MP5 Review and Digitrax DS64 Integration

Model Railway Control Systems Control Systems ("MRCS") is the main dealer for these wonderful little motors that originate in the Czech Republic where they are made by MTB-Model who appear to be a prolific Model Railway manufacturer in HO, TT and N scales.  Both websites provide all the necessary MP5 dimensional data.  Suffice to say the MP5 presents a very attractive footprint in all dimensions.  This topic is about my experience with the MP5.

Seth Neumann from MRCS has been very helpful throughout this process.  He has a very cool business catering to all sorts of  wonderful open source model railway focused electronics, including the MP1 and MP5 switch motors.  He indicated that he has sold thousands of them and they have been very reliable.  He also mentioned that he has hooked up an Arduino to create an “IKEA Style” repetitive testing machine and put them through 50,000 cycles so far with no ill effects.  That’s a lot of railroading!

As mentioned in my Bedside and Hinged Blog, errant blankets are forever attacking the venerable Tortoise switch machines I have installed thus far.  I was looking for a "drop in” replacement solution for the Tortoise which I have already hooked up to Digitrax DS64 DCC Turnout controllers for throttle switch control, as well as panel mounted push-button switches and LED turnout direction indicator lights.  I really did not want to undo everything I had implemented and start over.  Tortoises are wonderful, but are an accident waiting to happen on my B&H and I am also contemplating some small shelf layouts at home so wanting something much less tall

The MP5 features two SPST internal switches, (the MP1 has only one); one of the reasons I chose the MP5 so it would offer identical features to the Tortoise, namely circuits to drive indicator lights and frog power.

First Impressions

I opened these up and had a good look.  Seth only had 4 in stock the day I ordered, so that what was in the box.  Well, minus the Tortoise, Lol.  I put that in there for an early comparative picture.

Much smaller and no sharp edges either!

I had a refresher read through the supplied installation documentation which is also available on MRCS' website.  I'll just provide the link for the MP5 page where there are links for each of these documents:

• Brochure
• Installation Instructions
• Mounting Template
• Wiring and Control Application Notes
  • This is an excellent document produced by MRCS rather than the manufacturer.  It is constantly evolving as more users document their experiences.  A combination of this document and the installation instructions helped me get my test circuit built and working.

Initial Testing

I did just enough reading to dial in a light 9 Volts and 300 mA on my bench power supply to give one of these a first whirl. I generally start at a lower voltage than called for just to see how things work.

• I popped off the pushblock connector and used some tiny alligator probes to go right to the pins.
• Ground to COM and a +lead to poz1 and away it went, moving quite a distance very quietly.
• +lead to poz2 and away it went the other way.
• Working up to specified voltage increased speed a bit, but not noise.

Adjusting the Servo Throw

These units are fully adjustable and the travel can be set to any of 3mm, 6mm, 9mm, or 12 mm throw distances.  The throw rod wire supplied is heavy and stiff, so as mentioned in the documentation (and advised by Seth) smaller, springier wire will allow use of a wider travel and keep your points sprung firmly against your stock rails.  

Adjusting the throw requires turning the unit over (a must do so everything doesn't fall out) unscrewing the base of the unit (two self tapping screws) and sliding out the yellow end plate.  I doubt I'll need the horn type arms for turnouts, but one can see where they would be handy in a lot of applications and open up a whole world of possibilities for using the MP5 for animation. 

• Digressing moment- It is highly likely that if Emma the Stegosaurus finds a role on the B&H, she will have a turning head and variable color eyes depending on the direction she is looking!  The MP5 will enable such things!  Imagine what John Allen would have done if he’d had access to devices like this?  These might even fit in a cab to enable directional engineers!

Lifting off the base revels the inner workings.  What a brilliant little design!  

Adjusting the throw is done on the end of the gear that is revealed with the sliding plate (piece on right of above image) is removed.  You can just see the pin on the end of the gear above.  This diagram from the MP5 Installation Instructions explains the travel adjustment.  [Update: On the B&H, I am using wire of the same diameter as supplied , but longer to pass through my layout substrata, and the 9mm setting.]


 

Caution

• Those inclined to bugger with stuff and then wish they hadn't because they aren't particularly good at re-assembly should skip ahead to where it says SKIP TO HERE!
  • Seth mentioned that none of this matters to users of the devices.  He's right.  Unless they're engineers!  Then it’s critical!
• The motor runs in one direction and the single shaft on the main gear has several cams that engage wee micro-switches on the circuit board where there are many electronic components.  Depending on the current direction, the engage and shutoff switches swap roles!  Must be some logic control in that circuit board!
• The thing self-calibrates due to the cams!
• I'm guessing the board is mainly diodes and a speed controller, because, unrestrained, the tiny little motor spins at a good clip.
  • I can imagine that shaving off one or more of the cams will provide a controllable device that just spins!  Apart from their intended use, the MP5 and MP1 provide a cheap source for some nice gears and a tiny but torquey little motor!
     
• The gear shaft is held in place by the base which also holds the circuit board and micro switches right where they belong. 
  • If you want to run the MP5 with the lid (base) off, you'll have to hold the shaft in position, and may have to hold the circuit board as well.
• It all goes back together easily.
• You don’t need to take it apart, but if you decide to disassemble the yellow slider, Be careful with the screws and nuts.  A single turn to loosen will make them adjustable.  These parts are stainless and if you launch them, they aren't magnetic, just in case you think your hyper-handy extendible magnetic parts retriever is going to help you!

SKIP TO HERE: Ok, unskilled tinkerers can start reading again.

• Adjusting the throw is very well covered in the instructions.  You'll need small pliers with grooves to pull and reinsert the spacing plug.  I only adjusted one so far, so some of my pictures may show the default 6mm travel still implemented.
• If you launch the plug into space, there are spares in the box!
  • If you launch them all into space, I'll bet a piece of plastic rod of the right diameter can be used as a substitute.
• Seth mentioned that the 3mm travel spot is recommended for HO. 
  • I had to try 12mm to watch the travel and that is a healthy displacement.  I think my stream table can be powered by the MP5!
  • Once done tinkering, I set it to 3mm travel and put it back together.
• Commercial Break:
  • You really want to go read my Blog to fully understand my intense desire to tinker, the stream table, what bedsheets have to do with Tortoises, why anyone would have a hinge in a river, and find out why a Stegosaurus named Emma is relevant to the MP5.
    End of Commercial Break     

Wiring the MP5 to the Digitrax DS64 Quad Stationary Decoder

As of last night, there was no specific approach for the MP5 with the Digitrax DS64 With this topic, now there is!  

• Given that the MP1 and MP5 appear to be very similar devices, I elected to try the circuit for the MP1 and the DS64 in the Wiring and Application Notes first.
• DO NOT use this circuit with the MP5. 
  • While it works with the older MP1 it does not work with the MP5 and got the DS64 so hot on one corner I could barely hold it!  I was rather shocked.  Well, more burnt than shocked, but amazed that it didn't work.  The circuitry inside the MP1 must be much different. 
     
• BUT reading more of the Application Notes found me in a section about the Digitrax DS52 (Zephyr). That plus a circuit on the Installation Notes caused an ah-ah moment and when I went to bed I tinkered some more.   The beauty of having your train layout as part of your bed ... if you can't sleep, you railroad!
  • By 3 AM I had everything working, including my Fascia controls and the right readings on my meter coming off the internal SPST led me to believe the LEDs would be OK as well.
  • Today, the LEDs were also wired up - SUCCESS. 
    • Everything is perfect.
    • ​​​I even left the Tortoise on the same DS64. Totally interoperable.
• The diagram in the installation notes is a bit confusing with poz1 and poz2 being shown on the power side of the circuit when they are also labelled on the MP5.  
  • Just ignore those words and know that those two wires are actually coming from your DS64 outputs (1R, 1G, etc.)

Without further adieu, here is what you have all been waiting for, the MP5/DS64 circuit and some key notes about it:

• The only thing needed to control an MP5 with a DS64 are the red wire from COM to 1G (or 1R) and the black Jumper and wire from MB2 to 1R (or 1G)
   
• The LED circuit has it's own power supply and the current direction is switched by the AUX1 portion of the MP5.
   
• The push-button switch is only connected to the DS64 and has nothing to do with the MP5. 
  • It is an alternative way of triggering a turnout if you happen to be standing in front of it and would rather use a push-button on the facia rather than your Digitrax throttle. 
  • Of course, when the button triggers the DS64, the MP5 then gets triggered by the DS64.

Below, the circuit as-built at my end using a standardized 8 port Terminal Block (TB) setup.  I use TB's for everything as they aid in tracing problems and help keep wires routed properly and neat and organized.  

• Important Notes:
  • Shown below, note the small black jumper wire implemented across the MB2a and MB2b ports (pins 10 and 12, bottom row on the push lock).  The black wire will be coming from a Digitrax output port (1R or 1G, 2R or 2G, 3R or 3G, or 4R or 4G) and I just popped it in the same hole as the jumper.

Close-up of Jumper Wire Implementation

• Wired as shown, the MP5 is a drop-in substitute for a Tortoise with the DS64.
  • Therefore you need to make sure your DS64 is in Stall Motor mode (CV01 set to Closed) as described in the Digitrax  Manual for the DS64. (Even though the MP5 is not a stall motor, it works like one as far as the DS64 is concerned)
• Unplug the DS64 from Loconet and remove the power source whenever tinkering or you might bugger it!  the Digitrax forum is full of such errors!
• I recommend using solid rather than stranded wire
  • The push block is awesome but requires a fair bit of force and trying to juggle it while making sure you don't have errant strands of stranded wire may cause you to accidentally put a wee screwdriver through your finger!
  • Make sure you pay special attention to the labelling on the MP5 - it's easy to accidentally run wires to the wrong row on the push block.
    • I should imagine that if space constraints present, the push lock can be omitted and wires soldered directly to the pins on the MP5.  The whole plug-pin assembly could likely even be sawed shorter. 
  • I'd recommend doing the wiring with the push block joined with the MP5, or label the top side of the push lock with a sharpie or something.  It will only plug in one way, but it is hard to tell which side is which when it’s unplugged.
  • I'm using 26 gauge solid wire.  If I'd been thinking better, I would have bought a lot more colours of wire before I started this layout and then things would be much easier to trace.
• This application is mine, for my panel, adjustments may need to be made for yours!

Th circuit as shown works perfectly.  The MP5's get their power from the DS64 outputs.  I’ve run two simultaneously so far with no degradation.  The turnout control pushbuttons are connected to the DS64 inputs, and the LEDs are powered by a separate power supply ( Digitrax PS14 in my case).

• The turnouts can be switched with the switch control on any Digitrax throttle via Loconet.
• The turnouts can be toggled between routes with the facia push buttons.
• The panel LEDs glow green when the switch is (using Digitrax jargon) closed (straight) and red when thrown (diverge).

A few photos below of my temporary testing set up.  I'll update the thread once these are properly mounted and the wires routed properly.  At this point I was working on confirming things and making sure the MP5s could co-exist with Tortoises.  They are compatible.

Below are some photos of an MP5 wired up to the DS64 and my panel. You can see how the slider has moved (6mm default) along with the change in colour of the LED.

• On the B&H, each MP5 gets it's own terminal block ("TB")  and all wiring having anything to do with that MP5 will go through that TB.  I will eventually label everything on the layout with a label maker. 
• Two other terminal blocks gang power and ground from a Digitrax PS14 power supply to power to the LEDs. 
  • The common lead off all LEDs converge on a common TB which goes to -ve on the PS14
  • The positive lead off the power supply goes to a ganged TB and from there to the (in my case) AUX1 common of every MP5 pushblock.
  • The SPST contacts in the MP5 feed directional current to the LED (with resistor in series) on the panel associated with that MP5 and Turnout.  I am using 3 lead, bi-color LEDs, so when the internal MP5 SPST switches contacts, current is reversed and the LEDs toggle between red and green, just like they did with the Tortoise.
    • I had two MP5s and one Tortoise running off the same DS64 for a few hours. 
      No issues whatsoever.  
    • I have since removed the Tortoise from the circuit so it may not look to be hooked up in the photos.  Will move it someplace less prone to a blanket snag until I can get some more MP5s.

This is my setup for one MP5 showing the ganged 12V power supply going to the Aux1 central contact.  The gang ground for the LEDs is underneath, out of sight. 

Conclusion

The MP5 is an excellent little device.  Very thin and therefore perfect for upper decks on shelf layouts where clearance is always an issue. 

• Wired up as shown, they can be a direct plug n play swap for a Tortoise with a DS64 Quad Stationary decoder.
• They seem to be compatible with a great many things and MRCS has their own line of stationary decoders (MPD8) as well.  I will try these in the future.
• At less than $20 U.S. the MP5s are a bargain.  Even cheaper in cases of 30!  
   

Below, what comes with each MP5:

So tiny compared to the Tortoise.  Note, 2 MP5’s are shown below, side and top view.

In my view, well made, a needed item for model railroaders, and great value for money, backed up by a great dealer. 

MP1 & MP5 to DCC

First od all, I'm located in Czech Republic. Then I have relatively good knowledge about MP1, MP5 (and rest of MP.s that are not that popular - see photos). In rest of text I'm calling them MP1, but meaning is all MP1, MP5, MP6, MP7 etc.

Long time ago a created snap in DCC decoder for MP1 http://www.fucik.name/masinky/MP1/ (working on MP5 as well but MP1 is cheaper :o) )

That is very good and very comfortable/easy to install. Little disadvantage is, that you have to install one decoder to one MP1 and it increase price a little. Then I did version for eight of MP1s. http://www.fucik.name/masinky/MP1/8xMP1.php This one is more "price friendly", but "wiring unfriendly".

Little trick of MP1 (not seen with MP5 yet) is, that MTB changed form during a time. Original MP1 was extremely reliable, infallible. but new model is little cheaper and less reliable. You can recognize by number of screws on bottom. It exist three and two screw versions (small screws on bottom of motor that holding case together).

Thank you

Thank you Mike,

Its a little hard to follow the wires in the photo. From what I understand,

you left the jumper (M2a M2b) installed. 
connected the DS64 1R to the MP5 M2a terminal and the DS64 1G to MP5 COM terminal
and routed the the switch to the DS64 COM and S1?

Thanks again

Greg

I have upgraded the schematic to something more readable, but yes, you have it right.  

There is no jumper installed with the MP5, you need to implement one.  I just used a short length of black wire.  Likely should have used a longer one in the photo to better illustrate.  There is now a better picture of the jumper wire as well.  

Otherwise correct and by switch I am using momentary contact push buttons, off-on-off configuration.

MP Motor switch machine controller

Jindra:

could you contact me off line, you're website is pretty cryptic about contacting you, if you don't live in Prague.  I'm the owner of MRCS and I am interested in your MP Motor switch machine controller.

sales@modelrailroadcontrolsystems.com

Seth

MP5 Review

Mike:

very impressive, especially operating in parallel with a tortoise!  3 small points not covered in the review:

1) while the MTB documentation states a range of 8-16V, we've had reports of  stalling at voltages below 12V, so if you think you are going to have marginal voltage, check operation carefully and be prepared to increase the supply voltage.  Also, use 0.039 or even 0.047 music wire for the actuator, as noted above: this makes the installation a little less fiddly and provides positive point pressure.

2) while the motors are very similar to those found in SG90 servos, they are not "servos."  We also offer servo controllers, but those are for analog servos such as found in RC vehicles.

3) while the MP5 motors can be used as a drop in replacement for a Tortoise in the example above, it is NOT a stall motor.  It requires ~ 125mA of current during travel (2-3 seconds) and then shuts off, drawing no current.  A tortoise draws about 20mA all the time.  So while the MP uses less power overall, many commercial switch decoder/controllers can not supply enough current to operate them.  See "Wiring and Application Control Note" http://www.modelrailroadcontrolsystems.com/content/MP%20Motor%20Wiring%20Application%20Note.pdf

for more details.

Seth Neumann

Model Railroad Control Systems

MP5 Review

Mike:

very impressive, especially operating in parallel with a tortoise!  3 small points not covered in the review:

1) while the MTB documentation states a range of 8-16V, we've had reports of  stalling at voltages below 12V, so if you think you are going to have marginal voltage, check operation carefully and be prepared to increase the supply voltage.  Also, use 0.039 or even 0.047 music wire for the actuator, as noted above: this makes the installation a little less fiddly and provides positive point pressure.

2) while the motors are very similar to those found in SG90 servos, they are not "servos."  We also offer servo controllers, but those are for analog servos such as found in RC vehicles.

3) while the MP5 motors can be used as a drop in replacement for a Tortoise in the example above, it is NOT a stall motor.  It requires ~ 125mA of current during travel (2-3 seconds) and then shuts off, drawing no current.  A tortoise draws about 20mA all the time.  So while the MP uses less power overall, many commercial switch decoder/controllers can not supply enough current to operate them.  See "Wiring and Application Control Note" http://www.modelrailroadcontrolsystems.com/content/MP%20Motor%20Wiring%20Application%20Note.pdf

for more details.

 

Seth Neumann

Model Railroad Control Systems

 

Agreed. That for lever throws and omega loops in linear  throws are always worth while.

Andy

Andre:

 You can't use a series bi-color 2-lead LED with MP motors for two reasons:

1) The bi-color 2 lead LED trick relies on continuous current through the stall motor (while it's in the "stalled" condition) to light. MP motors in contrast ONLY draw current while they are moving, then no current, so the LED will go dark as soon the motor has finished its movement.

2) Most LEDs can only handle about 30mA, above that they burn out. MP motors draw about 150 mA while moving, so there is a very good chance you would destroy the LED and it would fail open and the motor wouldn't work at all. Of course the LED ***might *** not have time to overheat during the 2 seconds the motor is moving, but it would shut off  in any case when the motor reached the end of travel. Eventually you would kill the LED (see above).

A better circuit is to use a 3 lead common anode bi-color LED and use the MP motor in 3 wire mode. You'd put the common anode in series with a 1K resistor to the (+) COM lead of the MP and the Red and Green leads to poz1 and poz2 (M1,M2 on MP4 and MP10) respectively (reverse them if you want the other color in that position).

 

This is why I emphasize that MP Motors are NOT stall motors in the quick start guide: https://www.modelrailroadcontrolsystems.com/content/MP%20Quick%20Start%20Guide.pdf

 

Seth Neumann

Model Railroad Control Systems

In general if you are using an MP5/MP5/MP10 the switch machine has DPDT contacts, so assuming you are using the first contact for frog switching, you'd use the second for LEDs, this is clean (no chance of a power cross with something else) and isolated so as Mike states the voltage can be whatever you like. For MP1s or the rare application where you need both a direction indicator AND a separate isolated contact, the 3 Lead common anode LED is a good choice.

 

User Ed Maskell found this diagram, it's in Czech but I think it is pretty clear. I'll do this up in English with a few options in the next version of the MP1 Wiring and Control Application Note  https://www.modelrailroadcontrolsystems.com/content/MP%20Motor%20Wiring%20Application%20Note.pdf

 

I use the aux ports on the MPs to switch bi-color aleds per my circuit early in the thread, but I am using a separate power circuit for them