceplates and other such and still operate them just by touching the surface.  Unlike a mechanical switch, they never wear out, and they come with built-in indicator lights.Read More...

Simulate a Spring Switch

Spring switches are used by some prototype railroads to save the crew from having to re-align the switch points after passing through the switch.  The switch is sprung in one direction (typically the mainline), allowing any train to pass through the switch from the frog end without manually aligning the points.  When entering the mainline from a siding, this allows the train to continue on its way without having to realign the points to the main – the spring action takes care of this automatically.  Modeling this unique feature can be easily accomplished with an IR sensor and switch machine.Read More...


MRServo is a simple, cost-effective solution for adding remote turnout control to your layout.  While MRServo works in a wide range of turnout control applications, each layout presents its own unique set of circumstances.  Below are answers to some of the most frequently asked questions we have received from modelers using the product.  If you have a question not answered here, please contact us and we would be happy to help.


Building MRServo

Ever wondered how electronic products are manufactured?  In this post, we give you a glimpse into the process we use to manufacture the MRServo slow motion turnout controller.  While the techniques are vastly simplified from that used by high-volume electronics manufacturers, the same basic steps still apply.


MRServo In Action

We always like to see what sort of tips, tricks, and clever uses our customers have come up with for our products.   I thought I’d take a minute to pass along a couple recent uses for MRServo that customers have shared with us.

Using lightweight extruded foam as a layout base has become pretty popular in the last few years.  It’s lighter and significantly cheaper than the traditional 3/4″ plywood, and much easier to sculpt into terrain.  Unfortunately it presents some challenges in mounting switch machines and the like.  Dennis from the UK has worked a clever method of installing the servos through the foam.  It also has the side benefit of being not significantly wider than N scale track, making very tight installations (such as in yard throats) possible.  Take a look at his mounting method on his website.

Moving up to the larger end of the traditional scales, our next clever use is in 3-rail O scale.    Bob Walker started with a Lionel FasTrack manual switch, and connected a a MRServo-2 with a 49MHz RC car radio to make a radio-control version.  The MRServo was customized to have full throw of the servo, rather than our typical throw suitable for the suggested mounting.  It’s connected to the radio’s outputs via another small relay, which provides the input signal for the MRServo board.  Bob sent along a few pictures of the system in action, which I’ve posted as a PDF.  Eventually he’s intending to upgrade the system to Zigbee radios, which should provide the ability to radio-address virtually an infinite number of switches.

If you’ve got something to show off, send us some pictures and a quick write-up at  We always enjoy hearing from our customers, and if you’ve got a good tip, there’s a pretty good chance you’ll be featured in a future blog posting.

MRServo Slow Motion Turnout Control

Ever wanted to automate the turnouts on your layout?  Maybe you have some that are hard to reach?  Or maybe you have a hidden staging yard?  Do you model a modern CTC-controlled subdivision and want to give your dispatcher realistic control over the turnouts?  Or maybe you have a multi-deck layout and other switch machines are too bulky to sit below the upper decks?  No matter what the situation, MRServo is a cost-effective solution!


Installing MRServo Switch Machines

A couple weeks back, I removed the old staging yard from my layout in the process of tearing out the old to make room for my new layout.   I didn’t need it for the new layout, so we decided to repurpose it for writing an article on complex turnout control using MRBus.  It was built ten years ago, long before MRServo was even a thought in my mind, and was consequently powered with a competitor’s large green switch machines.  I’ve gone entirely to MRServos now for the new layout, and we’re obviously going to try to show them off as part of any article we’re working on.

As we were installing them, it occurred to me that it might be nice to show folks how to reliably install MRServo, step by step.  The instruction sheet covers this all, but sometimes a picture really is worth a thousand words.  Once you get the hang of it, it’s quite easy and goes quickly.



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