Atlas Switch Machines Melting

[StewRRFan]

Thanks Paul. 

It has been multiple switches over time.  The wiring is from the transformer to the switch machines that are connected in series.  Nothing in between.
Any suggestions?

Ross

[M.C. Fujiwara]

My daughter learned what "momentary" meant in a similar way on the N scale 4'x4' Christmas Tree train my Dad and I built 25 years ago:



Turnout still works, so we made it part of the scene.

Going to rip out all the coffins and put in slide switches or Bullfrogs this year anyway.

[Atlas Paul]

Something has to be closing the circuit - either a bare wire is touching something somewhere, or a button is getting pushed down or stuck down when it shouldn't be, or some other oddity.

[VonRyan]

I'd just use the old article from MR and mount the machines under the switches and rewire them with a spdt toggle switch and a momentary push button. It gives you positive indication of the turnout's direction as well as still being a momentary throwing system. I use the method on the local panel for my N-Trak module and put the momentary buttons on the track diagram while maintaining a bank of toggle switches with corresponding labels as to their correct turnout. Course on my module i'm using Peco twin coil machines, but on my HCD layout in its need of restoration, it has atlas turnouts with their "piece of discarded military equipment" machines, and when i get around to removing them, i'll probably sell them to make way for code 55 and ground throws.

-Cody F.

[GRSJr]

The layout does have the Atlas Blue Button controllers.  Are you suggesting scrapping these and what would be your suggestion?

Use the  BCD circuit. It only takes a simple DPDT toggle and a small capacitor for Twin-coil maxhines. Add 2 resistors and a Bi-colored LED for illuminated indication if desired.

It'd inexpensive, compact, totally reliable and safe. In use by hundreds of modelers.

E-mail m if you're interested.

Ray  GRSJr at att.net

[PAL_Houston]

On a previous layout I had all sorts of problems with melting the switch coils.  Invariably this was owing to on of the momentary contact switches sticking in an "on" state, instead of reverting to the neutral "off" state.  What then happens is that your switch coil has to dissipate current, which it willingly does up until it melts down...

If you have a bunch of coil switches and you are going to be using them for awhile, then what you need is a capacitive-discharge circuit.  What this does is isolate the switch coil from the momentary contact switch via a circuit that will provide a very short high energy pulse to the switch coil.  After that it removes all current until there is another pulse, (usually in the opposite direction.)

If you are interested to build one yourself let me know I will go see if I can find a circuit diagram.  If not, I believe there are a number of commercially manufactured alternatives that will do what you need.

[StewRRFan]

Paul -  Thanks.  I would like the circuit diagram if it is not too much trouble.  I went through the wiring again and cannot see where it might be shorting.

Ray -  I already have your plans from a previous email.  I plan on using this when I start construction on the new layout.

Ross

[TiVoPrince]

Melting 
twin coil switch machines has been a model railroading rite of passage, forever.  At least since I was a kid learning to replace one in the 'field' without destroying anything made you part of the model railroading fraternety...

[PAL_Houston]

Paul -  Thanks.  I would like the circuit diagram if it is not too much trouble.  I went through the wiring again and cannot see where it might be shorting.

Ray -  I already have your plans from a previous email.  I plan on using this when I start construction on the new layout.

Ross

Ross:  better yet, here is a link: http://www.awrr.com/cdsupply.html.  I built one of these and permanently embedded it into the layout wiring.  So it went with that layout when I sold it.  But, it proved to be very reliable for the 2 years or so I used it.  (just remember to throw a few switches AFTER you turn off your layout power!!  This will prevent you either surprising or zapping yourself unintentially!   )

This guy, Fred Horne, is an electronics genius and very practical.  He was also very helpful when I asked questions by e-mail.

If you poke around his website, there are bunches of interesting things there that you may find of interest or helpful.

Good luck

[hpwrick]

There is a concern I have here with the Atlas Switch Machines.   I hope you won't mind my tossing in my two cents.   I've only been playing with these tinker toys since I was 12 and am 62, that is until September get's here.    You do the math.     Can we say, from the voice of stupid mistakes, lessons learned the hard way....the voice of experience?  Grin!

I've read here with some interest an authoritative discussion on how to solve these problems.    And, worry when newbies take a read considering what is written to be gospel.   As in newbies helping other newbies make the same mistakes.   While others, perhaps more experienced, make it almost to complicated...if you get my drift.

I' ve never been a fan of Atlas switch machines and usually look for other alternatives when it comes to automating my switches.   
May I suggest you look at under the table switch machines by other manufacturers.    Ie., Tortoise or other alternatives such as  a manual choke cable.   

What I don't like about Atlas switches, should you follow the advise here and you power them up at 18 volts, they throw to hard and with a loud click or bang, is much easier to cause a melt down and they tend to bend the moveable points inward.    Derails!     At 12 volts they are quieter, less likely to melt down and seldom bend the moveable points inward.

I built an O scale (three rail) train layout for a friend of mine and used the O Scale Atlas Switches. (The best out there)  and bought a Radio Shack 12 volt AC power supply.   Works smoothly and quietly.   

Never mind the gawdy looking switch machines sitting next to the track switch.    One way to mess up a great looking layout.    Available at your LHS is  something similar in size for N scale.    Gosh what are they thinking?   Used as a under the table mount would be perfect and I think that is what they are for.     At least that get's them out of view and no longer topside.

Does that help?

[peteski]

Rick, the capacitive discharge supply eliminates of all the worries you have. It will not burn out switch machines whether it supplies 12 or 16 or 18 volts.  It will not burn out switch machines if the button sticks or is held too long.

It only costs few dollars to build and it is not some complicated modern electronic wonder but a very basic circuit using same components which have been used since the infancy of electronics.  Even someone who is all-thumbs when it comes to electronics can easily build one of those units.

As far as your experience goes and the gospel you dispute (from others including Paul Graf from Atlas), there is validity to what they say.  The higher voltage (supplied momentarily) provides stronger magnetic field to move the core inside the solenoid for reliable throwing.  You might just have some really smooth throwing machines and you can get away using 12 volts, but like Paul said, they were designed to reliably throw at a higher voltage.

Actually, the way I see it, the machines were originally designed to work with the voltage supplied by the accessory terminal of all the standard 12V power packs (which have been in use probably even before even you were born).    Accessory terminals are normally powered directly from the secondary transformer winding which also (after being rectified) supplies the variable DC circuit. The secondary winding supplies between 16-20V to compensate for the losses caused by the rectifier needed to convert the AC to pulsing DC.  Makes sense?

[Freight Train]

Atlas switch machines need 16-18 V AC to operate properly.  The MRC 1300 probably only has enough amperage to throw one machine at a time, maybe 2 if you are lucky.

If only one machine is melting, then the problem could be with the button.  If more than one machine it melting, there is something with the wiring where there circuit is being constantly powered.

+1

[hpwrick]

Peteski good to hear from you. 

Peteski, you wrote:  ""Actually, the way I see it, the machines were originally designed to work with the voltage supplied by the accessory terminal of all the standard 12V power packs (which have been in use probably even before even you were born).    Accessory terminals are normally powered directly from the secondary transformer winding which also (after being rectified) supplies the variable DC circuit. The secondary winding supplies between 16-20V to compensate for the losses caused by the rectifier needed to convert the AC to pulsing DC.  Makes sense?""

You won't mind if I disagree without being disagreeable.   Now how does one do that?

What makes sense is the 12 volt AC power supplies I purchased to power up the Atlas Switch Machines.    I never did like  hooking them up to the power supply that ran the trains.   When activating the blue slide switch it would draw down on the current available and cause the trains to slow, stutter or stop.    Depending on whether or not you were running them at slow...slow...realistic speeds.

I've not been happy with the Atlas Switches or their switch machines... from the get go and looked for better ways to set them up and wire them in.    Ahh...to little or no avail...other then using a 12 volt AC Power supply.    In any scale.

No offense meant toward Paul, as this is meant to be personal.   Atlas and I haven't seen eye to eye on a number  of things...over the years.

As I said before, my two cents and I take change.

[peteski]

Rick,
I'm not going to get into a pissing match with you again. I'm not saying that what you're doing it wrong. My gripe was with you stating "I've read here with some interest an authoritative discussion on how to solve these problems.    And, worry when newbies take a read considering what is written to be gospel.   As in newbies helping other newbies make the same mistakes.   While others, perhaps more experienced, make it almost to complicated...if you get my drift."

I tried to explain why Paul (from Atlas) stated that their switch machines are designed to be operated from voltages higher than 12V.  That's all. If they work for you at 12V then be happy.  But perhaps you shouldn't imply that the so-called experts and the actual rep from Atlas are wrong for recommending a higher voltage.  You really think that a capacitive discharge circuit is too complicated (even for newbies)? Well, StewRRFan is willing to give it a try.

[alhoop]

Rick
If you don't exceed the VA rating of the power pack then you can run trains and throw turnouts
with the accessory connection. I only use 1 Atlas turnout out of a few dozen but Atlas has made
great contributions to the hobby for which I am thankful.

Al