• General Module & App Questions
  • How many model trains can I control with one module?

    Each locomotive requires its own module. The module is not just the Bluetooth receiver and transmitter it is also the DC motor and light output controller.

  • Do I have to do anything to link a locomotive to the control app after I have installed it?

    All you have to do is make sure the locomotive is on the track and powered on (making contact with the track and the track is fully powered) - then install and open (first time) or just open (progressive times) the app - it will automatically locate any powered on modules.

  • How do I install a locomotive module?

    Before starting. Please be aware of the following.

    • Familiarize yourself with the installation instructions and your locomotive specifications before starting. Make sure that your locomotive will be able to accommodate the new board.
    • You may require a Phillips or flat head screw driver to open your locomotive.
    • Be careful not to damage your locomotive when disassembling - especially the motor connector wires, if you need to cut them, cut them as close to the existing board as possible. That way you will have more flexibility in attaching the MT module, or later on returning your locomotive to stock condition.
    • Monocacy Trains accepts no liability from any damage resulting from the installation or use of our products.


    1. Open up the locomotive (review locomotive manufacturer instructions)
    2. Identify the motor leads and any LED/light leads (review locomotive manufacturer specifications)
    3. Uncouple the existing control board (may require cutting and stripping motor wires)
    4. Re-attach wires to the appropriate contacts on the Monocacy Trains Board (instructions included with module)
    5. Secure Monocacy Train board
    6. Re-assemble locomotive.
  • How many model trains can I run simultaneously once I have modules installed in them?

    That's easy - as many as you want. Each locomotive is individually addressed and individually controllable. There is effectively no limit to the number you can run simultaneously.

  • Do these modules come with connectors?

    Yes. Every module comes with one wire connector. The connector is designed for wire to wire installation with locomotive wiring. Please refer to the specific module's directions.

  • I am interested in developing my own software to control the MT modules - is this possible?

    Monocacy Trains has created an API for its module control.  You are entitled to download and use our API with the purchase of a module.  Please contact sales@monocacytrains.com and identify yourself as a developer and provide your purchase information.

  • Does the locomotive module also control lights on my train?

    Yes, the Monocacy Trains module can control up to 2 (two) light connections.  Once everything is wired, our mobile app will run you through a small configuration wizard to ask for the number of lights you have connected, which will give you individual and immediately control.

  • If I use the mobile app to control multiple trains, how will I be able to tell them apart?

    Our mobile app includes an "identify" feature that gives you a visual cue to which locomotive you are controlling.  Moreover, the app also allows you to individually name and photo-tag your locomotives for easy identification.

  • Does the module support locomotive sounds?

    Yes, our mobile app allows you to sound a horn or bell and also provides realistic throttle and braking sound effects.  At this time all of the sound comes from the app itself, which is convenient for streaming to Bluetooth speakers.  Imagine your train set in full surround sound!

    The app includes sounds for both diesel and steam engines.

  • Does the app allow me to control multiple locomotives at the same time?

    Yes, our mobile app provides a screen where you get quick access to all of your trains at once.  This is convenient when you have a large setup and want to quickly adjust multiple locomotives.

  • Does your mobile app support Apple and Android?

    Yes, the control app can be run on an iPhone (4s and newer), iPad (3 and newer), iPod Touch (5th gen and newer) and Android phones and tablets that support Bluetooth 4.0 and newer.

  • What model train gauges are supported?

    At this time we have focused most of our testing and support on HO.  However, the module is capable of running N, S and O gauge, given that it fits inside the locomotive enclosure/shell.

  • Can I do more than just turn the lights on and off?

    Our latest update includes support for multiple lighting modes including toggle on/off, flash, pulse/gyrolight and Rule 19 (dim).

  • Does your module only control locomotives?

    Our main focus has been controlling locomotives, however our latest updates include support for 2-position switch/turnout control.  Adding support for switches is as simple as a software update to the app and module.  Please refer to the wiring diagram on our app manual pages.

  • What N scale body styles does your module fit into?

    Our module is small enough that it will fit into some N scale engines.  We specifically tested our module on F7, F7B and FTA/B engine body styles.  If the module doesn't fit into the desired locomotive, there are two alternative approaches:

    1. Install the module into a car immediately behind the engine.
    2. Install the module to control the track power (example)

  • Technical Questions
  • What are the minimum and maximum input voltages?

    The minimum and maximum input voltages are 6V and 20V, respectively.

  • What are acceptable forms of input?

    The Monocacy Trains module supports DC, DCC and AC inputs.  The minimum input voltage is 6V while the maximum is 20V.  Regarding AC inputs, 16 VAC is the current maximum level due to peaks in the AC signal.

  • Does the module support LED and regular bulbs as outputs?

    The Monocacy Trains module supports both LEDs and regular bulbs.  Using LEDs requires a current limiting resistor, e.g. 1K.

  • What is the maximum current rating of the module?

    The Monocacy Trains module is protected by a PTC-type fuse that has a 1.1A hold current. An overload of 2A would take about 20s to trip the fuse. Higher currents will trip faster. The circuitry itself can handle higher than that, the resettable fuse was mainly put in to protect the locomotive motor in case of a fault or an accidental short in the wiring.

  • What is the maximum current rating of the outputs?

    Outputs 1 & 2 provide track voltage with a maximum current rating of 150mA.

  • Does the module need to be on a powered track?

    Yes, once the Monocacy Trains module is installed in the locomotive, it must be placed on a track that is supplying between 6V and 20V. This is required to power the module, however will not do anything with the motor or outputs until instructed from our mobile control app. In other words, your locomotive won't start moving until the app tells it to do so.

  • Can I use a battery for a dead rail installation?

    The preferred way to power our module is through track power, however it can also be powered through a battery (as long as voltage and current requirements are met).  The battery can be wired directly to the red and black wires on our wiring harness. The locomotive power wires that connect to track power can be safely isolated and capped off.

  • Do I need to isolate the motor from the frame?

    Wiring our module is very similar to wiring a DCC decoder.  The motor needs to be isolated from the frame if the frame carries power.  This is very common in older locomotives.  The important thing is that the motor and lights are completely isolated from one another as well as power and ground.

  • How does your switch/turnout drive work?

    The Monocacy Trains module applies input power to the specified "direction" for about 750ms.  In most cases this is enough to switch positions.  We are working on an update that will allow the user to configure how much power, the direction, duration of "on" time and an acceleration.  This should allow the module to support a wider variety of switches/turnouts while also serving as a generic scene motor controller.

  • Warranty and Support
  • Is there a warranty on these modules?

    Yes - There is a limited warranty. The limited warranty is 1 year parts and labor from date of purchase or date of manufacture if date of purchase is not available.

  • What does the warranty cover?

    The warranty covers.
    Replacement or repair of a malfunctioning module in the event of manufacturing defect.

    The warranty does not cover.
    Any damage to the module as a result of installation, mis-use, modification, water damage.

    Monocacy Trains Inc. assumes no liability for any damage or bodily harm to you or your property including your hobby train or set as a result of purchase, installation or use of any Monocacy Train module.

  • How can I get help if my module isn't working as expected?

    For help with a malfunctioning module or for installation questions please contact support [at] monocacytrains.com.  We can also be reached with a message on our Facebook page at https://www.facebook.com/monocacytrains/.


    We typically respond within 1 (one) business day.