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!
What is MRServo?
MRServo-1 Control Board
MRServo is a low-cost, low-profile, slow motion model railroad switch machine using small and inexpensive RC servos to control the turnouts on your layout. Three options are available to suit almost any situation. The first, MRServo-1, is the simplest and least expensive. It does its job of controlling the turnout, and does it well, without any bells or whistles. MRServo-2 and MRServo-3 provide extra features in the form of accessory contacts. With two sets of accessory contacts (DPDT form), the MRServo-2 is well suited for simple power routing and integration with signal systems and control panel indicators. MRServo-3 provides a single set of accessory contacts in addition to a set of PowerFrog contacts which intelligently route power to solid frog turnouts. PowerFrog eliminates the need for special current limiting circuitry or frog “juicers” in these situations.
As with all Iowa Scaled Engineering products, MRServo is guaranteed for life. And for you adventurous modelers, it is an open-source / open-hardware product. Full schematics, design files, and source code are available on the product documentation pages. We encourage you to build your own, improve upon it and, if you so choose, submit your ideas back to us so everyone can benefit.
PowerFrog Technology
MRServo-3 Control Board
Available exclusively on the MRServo-3, PowerFrog technology provides a reliable, short-proof way to route power to solid frog turnouts. (Examples: handlaid, Peco Electrofrog™, Shinohara™, and Walthers™ models.) These turnouts will create a short if the points make contact with the opposing rail before the contacts driving the frog switch polarity. Traditionally, the solutions have included additional gaps in the point rails to isolate the frog, various current limiting devices, or active frog “juicers”. With PowerFrog, this is no longer necessary. When MRServo starts to throw the points, it momentarily isolates the frog. Once the servo completes throwing the points, it sets the direction relay to the correct polarity and, after a small delay, re-energizes the frog.
Putting this intelligence in the switch machine has many benefits. First of all, it works with any control system: DCC (any make), pre-DCC command control, traditional DC, 3-rail, etc. Secondly, since the switch machine already knows the position of the turnout, you no longer have to create an intentional short-circuit to signal the frog “juicer” to change the polarity. Third, the overall cost can be significantly less. So, protect your wallet and your investment in turnouts and use MRServo as your switch machine of choice!
Installation
Installation of MRServo is straightforward, but please be sure to follow the directions. After you have installed a few, the process goes very quickly. A tutorial on our recommended installation procedure can be found here.
As mentioned above, MRServo is ideal for space-constrained applications such as multi-deck layouts. Both the control board and the servo itself are small, resulting in a very low-profile installation.
Frequently Asked Questions
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: 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.
