On-board uncoupling

[Robin2]

Having freed ourselves from the shackles of track-borne power and control it seems logical to think about being able to uncouple trains anywhere on a layout just like the real thing.

 

I've been thinking about how this might be done sufficiently cheaply that one might be able to afford to install devices in several vehicles. I'm think about a cost per unit of less than £10 and preferably about £5.

 

I was very surprised when googling "dcc uncoupling" turned up a lot of hits including these

 

http://www.rr-cirkits.com/uncoupler.html

http://www.2mm.org.uk/articles/dcc_couplings/index.html

 

Is this something that people may be interested in?

 

Perhaps StuartM has an update on the 2mm example?

 

...R

[Robin2]

I now have my on-board uncoupling working. I hope it can be seen in this short video 

 

It works by listening for a command from an infra-red transmitter. As I have programmed it there can be 250 different addresses and it would be trivial to re-program so there could be thousands of addresses.

 

The mechanical part is a modified DG coupling with a lever that is pulled by an electromagnet when the receiver recognizes its address.

 

When it is idle there is very little current draw from the battery and it only needs a heavier current for a second to operate the uncoupler so a full charge should easily last for a whole day.

 

...R

[Guest 40-something]

Hi

 

I'd like to know more about your uncoupler. Im a 4mm modeller with an end to end goods yard layout currently relying on magnets uncoupling Kadee's but I find the idea of Infra Red control fascinating.

Could you give me some ideas with regards components etc?

[Robin2]

The nerve centre is an Atmel Attiny45 microprocessor programmed using the Arduino system. I'm happy to share the program. If I had space (as in an OO/HO vehicle) I think I would use the bigger Atmel Atmega 328 chip which would be a little easier to program. The Attiny program will also work on a 328.

 

The infrared signal is detected by a Vishay TSOP4838 IR detector which is very clever and saves a lot of hard work. It's the black shiny thin to the left in the picture.

 

My wagon as a modified DG coupling extended to have a lever poking up into the body which is pulled by an electromagnet. The electromagnet is home made using 0.15mm enamelled copper wire from Maplin.

 

A small PNP transistor (BC337) is used to allow the Attiny to switch the current in the electromagnet, and there are two resistors - one to limit the current in the base of the transistor and one to do the same for the electromagnet.

 

The battery is an 80mAh Turnigy Nanotech (whatever that means) from HobbyKing. It's about 7mm diam and 30mm long. I also use these to power my locos.

 

I have cut a hole in the wagon floor so the Attiny can stick through. It would only be noticeable from the outside on close inspection.

 

This is a picture of the electronics out of the wagon

 

 

...R

 

[Guest 40-something]

Thanks for that, very interesting, I'll study all the bits over the weekend and most probably will come back with more questions!

 

Thanks again

[Robin2]

I forgot to say that in an OO/HO vehicle (or larger) I would probably use a small servo to operate the uncoupler. That would add about £5 to the cost but could probably be made to work any of the standard couplings. Servos also have the advantage that they will stay in different positions without power if the load on them is low. Writing programs to control servos is very simple with the Arduino system.

 

...R 

[Guest 40-something]

I forgot to say that in an OO/HO vehicle (or larger) I would probably use a small servo to operate the uncoupler. That would add about £5 to the cost but could probably be made to work any of the standard couplings. Servos also have the advantage that they will stay in different positions without power if the load on them is low. Writing programs to control servos is very simple with the Arduino system.

 

...R 

Thanks again R

 

I have a few questions... 

 

Would you happen to have a circuit diagram for a basic set up?

Regarding servo's, where could I pick them up?  (I've googlised but still have no clue!)

 

This may be incredibly stupid but...

 

I have an old SKY remote control, would I be able to use that?

 

Thanks again for your help

 

Joe

[The Bigbee Line]

I think the use of remote uncouplings is down to the individual and the thickness of wallet. 

Recently Kadee have introduced remote equipment for G and gauge 1 http://www.remoteuncoupling.com/

It will only be a matter of time before the do something for HO.  Likewise MTH and Roco have supplied certain locos with controlled couplers.  Usually with the buckeye type coupler lowering to achieve disengagement.  The re is also a guy doing kits to fit in boxcars either single of double ended.

[Robin2]

I hope my idea will appeal to people with thinner wallets!

 

...R

[Guest 40-something]

I hope my idea will appeal to people with thinner wallets!

 

...R

My wallet is pretty thin!

[StuartM]

Having freed ourselves from the shackles of track-borne power and control it seems logical to think about being able to uncouple trains anywhere on a layout just like the real thing.

 

I've been thinking about how this might be done sufficiently cheaply that one might be able to afford to install devices in several vehicles. I'm think about a cost per unit of less than £10 and preferably about £5.

 

I was very surprised when googling "dcc uncoupling" turned up a lot of hits including these

 

http://www.rr-cirkits.com/uncoupler.html

http://www.2mm.org.uk/articles/dcc_couplings/index.html

 

Is this something that people may be interested in?

 

Perhaps StuartM has an update on the 2mm example?

 

...R

Hi Robin,

Yes I've seen the 2mm example, excellent though it is, it is limited to DCC, and is only able to couple/uncouple the loco, so unless you were using power through the tracks and shunting complete rakes of stock its not much good. But it does prove a theory.

I've though about this a little and like you've discovered it would need a battery and pic, plus receiver in each item of stock, which is possible and perhaps cost prohibitive?

[Robin2]

@40-Something, I seem to have missed your post on 20 October and never answered your questions - apologies. It may be too late now but here are my answers ...

 

I will try to produce a circuit diagram later today.

Servos are widely available for model aircraft. Hobby King is a big online seller.

 

Technically you probably could use a Sky remote but it would be whole lot of trouble because you would have to figure out the codes it transmits and then program your uncouplers to respond to those codes.

 

@StuartM - I reckon the cost per vehicle is under £5 if you are content with an IR signal. Wireless would make it considerably more expensive. Of course a loco with wireless control wouldn't need IR as well.  I don't think it would be necessary to have one in every vehicle if you plan what shunting moves you want to make. It would get very complicated trying to distinguish between 50 or 100 items of rolling stock if each one had an uncoupler.

 

I think the choice is between having a limited number of places to uncouple but being able to uncouple any vehicle using a ground-based system OR being able to uncouple anywhere but with only a limited number of vehicles using an on-board system.

 

...R

[Guest 40-something]

@40-Something, I seem to have missed your post on 20 October and never answered your questions - apologies. It may be too late now but here are my answers ...

 

I will try to produce a circuit diagram later today.

Servos are widely available for model aircraft. Hobby King is a big online seller.

 

Technically you probably could use a Sky remote but it would be whole lot of trouble because you would have to figure out the codes it transmits and then program your uncouplers to respond to those codes.

 

@StuartM - I reckon the cost per vehicle is under £5 if you are content with an IR signal. Wireless would make it considerably more expensive. Of course a loco with wireless control wouldn't need IR as well.  I don't think it would be necessary to have one in every vehicle if you plan what shunting moves you want to make. It would get very complicated trying to distinguish between 50 or 100 items of rolling stock if each one had an uncoupler.

 

I think the choice is between having a limited number of places to uncouple but being able to uncouple any vehicle using a ground-based system OR being able to uncouple anywhere but with only a limited number of vehicles using an on-board system.

 

...R

Hi

 

Thanks for your latest post, would like to see that circuit diagram when you have the time to post, its still something Im thinking of incorporating into my layout

[Robin2]

Hi Joe,

 

I have attempted to draw a circuit diagram and as I had made the whole thing as I went along I am no guaranteeing that it is correct. In any case a great deal depends on how the Attiny is programmed.

 

Basically the power for the TSOP is taken from the Attiny so that it can be switched off to save power. The output from the TSOP is read as serial data by the Attiny. If it receives its own ID code it switches on the current in the electromagnet via the transistor. The resistors are just to limit the current. It is powered by a single cell LiPo which gives 3.7v.

 

The Attiny runs at 1MHz to keep the current draw down and that meant I had to write my own code to interpret the serial data.

 

I'm happy to share all the code but if you are completely unfamiliar with the Arduino system it may not make sense. Also there must also be code for an Arduino Uno to transmit the IR data and for the PC that tells the Uno what/when to transmit. It would be possible to program the Uno so a PC is not needed but that would require some sort of keypad and probably an LCD display.

 

...R