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Digitrax accessory to drive a Kadee Electromagnet Uncoupler

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  • Member since
    January 2021
  • 32 posts
Digitrax accessory to drive a Kadee Electromagnet Uncoupler
Posted by Oldngrey on Monday, March 29, 2021 3:17 AM

I've got a few Kadee 309 Electromagnet uncouplers and looking for some advice on how to drive them from DCC.

I've been watching the DCC Guy and seen his advice on using a timer board to drive the uncoupler. That bit's fine. So a short pulse is needed to set off the timer.

Now for the fun part. I don't want to use a momentary button as I am going to make this layout free of the traditional switches on a control panel. So that means controlling it via DCC and JMRI.

So, what Digitrax product should I use to provide this pulse? 
I've looked at the TF4 and TL1 function decoders which look to be ok.
I've also looked at using one of the outputs of a DS64.
Anyone got some advice on this?

 

  • Member since
    January 2021
  • 32 posts
Posted by Oldngrey on Tuesday, April 13, 2021 6:54 AM

In case anyone ever searches this for an answer, here is something that does work. It's obviously not the cheapest solution and involves more components than I wanted.

I use a DS64 and set the opsw 4 to closed, which means that when I throw it from a DCC throttle or JRMI it ouputs a 800mS pulse output.

Since a lot of components don't have a common earth, I used a relay between the DS64 and the next component. The 800 milli-Seconds ensures the relay reliably operates. (It's a fairly standard 12volt dpdt relay.)

This relay simulates the button, and in fact the normally open contacts are wired exactly like a button.

The electromagnet uncoupler needs to stay on for a while (eg 30 seconds) to allow enough time to drive rolling stock over it and do the uncoupling. Because the DS64 can't be programmed to throw the switch for 30 seconds, I then had to use a timer board in between the DS64 and the electromagnet. These boards are cheap and readily available on eBay and can be easily set to opeate the uncoupler for 30 seconds. That's good, because nothing else here is cheap.

As far as powering this mess, the DS64 works best with a 12-14v power supply on the AX1 and AX2 connectors so as to not steal power from the track bus. I've read that you should power all your DS64's on a single power supply. Not great news, as it means yet another bus cable under the layout. The timer board needs a 12v power supply too. And the uncoupler needs a 16v power supply capable of 3Amps.

Overall, I can see why nobody answered my post as it's really not a cheap solution and isn't elegant at all. So how do others run electomagnet uncouplers from DCC?

  • Member since
    December 2004
  • From: Bedford, MA, USA
  • 21,333 posts
Posted by MisterBeasley on Tuesday, April 13, 2021 10:31 AM

The Kadee electromagnetic uncouplers take an inordinate amount of power.  They would probably burn out a normal decoder pretty quickly.  I actually worry about burning out the pushbuttons I use for my uncouplers from the arcing.

You might be able to power a relay with DCC and use that to drive the magnet coils.

It takes an iron man to play with a toy iron horse. 

  • Member since
    January 2009
  • From: Bakersfield, CA 93308
  • 6,526 posts
Posted by RR_Mel on Tuesday, April 13, 2021 11:35 AM

Why do you want to control a high current uncoupler with DCC?  I operate dual mode, DC or DCC and have two Kadee Electrics.  It’s pretty simple to just push the uncoupling button on my control panel to uncouple.

I would find it awkward to use my DCC controller to operate both simultaneously.
 

Mel



 
My Model Railroad   
http://melvineperry.blogspot.com/
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.

  • Member since
    December 2004
  • From: Bedford, MA, USA
  • 21,333 posts
Posted by MisterBeasley on Tuesday, April 13, 2021 1:01 PM

RR_Mel

Why do you want to control a high current uncoupler with DCC?  I operate dual mode, DC or DCC and have two Kadee Electrics.  It’s pretty simple to just push the uncoupling button on my control panel to uncouple.

I would find it awkward to use my DCC controller to operate both simultaneously.

Mel

I do agree with that sentiment.

I added staging and a few turnouts on a new part of my layout.  To minimize wiring, I got a stationary decoder and just wired them for DCC.  I found it kind of inconvenient to lose control of the train I was running just to align the turnouts.  Uncoupling requires even closer coordination between the uncoupling magnet and train motion.  You need to HOLD the couplers open while you simultaneously pull away or they will recouple as soon as the magnet shuts off.  Using Kadee's delayed uncoupling feature would be tricky.

It takes an iron man to play with a toy iron horse. 

  • Member since
    January 2021
  • 32 posts
Posted by Oldngrey on Tuesday, April 13, 2021 9:02 PM

Yep, agree with all the comments.

Yes the kadee electomagnet uncouplers take a lot of power (3Amps). That's why I am driving it with relays and a separate power supply. Pressing the DCC "button" gives me 30 seconds to uncouple.

My goal was to have no physical control panels at all and rely on a tablet and DCC. At first thought it seems a logical way to the future but the cost seems to be prohibitive. I think I've sorted out the convenience problems mentioned in a couple of replies.

Thanks for the comments though. Appreciated. I'm not trying for the cutting edge, and traditional methods work because they are tried and tested.

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