How could I provide power and/or data coupling between train cars?

[TK2241]

Hello all,

I'm trying to find a way to create a power/data coupling between train cars that can be connected/disconnected like the car coupling magnets. Has anyone done anything like this?

Background: This is so that I can supply power and control to LED lights (and maybe other devices) in the cars being pulled behind the engine, which will provide the power and control unit (Arduino based MCU)

I've tried using a micro USB magnetic connector, but they are too bulky and don't flex easily enough for this.

I'd love to find out if anyone has engineered anything similar.

Thanks in advance!
Arlo

[JopieK]

You could use small magnets, I don't have experience how easy magnets are to solder to though and make sure you properly insulate them. Are you going to use i2c then or? For i2c you will already need four wires you know... 

[TK2241]

Well, I just found these: https://www.alibaba.com/product-detail/Customized-powerful-magnetic-usb-5-pin_60628607437.html

If I can buy less 5000 of them, that might just work 

And I would need to build some sort of swivel system like the magnetic car couplers.  I was thinking maybe on top of the cars for ease of building.  Definitely need to find some ideas on that...

2 hours ago, JopieK said:

Are you going to use i2c then or?

Not entirely sure yet. Basically I'll have five wires, two for power, and three for data.  Leaving my options open for now.

For my LEDs I've got one wire (three reall, vcc, ground, and one data) addressable strip, but I'm also looking in 1-wire devices.

[legoboy3998]

I couldn't find the one I was looking for, but these might work.

https://www.walthers.com/catalogsearch/result/?q=Mini+connectors

 

Sal

WFB, WI

[dr_spock]

I am not sure how big those USB magnetic connectors are.  Couldn't you mount them on top or at the bottom of the LEGO magnetic coupler enclosure?  Kind of like the couplers for M.U. trains or trolley cars that have connection points for electrical signals.  You may have to use thin wire wrapping wires to allow for flexing or recycled earbud cables.

[davidzq]

I would just use small pin connectors, with a couple extra inches of wire that can be tucked into the car. Only downside is if you use male and female connectors, the cars have to be facing the right direction, but I wouldn't see this being an issue with most trains.
The connectors can be quite small. With 5 conductors, it could be about the size of a 1x1 brick.

[TK2241]

1 hour ago, dr_spock said:

 

I am not sure how big those USB magnetic connectors are.  Couldn't you mount them on top or at the bottom of the LEGO magnetic coupler enclosure?

 

I believe they're about the same size as the coupler magnets.  But, I'll have to see if I can get them, and how much room there is to work with it.  If they can be mounted on top of the existing magnet, that would be ideal.

 

1 hour ago, davidzq said:

 

I would just use small pin connectors

 

Yeah, but I want magnetic "self-locating" connectors so that I can automatically couple/decouple them.  I think the magnetic USB connectors I found might work - I'm waiting to hear back from the company in China.

[Phoxtane]

Maybe you could attach metal foil to the magnets on the trains themselves - you could at least do automatic power connections between cars that way, assuming you left enough loose wire to let the magnets swing freely.

There's also pogo pins - fill up a 1x1 Technic brick with some hot glue to locate them, and you could have matching contacts on the other coupler that the pointy bit fits into.

[skaako]

I have exactly the same dilemma as I'm trying to feed lighting through my Horizon Express and wanted something that could easily be connected and disconnected.

 

On 4/14/2017 at 11:23 AM, davidzq said:

I would just use small pin connectors, with a couple extra inches of wire that can be tucked into the car. Only downside is if you use male and female connectors, the cars have to be facing the right direction, but I wouldn't see this being an issue with most trains.
The connectors can be quite small. With 5 conductors, it could be about the size of a 1x1 brick.

I settled on using the simple pin jumper cables used for hooking up breadboards. Easily available and very cheap.. pre-wired and use the longer cables so i can get a male and female by cutting one in half. If I can find a smaller connector would be nicer but all the extra time to wire them up outweighs the benefit for me.

I am using addressable led strips so all the carriages have to face the same way but they can be put in a different order and work by re-configuring the program. I only need 3 pins for 5V, Ground and Data so if makes the cabling less bulky. All the carriages are wired with the male plug one end and female the other so I can't get them the wrong way around 

 

On 4/14/2017 at 0:28 PM, TK2241 said:

I believe they're about the same size as the coupler magnets.  But, I'll have to see if I can get them, and how much room there is to work with it.  If they can be mounted on top of the existing magnet, that would be ideal.

Yeah, but I want magnetic "self-locating" connectors so that I can automatically couple/decouple them.  I think the magnetic USB connectors I found might work - I'm waiting to hear back from the company in China.

It would be good to know if you could get something like this in small orders.. I would interested as well. Although the last time I approached a Chinese company with a request their minimum order was 10,000 

 

[brickostan]

On 14/4/2017 at 6:17 AM, Phoxtane said:

Maybe you could attach metal foil to the magnets on the trains themselves - you could at least do automatic power connections between cars that way, assuming you left enough loose wire to let the magnets swing freely.

There's also pogo pins - fill up a 1x1 Technic brick with some hot glue to locate them, and you could have matching contacts on the other coupler that the pointy bit fits into.

I tried this:

 

[ALCO]

I have been thinking about this for a while... While I have not come up with any solutions for providing power, I have been devising a solution for the data side of this topic using these infrared components. An emitter on the right side of both ends of a car and a receiver on the left side of both ends of a car. That way when you have cars coupled together the emitters and receivers of the two cars are lined up. My evil plan to save the world included using Arduinos (sp?) In each car so that each car has a unique ID. That way you could know exactly which car is in your manifest and in what position. You would also be able to operate unique features that are on each car. This is really delving into the theory of my scheme. However we com back to the Power issue unless you pack batteries on each car but that would greatly increase the weight. Boy, if someone could figure out the Power issue... That would be amazing!

I cannot seem to be able to paste a link to the IR components on Amazon but the emitters are 5mm and the receivers are 3mm so they would work great with Lego!

[igordost]

Hi. My solution is based on jewelry magnetic locks attached to Lego buffer. More details in Flickr

Cheers

[Xris]

2 hours ago, igordost said:

Hi. My solution is based on jewelry magnetic locks attached to Lego buffer. More details in Flickr

This is a really nice solution! (The remaining problem is a working solution for decoupling the wagons...)

Respect!

Christian

[ALCO]

Now that is a great solution for power! I just might have to play with that... And look into the IR emitters and receivers I found on Amazon coupled with an Arduino board on each car.

[TCRR Constitution]

I like the idea, but I don't want to modify any parts.

[Trekkie99]

8 minutes ago, TCRR Constitution said:

I like the idea, but I don't want to modify any parts.

Much has changed on the subject of purism.

[igordost]

14 hours ago, TCRR Constitution said:

I like the idea, but I don't want to modify any parts.

Actually you don't need to. You may leave magnetic barrels free, without glueing etc. They will attach themselves to main magnet from buffer.  The only problem is during decoupling - it has to be done carefully to avoid breaking circuit. 

Another limitation of this solution -  cars have to be connected always in the same direction 

Edited May 15, 2017 by igordost

[CrispyBassist]

On 5/14/2017 at 4:18 AM, igordost said:

My solution is based on jewelry magnetic locks attached to Lego buffer.

Those even look a lot like MU couplers, which often have power transfer built in. I might have to try this too...

[Xris]

Hi,

6 hours ago, igordost said:

Another limitation of this solution -  cars have to be connected always in the same direction 

You can easily overcome this using a bridge circuit to connect any load to the train energy bus.

Christian

[igordost]

On 15.05.2017 at 8:32 PM, Xris said:

Hi,

You can easily overcome this using a bridge circuit to connect any load to the train energy bus.

Christian

I'm not sure if it is so easy... :) For 1 passenger car it's fine but when going to connect 2 or more (in chain), it becomes more complicated because car could be connected from both sides what means that input should be able to work as output as well, and vice versa. Any hints are very welcome.

Edited June 1, 2017 by igordost

[LEGO_duden]

You can feed the 2 wires straight through the wagon, and just tapping them off to a rectifier bridge. This way the polarity on the wires does'nt matter.

If you are concerned about the voltage drop across 2 diodes, schottky diodes will help. But the 9V available in PF should be sufficient.

You can even modulate the powerline and decode commands in a attiny10 for instance. No, I have not done this, but it should be doable.

[igordost]

2 hours ago, LEGO_duden said:

You can feed the 2 wires straight through the wagon, and just tapping them off to a rectifier bridge. This way the polarity on the wires does'nt matter.

If you are concerned about the voltage drop across 2 diodes, schottky diodes will help. But the 9V available in PF should be sufficient.

You can even modulate the powerline and decode commands in a attiny10 for instance. No, I have not done this, but it should be doable.

Thanks, now I see it. Two lines running through all wagons with rectifier bridge connected parallel in each wagon. Tomorrow I'm off for bridge shopping :) Cheers!

[Lowa]

When I discovered this thread I couldn't resist giving this a try with 3D printing.  The solution of @igordost is very neat but I agree with @TCRR Constitution that ideally it should not require any modification of the original LEGO coupling.  Luckily LEGO added a stud at the bottom of the coupling.  I had some 3mm magnets in stock so I designed a small brick that you can stick on the stud of the coupling and that can hold 2 magnets.

I made a couple of prints to fine tune the dimensions.  I added the magnets and wires:

and snapped it on the train coupling

 

It seems to work perfectly!  I made a little video.  The car on the left has the battery, the car on the right has an LED.  When you connect the cars, you connect the LED to the battery and it lights up... 

Any thoughts, comments ?

 

Edited June 1, 2017 by Lowa

[Tcm0]

Looks good. Is it possible to attach two of the parts to one coupler to have four wires (required for data transfer like I²C)?

[Lowa]

2 minutes ago, Tcm0 said:

Looks good. Is it possible to attach two of the parts to one coupler to have four wires (required for data transfer like I²C)?

Thanks!

Yes, putting a second one on top of the coupling seems to be possible.  It does start looking quite bulky though...

For the power + data connection I was thinking about getting some magnets that are slightly smaller (2mm diameter instead of 3mm) and arranging them like this:

That would be a lot more elegant than using 2 connectors with 2 magnets.  My only worry is the alignment of the magnets.  2 magnets will always make contact, with 4 they will have to be flush enough to make the electrical connection...  I'll give it a try!