Powered UP to Power Functions adapter

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I like the new Powered UP (PUP) system in general -- the BlueTooth aspect is intriguing especially for the possibilities for complex behaviors controlled by a computer/phone/whatever.  However, I also have a significant amount of Power Functions (PF) equipment in my collection which I'm not ready to give up on just yet.

So, my first goal was to get old Power Functions motors working with the new Powered UP Hub.  Lots of people have already demonstrated that this is possible, but I wanted to show my way -- which I think is relatively clean and modular.

First, the hard part -- getting a Powered UP cable.  I ended up adding Powered UP LED Light (88005) to a recent order from the LEGO shop with the intention of sacrificing the light just to get the cable.  This is painfully expensive ($10 for one cable/connector!), and I won't be doing it again, but it was the least bad way I could think of to get a cable for experimentation.


Then, hacking up the cable.  Borrowing from @JopieK's PUP teardown work:


I connected pins 1 and 2 to standard Dupont female pin headers.  Next, I connected together pins 3 + 6, as well as 4 + 5.  This signals to the Hub what type of device is attached -- in this case, it looks like a PUP Train Motor.  Then, I sealed away my hacked wires behind a bit of heat-shrink tubing to protect the work and make it look less ugly.


Hacked Lego Powered Up cable



Next, I sacrificed a PF Extension cable.  This is significantly less painful, because the extension cable only costs a third of what the lights cost and I end up with two usable connectors ($1.50 per cable/connector).

For this, I connected the two center wires to standard Dupont male pin headers.  These are the wires that actually carry the power to PF motors.  I left the outer two wires unconnected.  Again, a bit of heat-shrink tubing to clean things up.

Hacked LEGO Power Functions cable


Now, I can just plug the male end (PF) into the female end (PUP), plug any PF device into the connector, and control it from the PUP Hub.

LEGO Power Functions motor connected to Powered Up Hub

I chose Dupont-style connectors because: I had them on-hand already; they're very simple to "breadboard" into test circuits; they're not polarized.   This last fact means that it's simple to "reverse" a motor; if you don't like which way it rotates when you press +, just unplug the wire and plug it in backward!


And a video of it in action.


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After getting that done, I was curious what else I could accomplish with this fairly simple wire splice technique.

I have some trains where I use two PF Train Motors on the engine to give the pulling power I wanted (for example, Horizon Express.)   I wondered: Could I upgrade this to Powered Up BlueTooth control, while keeping the pulling power of two motors, AND potentially saving some money by reusing the PF motors I already have?

Thus was born idea #2: hack a socket into the middle of the PUP Train Motor cable.  I used the same Dupont-style female connector that I used on my original hacked cable, so I can use the same hacked PF cable as well.  I simply soldered some extra wire onto the same pins 1 and 2, added the connectors, and heat-shrinked the mess.  Then I plugged my adapter cable in and connected a PF train motor.  Now, when I tell the PUP Hub to run the PUP Train Motor, both motors receive the same power simultaneously.

Again, as the connectors are not polarized, I can simply turn the cable around to change whether the motors spin the same direction or opposite directions.

One very interesting thing that this experiment brought to my attention.  I had assumed that the only real difference between the two was the small additional circuit board atop the motor that connected the ID pins appropriately, but that seems to be incorrect. The actual electric motor inside the two versions of the Train Motor do NOT seem to be the same.  Notice in the video when both motors are receiving power simultaneously.  The PUP motor spins easily and powerfully at speed 1.  The PF motor, as always, does not really generate sufficient torque to spin (even with no load) until speed 2 or 3.  As the two motors are receiving identical power, this difference is clearly inherent to the motor itself, not simply a difference in the driving circuitry between the PUP Hub and the PF IR Receiver.  The PUP motor seems to be higher quality/more powerful.

It's difficult to tell from the video, but the PUP motor is also noticeably faster than the PF motor at the same speed settings.  The speed difference is enough that I didn't even bother trying it on an actual train; it's clear that the PF motor would be a drag on the PUP one.  This isn't just some sort of weird behavior that only appears because the Hub is powering two motors when it only expected one, either.  Hooking up my original spliced cable to the PF motor (no PUP motor involved) produced the exact same results -- PF motor doesn't generate significant torque until speed 2 or 3.  I verified that it wasn't just one bad unit by testing three separate PF train motors.


So, my final conclusion is:

The hacked cable allowing PF motors to be used with the PUP Hub is useful, but

Mixing PUP and PF Train Motors together on the same train is probably a bad idea.




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Wow, thank you for the information! Would it be a good idea to take directly PUP train motors to get the PUP plugs? The motors will be used anyway and there is no hardware waste.

Edited by Giottist

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16 hours ago, Giottist said:

Wow, thank you for the information! Would it be a good idea to take directly PUP train motors to get the PUP plugs? The motors will be used anyway and there is no hardware waste.

That would be the less painful way to go. I recycle the PF cables from my motors and put Dupont connectors on them. You could put another ribbon cable into the motor and Dupont connectors on the ends. Dupont connectors are quite useful. 




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