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.

Q: Can you change the throw angle of the servo?
A: Yes.  The default is ~30 degrees, but custom angles can be programmed for a nominal fee.  Keep in mind that our recommended installation method relies on the spring tension of the wire to hold the points in place, so having extra throw is beneficial.

Q: Why can’t I adjust the throw angle like in some other competitor products?
A: For the purposes of driving turnouts, the 30 degree default throw angle of MRServo is sufficient and provides useful spring tension on the switch points.  In the interest of keeping costs low, we don’t believe it makes sense to put the adjustment capability in each and every controller (and for you to pay for it) when you are likely to use that feature at most once in the lifetime of the product.

Q: Can a single control board drive multiple servos, such as in a crossover configuration?
A: Absolutely!  The MRServo-1 and MRServo-2 can each be ordered with the crossover option which provides an additional servo and a Y-cable.  The MRServo-3, however, while able to drive multiple servos, requires an individual control board for each side of the crossover if you want to take advantage of the PowerFrog feature (since each frog is on a different rail).

Q: Is double-sided tape a reliable mounting method?
A: We provide a strip of heavy-duty double-sided tape to mount the servo and the control board to the layout.  As explained in the installation instructions, be sure to clean the thin layer of grease off the case of the servo before mounting.  That, combined with the heavy-duty tape, should provide trouble free operation.

Q: Do you offer 2-channel (or 4, 6, 8, etc) control boards?
A: At this point, no.  Except for special circumstances such as yard leads with a large number of co-located turnouts, a single channel control board located next to the turnout makes most sense given the typical distance between turnouts.  Even in the case of a yard lead or industrial setting, the small size of MRServo allows it to be easily mounted in the available space.

Q: What type of switch is needed to control MRServo?
A: Any SPST or SPDT switch can be used.  The control input (CNTL) needs to be grounded (GND) to select one turnout direction and left floating (or tied to VDD) to select the other turnout direction.

Q: Can I use a pushbutton to toggle the turnout position?
A: Yes.  A special option is available that allows the turnout position to toggle each time the pushbutton is pressed.  Contact us for details.

Q: Can MRServo be controlled by a DCC system?
A: MRServo cannot be directly addressed by a DCC system, but is compatible with a variety of DCC accessory decoders.  Installation instructions can be found here.

Q: Can I power MRServo from the DC output terminals of power pack?
A: When powering MRServo, be sure to provide a clean DC voltage between 8V and 16V.  We have found that some power packs do not provide a smooth voltage on their DC outputs.  Consequently, they have some pretty ugly power that can cause MRServo to glitch.  It won’t hurt anything, but the switch machine won’t function correctly either.  If you have problems, you may need to put a 100uF 35V electrolytic capacitor across the output terminals of the power pack.

Q: I like your product, but wish it did XYZ…  Can you do that?
A: Maybe…?  Just ask and we will see if we can tailor the product to fit your needs.  If it results in a substantially new or improved product, you might even get a free one to test and evaluate.  We are always looking for feedback, so please let us know.



  1. You state that SPST switch are ok to use, but what about DPDT on/off switches? And if they can be used what would be the correct wiring for them?

  2. DPDT are fine. Just use one pole. Connect the middle contact to the MRServo CTRL input and either of the other contacts (but only one) to GND.

    1. Does that go for DPDT on/on switches as well? I am just getting around to installing my MRServos on my layout. Could you provide me a schematic on how they should be wired?


    1. As Michael mentioned, to use a single DPDT switch to control it, you just use one half of one side, as if it were an SPST and wire it as shown in the manual. I’ve included a sketch for clarity below. This will work like a normal control panel switch – one direction of the electrical switch will always throw the track switch in a particular direction.

      For two DPDT solution, there’s no way to do it where putting either toggle in a given position will always give you the same track position. However, if the desire is just to have control from two locations and you can see the switch points, you can wire a pair of DPDT switches (or SPDT switches) together so that either control will reverse the track from its current position.

      Here’s a quick doodle of how to connect both scenarios.

  3. How do I wire the aux contacts from j5 to a led lighting control panel? (red/green leds)

    Thanks Dennis

    1. I’ve uploaded a quick sketch to show how to do this:
      LED Turnout Indicator sketch

      This will work with separate LEDs for main and diverging routes. It will also work for combined red/green LEDs with three legs, though you may have to switch positive and negative connections depending on whether they’re wired for common anode or cathode.

      It won’t work for 2-leaded red/green combined LEDs. Those will either need both J4 and J5, or you can do clever tricks using AC power and diodes. Either way, it’s tougher, but can be done if you already have 2-leaded red/green LEDs installed. Let me know and I’ll point out some ideas.

      That said, I see you ordered a MRServo-3, which has the Powerfrog feature on J5. You’ll probably want to use J4, which is a normal set of accessory contacts. Otherwise, your lights will turn off while the turnout is in motion (unless, of course, that’s what you want).

  4. I see you created a way to use your product with the Touch Toggles and wondered if it would be possible to do something similar with the ESELCO Fascia Mounted Turnout controller

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