Electromagnetic Uncoupling That Works!

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Electromagnetic Uncoupling That Works!

Postby Gary S » May 30th, '10, 22:50

Yesterday I spent a good while getting all my e-mags ready for the layout in the new building. Since they go under the track, they have to go in before the track goes down.

First, here is a photo of an almost finished magnet. Just needs the wiring connections.

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I did alot of experimenting a couple years ago to make the Kadee system work flawlessly. With the regular HO single coil kit, the coupler/spring/draft box had to be adjusted and maintained meticuously to get 100% operation. That was tough to do. The nost common flaw was the couplers not moving far enough to the side to uncouple. So, I decided that a stronger magnet would be more likely to function correctly, even with less than perfect coupler adjustment.

So, what I did was use the Kadee O scale kit. This has 2 coils, so more magnetizing force. I wire the coils in series and operate them at 24 volts.

As you can see, I added some extra steel plates on the sides to more strongly focus the magnetic flux. I also added an aluminum plate to each side for mounting purposes. Since these mags will be installed up through 1/4" of plywood, 2" of foam, and the roadbed, the aluminum plates extend down with a 90 degree bend at the bottom so they can be screwed to the 1/4" plywood.

Here is a photo of all the parts. The stuff on the left is extra stuff I fabricated, stuff on the right is factory. I threw the ridiculous factory "thru-the-ties" plastic mounting hardware in my scrap bin.

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I cut the steel plates from some 1/32" sheet metal, then drilled holes in them to match the factory steel plates that come with the Kadee O-scale kit.

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And a pic of the sheet aluminum. This was an aluminum "kick plate" for a door, got it at home depot. I scored it with a razor knife and snapped the pieces off, then drilled them and bent the 90 degree bend with the help of a vise and hammer.

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A picture of the assembling in progress. I did have to buy longer screws to go all the way through the added plates.

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Here's a photo of 15 completed e-mags, wired and ready to go. Well, I still need to cut the exposed threads of the screws off, just to make it easier to install the mags up through the hole in the foam.

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Anyway, I had great luck with uncoupling using these on the old layout. And I'm glad I got all of these assembled up front, so once I start laying track, I won't have to stop and build magnets.
Last edited by Gary S on May 31st, '10, 09:03, edited 1 time in total.
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Re: Electromagnetic Uncoupling That Works!

Postby e-paw » May 31st, '10, 00:21

That's a great idea :tada: And some excellent craftsmanship. That's a simple and effective way to solve your magnet problem. Good work. :worship:
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Re: Electromagnetic Uncoupling That Works!

Postby andersley » May 31st, '10, 08:09

Excellent, well thought out work. I have used the HO emags in the past with varying degrees of success, your custom ones should be a great improvement. :tada:
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Re: Electromagnetic Uncoupling That Works!

Postby Ralph » May 31st, '10, 08:22

Very impressive Gary! :worship: :worship: :worship:
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Re: Electromagnetic Uncoupling That Works!

Postby Gary S » Jun 6th, '10, 22:45

Installed a few of the e-mags today. Here is how I do it.

First, mark the cork by using the magnets as a template.
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Then cut out the cork with a hobby knife.
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Drill holes down through the foam and plywood to locate the location underneath.
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I made a template to mark the hole.
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Used a jig saw to cut the plywood. Be careful not to use a blade that is too long because it will cut through the cork above.
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Next is cutting out the foam from above. The foam has to be cut out from under the cork on the edges due to the taper of the emag.
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Insert the magnet up through the foam and use screws to attach it to the plywood.
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And the installed magnets. The height is adjusted with the screws - the top of the magnet is level with the top of the cork. I'll put a piece of duct tape over each magnet to cover the hole.
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Re: Electromagnetic Uncoupling That Works!

Postby andersley » Jun 7th, '10, 04:03

Excellent job! :worship: :worship:
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Re: Electromagnetic Uncoupling That Works!

Postby OBJack » Jun 12th, '10, 04:26

Thanks Gary. An excellent solution and how to. :cheers:
I am not up to that point as yet, and I was needing to do some research on effective ways of automatic uncoupling, and it seems as if you have solved the problem with some inventive thinking.
Being the novice that I am, can I ask some dumb questions ? I don't know how they work but am assuming you flick a switch to activate the magnet?
And what is the 24v power source you use?

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Re: Electromagnetic Uncoupling That Works!

Postby Russ Bellinis » Jun 12th, '10, 13:58

Gary, I like you uncoupling magnet design. I'm curious, do you use Athearn cars with steel weights or Athearn cabooses with steel ladders? I'm asking because I saw a similar product at a train show recently. I can't remember what it was called, and the guy making them out of his garage doesn't have a web site, just an email address. I took his brochure with me and after reading it over, I found that he did not recommend any steel be in rolling stock. None of the Athearn steel weights or Tichy's use of 1/2 inch steel nuts for weights or Athearn's steel ladders on cabooses. I sent him an email inquiry because I was thinking of using some of his uncoupling magnet set ups on a module in the club, but he advised that the magnets are strong enough that they might derail cars if there is steel in them other than the Kaddee trip pin. I could eliminate steel from my cars, but since the modular set ups are a "community" layout for the entire club to enjoy, I could not expect other members to eliminate steel from their rolling stock. After I found out that his product wouldn't work for my situation, I discarded the brochure and lost his email address.

Also another question about the Kaddee O-scale coils. Will they stand a short period of time energized, or are they a momentary type that will burn out if energized for more than a few seconds? One reason that I haven't considered using Kaddee Ho-scale electromagnets on a module is that when we set up at shows anyone in the club can operate on anyone's module, so I try to avoid any momentary contact components.

I won't be using Kaddees on my home layout, since I want to use the Sergents scale couplers that require an uncoupling wand from Sergents rather than some sort of uncoupler under the tracks or between the tracks.
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Re: Electromagnetic Uncoupling That Works!

Postby Gary S » Jun 13th, '10, 00:47

OBJack wrote:Being the novice that I am, can I ask some dumb questions ? I don't know how they work but am assuming you flick a switch to activate the magnet?
And what is the 24v power source you use?


Thank you for the kind comments, Jack. I am using a 24 volt power DC supply that I salvaged from an old industrial control panel. A decent 24 volt supply rated 2.5 amps can be had for around $60, perhaps cheaper if you searched around. I like the 24 volts on the two coils in series - there is only 12 volts on each coil, less than the single coil using Kadee's recommended 16 to 18 volts. Each of my coils will run cooler and have less chance of burn-out, yet overall, the magnetism is quite a bit greater.

As for operating the magnets, I have a momentary pushbutton and control relay under the layout that operates the magnet - in conjunction with a time delay relay in the control panel. It's a nifty little circuit.... push the button and release, the magnet will stay on for five seconds, giving enough time to uncouple, then it automatically shuts off.

There is a thread showing the control panel and there is a better explanation of how the magnets work there. It may seem complicated, but it really isn't. Just some basic relay logic.

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Re: Electromagnetic Uncoupling That Works!

Postby Gary S » Jun 13th, '10, 01:19

Russ Bellinis wrote:Gary, I like you uncoupling magnet design. I'm curious, do you use Athearn cars with steel weights or Athearn cabooses with steel ladders?


Russ, all my cars are weighted with lead - because the magnets absolutely will drag a steel-weighted car around. But on that note, so will a Kadee 308 under-the-ties permanent magnet. I do weight my cars a little bit heavier than NMRA standards because it helps keep the slack out of the cars when going over permanent magnets at the spurs. I know that everyone likes to have "super-free-rolling" cars, but really they are the bane of magnetic uncoupling. It is best to have cars with just a pinch of drag in them.

I do have Athearn cabooses (with lead weights). From memory, I didn't have any issues with the ladders. I think they are small enough and high enough to not make the car roll to the magnet. >>>>> okay, I just got back from the train room. Took an Athearn caboose. The magnet had little to no effect on it. I tried it in various positions, then activated the magnet. Out of about 10 tries, there was one time when the caboose moved maybe 1/8 of an inch.

Russ Bellinis wrote:I'm asking because I saw a similar product at a train show recently. I can't remember what it was called, and the guy making them out of his garage doesn't have a web site, just an email address. I took his brochure with me and after reading it over, I found that he did not recommend any steel be in rolling stock. None of the Athearn steel weights or Tichy's use of 1/2 inch steel nuts for weights or Athearn's steel ladders on cabooses.


Sounds right as mentioned above. No steel weights!

Russ Bellinis wrote:but he advised that the magnets are strong enough that they might derail cars if there is steel in them other than the Kaddee trip pin.


I don't see how it would derail a car, but the e-magnet will definitely make a car roll toward it. But again, so will a Kadee 308. The e-mag will also attract steel axles. I use Intermountain wheelsets for the most part, which are ~almost~ totally non-magnetic - not enough to be attracted to the magnet with a weighted car.

Russ Bellinis wrote:Also another question about the Kaddee O-scale coils. Will they stand a short period of time energized, or are they a momentary type that will burn out if energized for more than a few seconds? One reason that I haven't considered using Kaddee Ho-scale electromagnets on a module is that when we set up at shows anyone in the club can operate on anyone's module, so I try to avoid any momentary contact components.


I mentioned some of this in my reply to Jack above, but first, the Kadee O scale coils are the exact same thing as the HO scale coil, you just get two of them.

Using some basic electrical math, the series twin coils at 24 volts are 33 percent stronger than a single coil at 16 volts, yet they draw only .75 the current of the single at 16 volts. Therefore, they can remain on longer without frying. I do use an automatic time delay circuit to control the magnets - push and release the button, and the magnet turns on and then turns off after five seconds (this is adjustable, but 5 seconds seems to work for uncoupling). The time delay isn't so much for protection as it is to allow both hands on the throttle.

One other thing - the twin coils could be wired in parallel and operated from a 12 volt supply.... or if a person wanted a REALLY strong uncoupler, put 16 or 18 volts on the parallel coils!

Now, with my circuit, if the button was just held down continuously, the magnet would turn right back on after the 5 second delay, so it is not FooL prOOf. But a circuit could certainly be designed to keep the magnet off for a period of time between energizations. I didn't do that because I have control over who will operate on my layout.[/quote]
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Re: Electromagnetic Uncoupling That Works!

Postby Gary S » Jun 13th, '10, 01:31

More commentary:

I often hear the Kadee system getting a bad rap. And it can be tough to make it work. I think Kadee was confronted with the issue of steel weights in cars, so they had to make the magnet weak enough not to attract cars, but strong enough to operate the couplers. This is a rock and a hard place, and requires meticulous adjustment of the couplers/draft boxes/springs. Another issue they had to face was unwanted uncouplings as a train went over a permanent magnet. Free rolling cars would sometimes have slack at the couplers and they would uncouple. or if the engine hit a spot with poor electrical contact, it would slow and create slack, or even a poor running engine would do this. Also, the steel weights would pull a car forward in a moving train, again causing slack and unwanted uncoupling.

So, the problem boils down to three things:

Steel
Free rolling cars
weak magnets

The solution:

Get rid of the steel
Heavier cars to make them have more drag (other options exist to create a bit of drag at each car)
stronger magnets.

On my old layout, the uncoupling was pretty durned close to 100 percent.
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Re: Electromagnetic Uncoupling That Works!

Postby Gary S » Jun 13th, '10, 02:18

As posted in the "WOOHOO" thread, I ran trains today. I was working on wiring for the east wall, so i rigged the power supply to it to test the DCC and magnet power. Here is the uncoulper magnets at work:

First, position the coupler of the car to be uncoupled at the electromagnet. Here the GP7 is pushing the cars onto the siding where the magnet is (magnet is located in line with the pencil).

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Stopped with the couplers over the e-magnet.

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Next, flip the direction switch so the loco will be ready to move away from the car to be uncoupled. Then push and release the button for the e-mag. The e-mag will turn on and pull the couplers apart. Use the throttle to pull away from the uncoupled car. And, we are using both hands on the throttle because the e-mag stays on all by itself. Contrast this to pushbutton only control and you have to hold the button down at the same time you are trying to control the throttle - not easy.

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And five seconds after pushing the button, the magnet turns off by itself.

Here is a pic showing the magnet causing the couplers to be pulled to the sides.

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And one showing how the delayed action works. Notice the couplers are not connected at the knuckles. The knuckles have slipped past each other because the magnet had them opened to the sides. Now we can shove the car back to spot it where we want it.

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Anyway, I like it alot!!!!! :)
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Re: Electromagnetic Uncoupling That Works!

Postby OBJack » Jun 13th, '10, 05:13

Thanx Gary. :tada:

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Re: Electromagnetic Uncoupling That Works!

Postby Russ Bellinis » Jun 14th, '10, 10:05

Nice, Gary. I'm planning a module set of the Southwest Portland Cement plant in Victorville, Ca, and was looking for a system to have automatic uncoupling. The guys in the modular club use various methods of uncoupling cars that generally involve the use of two hands on the cars to be uncoupled. I would like a "hands free". If the electro magnet just causes a car with steel weights to roll a little when the magnet is energized, that would not be much of a problem, much better than using two hands to uncouple cars or using a permanent magnet with the problem of nuisance uncoupling. My system would be operated by anyone in the club participating in an operating session, so I would like it to be fool proof. Do you have any part numbers for the time delays, and do you know of a time delay that would energize for 5 seconds and then do a forced de-energize for 30 seconds before being allowed to activate again? One other question, would the rolling caused by steel weights in car pull the couplers away form the magnets so that they would not uncouple? It suddenly dawns on me that a flat weight like used by Athearn or steel weights mounted in the center of the car could cause the couplers to move past the magnet or cause an uncoupled car to "follow" the train and recouple when it cleared the magnet.
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Re: Electromagnetic Uncoupling That Works!

Postby Gary S » Jun 14th, '10, 11:36

Russ Bellinis wrote:If the electro magnet just causes a car with steel weights to roll a little when the magnet is energized, that would not be much of a problem, much better than using two hands to uncouple cars or using a permanent magnet with the problem of nuisance uncoupling. My system would be operated by anyone in the club participating in an operating session, so I would like it to be fool proof. One other question, would the rolling caused by steel weights in car pull the couplers away form the magnets so that they would not uncouple? It suddenly dawns on me that a flat weight like used by Athearn or steel weights mounted in the center of the car could cause the couplers to move past the magnet or cause an uncoupled car to "follow" the train and recouple when it cleared the magnet.


Russ, it was about 4 years ago that I was perfecting the system, so I don't remember exactly how the steel-weighted cars reacted, although it was definitely adverse.

The best thing to do would be make a mock-up track and then play around with the system. You'd need a Kadee o-scale e-magnet, a pushbutton rated for a couple amps, a power supply, and some track. Maybe take a 1 x 4 and cut a hole in it, mount the magnet underneath, spike several lengths of flex track to the board, and then do some practice uncoupling runs with various cars and methods. I like my 24 volt system because 24 volt DC relays are easy to find. As I mentioned previously, you could use 12 volts on the system, just put the coils in parallel instead of series (Note: it is important to make sure the current flow is going in the same direction in both of the coils). With the mock-up, just use the pushbutton to energize the magnet, don't worry about a time delay. Just experiment to see if the rolling cars are too much of a hassle.

The 24 volt series coil arrangement pulls about 1.5 amps. Parallel at 12 volts would pull about 3 amps. Your power supply would have to be able to handle that. Maybe you have an old power pack that would serve for the experiment?

Russ Bellinis wrote:Do you have any part numbers for the time delays, and do you know of a time delay that would energize for 5 seconds and then do a forced de-energize for 30 seconds before being allowed to activate again?


I don't know of a time relay that would do that function, but a simple combination of two "ON" delay relays and two "regular" relays would accomplish that. As for part numbers, that would depend on the voltage you will be using. Let me know.

If you decide to do the experiment, let me know, I'd be happy to lend technical support and wiring diagrams. :)
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