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@Darrell posted:

Since the app pairs with the loco's, I believe you can pair different loco's to different devices so you can have 3 different loco's controlled by 3 different throttles (devices). You can not have 1 loco controlled by multiple devices.

Correct Darrell.  If you had an operating session with friends, each could have a device and control a loco or locos.

In addition one person with one device can control many (I think 99?) Locos.  But only 4 separate throttles will show on the screen at once.  You would have to swipe to see the next 4.

Android must be around the corner.  I was contacted about beta testing.


Interesting question. I opened the Blunami app on an iPhone and an iPad and then switched on two Blunami2200 installed engines. The two Blunamis connected only with the iPad in multi-engine mode.. When I switched off the iPad and left the iPhone app up, both Blunamis then connected to the iPhone, again in multi engine mode. It appears that only one device can be used even with multiple Blunamis. I would like to know what others are finding.

I have a bunch of Proto-1 locomotives that could benefit from this option. I was thinking, though, that the 2-amp converter could be used if the motors were connected in series. Dan Dawdy was using 2-amp DCC decoders on his RS1's with series-connected motors with great success. The one thing to watch out for is wheel-slip (acts like a one-legged differential in a car).

During further study, found that the procedure for connecting more than one device app to different Blunamis is critical. Bring up only one device app and then turn on Blunami #1. Then bring up the second device app and turn on Blunami #2. Both will connect to their respective devices in standard mode which will result in individual control of each Blunami via the separate devices, the desired result. Again, both apps up initially will not work.

Here's my initial report on the Blu Shark project, conversion of a 1990s 3-rail AC Weaver/Samhongsa Sharknose diesel to 3-rail Blunami control and sound.

The dual can motors, when wired in parallel, had a stall current exceeding the rating of my power supply, 10A.  Wired in series, the stall current was 4A at 18V, at the Blunami 4408 board's specified current limit.

With the motors wired in series, connected directly to the track pickups, and run with 18VDC power on the tracks, the Weaver Shark achieved a speed that's respectable for a freight hauler that ran mostly on secondary lines, probably around 45 smph, hauling 15 average freight cars (scale).  Observed current reached a maximum of approximately 1A when hauling that train up a 3% grade.  This corresponds to a load resistance of approximately 18 Ohms.

My layout is powered by 3 Lionel Powerhouse 180 "bricks", whose nominal AC output voltage is 18.9V without load.  Loaded track voltage stays near 18V throughout the dual-track mainline.  When the Powerhouse feeds a full-wave bridge rectifier and a 20 Ohm resistive load, a filter capacitor of approximately 1000µF is needed across the rectifier input to keep the ripple minimum voltage above 18VDC.

The Shark was experimentally wired with the bridge AC terminals attached to the (replaced) pickup rollers and chassis common, the aforementioned capacitor across the bridge DC leads, and the latter connected to the Blunami board DC input terminals.  The Blunami motor output was connected to the two can motors in series.  Its sound output was connected to the Shark's original fuel tank speaker (it was delivered with a QSI electronic horn).  The Blunami board DC input voltage at idle was 24.5V, with virtually no ripple, below its 26V rating.  Under load, the DC voltage does drop somewhat and there's some 120 Hz ripple, but the peak ripple voltage does not exceed 24.5 V.

In this temporary configuration, the Blunami control board and Blurail software worked flawlessly.  Operation was smooth and minimal loss of speed occurred when pulling 15 cars up the 3% grade at roughly 40 smph.  Some tweaking of the throttle response characteristic appears necessary, but that will await further refinement of the conversion.  No 120Hz hum was heard out of the loco's speaker.  Whether running at speed or creeping along, the Shark pulled smoothly.

Next up will be permanently mounting the components and adding a DC>DC buck converter regulator.  I've done some work on the test bench with that, but have yet to install it in the Shark and actually run a train.  The bench tests were encouraging.  Once the fundamental motor control is optimized, lights and couplers can be addressed.  I'll also do a complete write-up of the project, including extensive measured data for motors and rectifier, scope waveform photos, and so forth.

My tentative conclusion is that the Blunami control board is a very practical alternative to DCS and TMCC for dual can motored diesels in general freight or yard service.  The tradeoff is between absolute speed and meeting the Soundtraxx 4A stall current limit, so it may not be appropriate for mainline varnish and hotshot freights.  And there's no way to meet the stall current limit in steamers with large can motors.  Once the Blu Shark is finished, an Atlas switcher and possibly a Weaver E8 may be up next on the workbench.

Last edited by KarlDL

A hearty welcome to the Blunami operators club. It's good to hear of others confirming my good operating experience with Blunami. I've done Blunami with AC track power, DC track power and battery and all worked well. The Blunami4408 with the 4A stall current does help a lot with larger engines. I am currently working on an approach to operating electro-couplers using an FX . Those CV shortcuts built into the app are really helpful.

@KarlDL posted:

And there's no way to meet the stall current limit in steamers with large can motors.  Once the Blu Shark is finished, an Atlas switcher and possibly a Weaver E8 may be up next on the workbench.

I am running a large Pittman 15v 9433 motor in an MTH scale Hudson. Stall current is about 5 amps. Pulling 8 freight cars, longest on my test track, with smoke running it only draws 1.2 amps max. I agree you wouldn’t want to use this with a Mabuchi 550 or 555 motor found on many Williams brass and Weaver engines but Pittmans are much more efficient.

I chose to rely the Blunami’s protective circuitry if stall current is exceeded but fast fuses or PTCs could also be used if stall current is a concern.


Hey Pete!  If you substitute a 24V Pittman motor in that Hudson, you'll still have a top speed north of 60 scale mph (ask me how I know this!)  And if you also get rid of the rubber tires, I'm willing to bet that you'll keep the stall well under 4 amps.  I'll mail a crisp $5 bill to the first one who fills his traction tire grooves with JB Weld!  ;-D

@Ted S posted:

Hey Pete!  If you substitute a 24V Pittman motor in that Hudson, you'll still have a top speed north of 60 scale mph (ask me how I know this!)  And if you also get rid of the rubber tires, I'm willing to bet that you'll keep the stall well under 4 amps.  I'll mail a crisp $5 bill to the first one who fills his traction tire grooves with JB Weld!  ;-D

You guys worry too much. No worries here. Soundtraxx did their homework. No way to pull 15 21” cars without traction tires.


Ride Fast, Take Chances

Pete, I'm taking a cautious approach because of the newness of the Blunami cards and the conservative nature that was instilled in me in engineering school 50 years ago.  I suspect that 95+% of the time, the 4408 card will perform just fine in many engines, regardless of stall current.  Unfortunately, both of my steamers with can motors and "conventional" control have Mabuchi motors, so they'll get ERR Cruise Commander conversions.

I looked up the spec sheet for one of the more popular Pittman motors a few weeks ago and found that its rated stall current was nearly 15A, which surprised me, given discussions on this forum.  One must consider not only the average current seen on meters but also the peak current that has the potential to activate the card's protective features.  PWM is used in many motor controllers (including Blunami) and the peak current during a low-duty-cycle pulse will be far greater than the average.  I'll admit to not having looked into that in any depth.  But I do know that my DC power supply often went into current limiting when the Shark's motors were wired in parallel and the current limit was set to 2A, while the supply's display never showed more than 1.4A.  This was worsened by the faulty pickup rollers (later replaced) causing intermittent losses of supply voltage and therefore current surges upon restoration of conductivity.  In that circumstance, the Shark did not operate smoothly nor reliably.

I did run the Shark with the motors wired in parallel, with pure DC power, and the Blunami card in-circuit.  Replacing the faulty pickup rollers resolved the reliability issues.  Displayed currents reached well into the 1-2A range at speed.  The linearity of the Bluerail speed control left lots to be desired, but it wasn't tuned to the engine at the time.  It appeared that parallel motors was a practical possibility, as long as a DC>DC buck converter board was used for regulation and I was willing to accept the (unlikely) risk of a stall.  In the end, the series connection gave me all the speed and pulling power I desired along with better control linearity, compliance with the Soundtraxx specification, and the option of not including a buck regulator.  I might make different choices on a different loco.

As long as we acknowledge that risks exist when operating outside the manufacturer specifications, let's all pursue what we're comfortable with and share our results.

I just viewed your site, that's some great work Darrell!  In your case you had no choice, but I don't own a lathe, and I'm not crazy about pulling and pressing the wheels just to smooth out the tread.  What are the chances of scraping off the excess JB Weld with an xacto blade before it sets hard by running the loco upside-down in a cradle at very slow speed?  Or perhaps, by allowing the wheels / axles to spin freely in the chassis, and smoothing the tread with a grinding bit in a rotary tool?

How does the hardness of metal epoxy compare to that of the railhead, and of the factory tires?  If I could get it close, do you think the tread would eventually wear perfectly smooth from operation?  It's appalling that we have to resort to any of these techniques.  Thanks for sharing!

I found the JB Weld difficult to work into the grooves and then shape flush, but you are probably more skilled than I am. It was very easy to shave flush with lathe tooling, so manual cutting/filing may work out for you.

If you try the JB Weld, I urge you to test the product on some sort of "sacrificial" sample beforehand to "get the feel" of its working time and how it responds to tooling and filing. That way, you can try out your shaping ideas.

I don't have enough running time to say what the wear properties are, but I hope this steel-impregnated epoxy is slightly flexible and "grippy."

Good luck!

Blu Shark Part II:

My previous post on the Blu Shark project described operation with a bare-bones AC to DC converter: a simple full-wave bridge rectifier with smoothing/filter capacitor ahead of the Blunami card, with the Weaver/Samhongsa Baldwin Sharknose diesel's twin can motors wired in series.  I continued onward to a more sophisticated conversion scheme, using a DC>DC buck converter board following the rectifier & filter to produce a regulated DC input to the Blunami card.

Here's a picture of the Nude Shark, stripped of its original QSI DCRU and electronic horn cards; the chassis and center rail roller wires were retained:


In the space above the Shark's speaker, I mounted a vertically-oriented piece of 3/16" clear acrylic to use as the (insulated) mounting surface for the convertor/regulator and Blunami cards.  Here's a photo of the 3" x 1½" piece and its ½" aluminum mounting angle; loco front is too the right:


You can see the Diodes, Inc. GBU-1001 FWB rectifier mounted just ahead of the acrylic piece, using the hole from the QSU mounting cylinder.

The cheap ($3.50>$8) Chinese DC>DC buck convertor/regulator is mounted on one side, using double-sided foam tape squares.  The Panasonic 1000µF 50V filter/smoothing capacitor is connected at buck converter input (left side), but is hard to see because it is the same color as the Shark carbody shell behind it.


I should note that the converter has two mounting holes, so using screws and stand-off insulators is a reasonable alternative mounting arrangement.

Don't ask about RF interference from this converter/regulator.  It certainly increased the noise floor in my workshop's Bose Wave Radio on the FM band.  I didn't work up the nerve to power-up my spectrum analyzer and take a detailed look at its emissions.  Any correlation between its performance and FCC incidental emissions regulations is, undoubtedly, entirely coincidental!  But it didn't clobber TMCC on my layout.  And when you live out in the woods, the rest isn't of much concern.

I retained the 1000µF filter/smoothing capacitor used in the bare converter scheme previously noted, now mounted at the buck regulator input.  The Blunami decoder/controller card is mounted on the other side of the acrylic piece, also using the foam tape squares.  You can see the more-visible Panasonic filter/smooting capacitor between the acrylic piece and the forward motor, above the FWB rectifier:


You really don't have a good mounting alternative to foam tape for the Blunami, as the card has no mounting holes.  I mounted it upside down, to ensure easy access to its "current keeper" port, in case that's needed.  Operation to date suggests that it's not necessary.  DC power input wires are red and black; motor output wires are yellow and green; speaker wires are both blue.

All wiring was #22 AWG.  I contemplated using #18, but the original Weaver/Samhongsa wiring was #22, the lengths short, and the current normally under 1A.  So the loss difference would be minimal and the flexibility of the #22 wire was much better.  Before applying power for the first time, one MUST check the resistance to ground from each speaker terminal and the motors' two primary connections - resolving any measurement below a megohm.  My first setup of this scheme resulted in a smoked Blunami when the voice coil lead of the speaker contacted its frame.  On the reworked version, I put heat-shrink tubing over the speaker-end solder connections  and carefully inspected the voice coil wires, in addition to checking the load-to-chassis resistances as noted above.  The speaker was new, as well.

Sitting at idle, with track powered by a Lionel Powerhouse 180, the DC>DC buck converter/regulator was set for an output of 18V.  The locomotive was run with a test train consisting of a dummy B unit, 16 "average" freight cars, and a lighted caboose.  The BluRail iPad app includes a Blunami real-time input voltage measurement display.  This never dropped below 17.8V, and then for only a short part of a 3% incline, when the entire train was headed uphill.  Speed loss upgrade didn't seem significant.  Shark trainspotters reported them as "luggers" that seldom exceeded 45 mph in real-life.  The Blu Shark seems capable of at least that, uphill, with a heavy train, but won't be a ballast burner otherwise.

There are many theoretical reasons to favor the use of the rectifier + converter/regulator over the bare-bones FWB rectifier and smoothing/filter capacitor.  The practical implementation proved those benefits - the locomotive performed consistently, regardless of train size or track gradient.  Track voltage anomalies were essentially invisible.  I'll be posting a more technical discussion of the measured data and its implications.

FWIW, while I had the Shark disassembled to implement this conversion, I also converted its pilot to a fixed mount, attached to the loco's base plate instead of to the front bogie (a/k/a truck).  This resolved a problem of the uncoupler pad shorting the center rail in certain Ross switches, but at the cost of giving the Shark somewhat of a "high water pants" look from track elevation.  Ignoring the latter, it seems to match prototype Shark pix better.  Yet ...

Headlights, markers, and electrocouplers remain on the horizon in the Blu Shark.  I set up the incandescent headlight for 3V, but it burned out after a half hour or so of operation, so that was probably too high.  It will be replaced by an LED.  A backup light LED will be installed in the B unit, connected to the Blu Shark by tether.  Marker light LEDs have their mounting challenges, but I'll look into adding them.

The bottom line is that, for medium-sized, twin-motored diesels, the Blunami controller card appears to be a worthy alternative to Lionel's TMCC and the MTH DCS, as long as one is willing to accept a smartphone or tablet as the controller surface.  I'm very pleased with the performance of my Blu Shark and look forward to implementing this scheme on an Atlas EMD switcher and (ancient) Weaver FA/FB pair.  Passenger diesels are another matter for future investigation - likely next fall/winter.



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Last edited by KarlDL
@DarrellR posted:

I could not resist jumping in on the JB Weld comment:

See my web page,, for converting a Lionel H-7 (beautiful model!) to 2-Rail and Dead-Rail, including cutting down and insulating the drivers (and filling in the traction grooves).

HOLY COW!  That looks like a ton of work to make it all work!  That's some serious mechanical skills exhibited there!

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