WIRING COBALT MOTOR AND ELECTROFROG POINTS

[PaulWarb]

Hi

 

Someone is going to be very brave to take on a response to what follows!!   I have a relatively new DCC layout - positioned most of the track and points and electrified the layout - all working well.  I have an NCE Powerpro.    

 

I am at the stage where I am thinking about a control panel and wiring up point motors etc.    For the moment I have decided to use Cobalt point motors -  I have bought one and it is working well on a point with a 9V adapter.   I have also dabbled with wiring up some green and red LEDs and an SPDT switch for the control panel with the same 9V adapter - this is also working.   I am reasonably confident then that I can change the point motor and have LED indicators working on a control panel - great so far.  

 

Now comes the problem.  I can't see what to do with the wire that changes the frog polarity.    Websites seem to say to link the dropper wire from the point motor to a common terminal / frog polarity switch on the Cobalt.   Doesn't this mean though that the track power - from the bus - must also feed the point motor and that the point motor then changes the polarity at the frog end of the point as the direction is changed?   I have seen others say that there is a problem here as the power from the bus / NCE is too high for the Cobalt and creates problems - as said it is working perfectly with the 9V supply.   I'd also then be separating control of the leds from the switching of the point motor i.e. two separate power supplies and circuits.  Are there any solutions to this?

 

One further point - it seems that all this effort is simply to get the frog end of the point electrified and the polarity switchable so as i) not to cause a short and ii) to allow for very smooth and consistent running.  At the moment of course the frog end of my points is not electrified BUT - my locos run over the point perfectly well without this - I presume picking up power still from one set of wheels on the other end of the point.  I am thinking that if this works as smoothly as it does why I am I agonising with sorting out this frog problem.   

 

I'll be very grateful for any help.

[Lady_Ava_Hay]

Hi

 

Someone is going to be very brave to take on a response to what follows!!   I have a relatively new DCC layout - positioned most of the track and points and electrified the layout - all working well.  I have an NCE Powerpro.    

 

I am at the stage where I am thinking about a control panel and wiring up point motors etc.    For the moment I have decided to use Cobalt point motors -  I have bought one and it is working well on a point with a 9V adapter.   I have also dabbled with wiring up some green and red LEDs and an SPDT switch for the control panel with the same 9V adapter - this is also working.   I am reasonably confident then that I can change the point motor and have LED indicators working on a control panel - great so far.  

 

Now comes the problem.  I can't see what to do with the wire that changes the frog polarity.    Websites seem to say to link the dropper wire from the point motor to a common terminal / frog polarity switch on the Cobalt.   Doesn't this mean though that the track power - from the bus - must also feed the point motor and that the point motor then changes the polarity at the frog end of the point as the direction is changed?   I have seen others say that there is a problem here as the power from the bus / NCE is too high for the Cobalt and creates problems - as said it is working perfectly with the 9V supply.   I'd also then be separating control of the leds from the switching of the point motor i.e. two separate power supplies and circuits.  Are there any solutions to this?

 

One further point - it seems that all this effort is simply to get the frog end of the point electrified and the polarity switchable so as i) not to cause a short and ii) to allow for very smooth and consistent running.  At the moment of course the frog end of my points is not electrified BUT - my locos run over the point perfectly well without this - I presume picking up power still from one set of wheels on the other end of the point.  I am thinking that if this works as smoothly as it does why I am I agonising with sorting out this frog problem.   

 

I'll be very grateful for any help.

 

Try here. My experience of Richard Johnson the proprietor of DCC Concepts is that his website is very informative and well described and laid out. If you are still stuck, I think he runs a profile on here.

 

http://www.dccconcepts.com/vamr/overview-and-wiring-for-all-cobalt-models

[Jeff Smith]

Are you using unmodified electrofrog Peco points with rail insulators on the frog rails? If so, the point rails act as the frog switch by contact with the stock rails. However this contact can be unreliable so establishing frog switching via the point motor microswitches is the best way to go. Frog switching is for rail power and is independent of the point motor power.

[PaulWarb]

Are you using unmodified electrofrog Peco points with rail insulators on the frog rails? If so, the point rails act as the frog switch by contact with the stock rails. However this contact can be unreliable so establishing frog switching via the point motor microswitches is the best way to go. Frog switching is for rail power and is independent of the point motor power.

Hi Jeff

 

Thanks for your reply. 

 

The point I have been using for my tests has been modified in the usual way for DCC. 

 

Frog switching is for rail power and is independent of the point motor power.

 

I'm not very electrically savvy sorry - are you saying that I can power my point motor with the 9V adapter and link a common terminal on the cobalt to the dropper wire on the point motor to change the polarity?   I can't see how the power from the bus is getting to the frog end of the point.

[Paul W]

Hi Paul

 

The main consideration you need to make is whether you intend to run short wheel base locomotives. e.g. 0-6-0 shunters over your points, as these will definitely stall on points where there is no feed to the frog end. Even some larger wheel base loco's will also be prone to stalling as not all wheels are used as pick-ups on both bogies, and there will be times when the pick ups are not working 100 % anyway and stuttering or stalling will be the result. Even some of the Bo-Bo types of loco's will have trouble on some of the longer radius points which are not fed at the frog end as the isolated section will be greater.

 

I can't offer any advice concerning the cobalt type of point motor as I have no experience of these, but I would always recommend a feed to the frog end of any point to allow for smoother running, especially if planning to have DCC Sound, as you never know what your future loco purchases could be.

 

I don't know which type or code of track you are using but with Peco code 100 or code 75 finescale track it is easy to install Seep PM1 point motors which have the polarity switch already included in the PCB, but the obvious disadvantage of this solenoid type of motor is the force in the throw of the point blade which can in time lead to a points failure, but in my experience with over  several 100 such installations over the last 20 years, I have only had a handful of failures, and these were at heavy use areas on layouts.

 

Hope this helps a bit. I am sure someone with experience of the Cobalt motors will be able to help further.

[Lady_Ava_Hay]

Hi Jeff

 

Thanks for your reply. 

 

The point I have been using for my tests has been modified in the usual way for DCC. 

 

Frog switching is for rail power and is independent of the point motor power.

 

I'm not very electrically savvy sorry - are you saying that I can power my point motor with the 9V adapter and link a common terminal on the cobalt to the dropper wire on the point motor to change the polarity?   I can't see how the power from the bus is getting to the frog end of the point.

 

The power to the frog is dictated by the point motor. Just solder a wire to the frog and use the requisite terminal on the Cobalt

 

 

[Steven B]

At the moment you're using pins 1 and 8 (the outside two) to control the point motor using your 9V supply.

 

The other 6 pins of the motor are a pair of SPDT switches. You can use these to provide power to the frog of your point. Connect the track feeds to what DCC Concepts call the "Left" and "Right" contacts of one of the switches, and connect the associated "common" to the frog of your point. When the motor throws the point it will also switch the polarity of the frog (you'll need to make sure you connect the Rail A/Rail B feeds to the correct "Left"/"Right" switch input - do it at random and you'll have a 50% chance of making a short).

 

Switching the power to the frog using the point motor isn't absolutely necessary. As you've discovered you're running quite happily relying on the point blades to switch power. However, providing a switched power feed to the frog will mean that you're less reliant on clean track and point blades to maintain reliable running.

 

Happy modelling.

 

Steven B.

[Nigelcliffe]

For the moment I have decided to use Cobalt point motors -  I have bought one and it is working well on a point with a 9V adapter.

Are these the basic Cobalt motor, not the "Digital Cobalt" ones with the inbuilt DCC decoder ?

If you have the "basic", that's good as they work like everyone expects a decent motor to work.

 

The Digital Cobalt model has a few quirks (some may describe them as mistakes) in its design.

 

 

Now comes the problem.  I can't see what to do with the wire that changes the frog polarity.    Websites seem to say to link the dropper wire from the point motor to a common terminal / frog polarity switch on the Cobalt.   Doesn't this mean though that the track power - from the bus - must also feed the point motor and that the point motor then changes the polarity at the frog end of the point as the direction is changed?   I have seen others say that there is a problem here as the power from the bus / NCE is too high for the Cobalt and creates problems - as said it is working perfectly with the 9V supply.   I'd also then be separating control of the leds from the switching of the point motor i.e. two separate power supplies and circuits.  Are there any solutions to this?

 

The basic Cobalt has Eight terminal connections on it.

Two are the motor drive, reverse the DC power and the motor goes the other way (as you've found with your 9V supply).

The remaining six terminals are two change-over switches, which change as the motor moves (each is labelled "Left, Right, Common"). Use one of these to switch the crossing(frog) polarity: attach the frog to the "common" on the switch, and the two DCC track feeds to the corresponding L and R terminals. As the Cobalt moves from left to right, the switch will change to decide which of the two DCC track feeds to use for the frog. If you get it wrong and the turnout shorts, then reverse the two DCC wires to the L and R.

 

LEDs for direction indication can be done a number of ways. Do you want the LEDs on the control panel beside the switches, or on the layout near the turnouts ? Depending on which there are easier (and harder) ways with more or less wiring.

 

 

[gwrman]

Hi I've always used a DPDT switch wired to reverse the polarity when thrown the other way as shown in this picture from the DCC Concepts site.

 

 

Nigel 8)

 

 

[PaulWarb]

Hi

 

Thanks to everyone for all the advice and help.  I have also rung Gaugemaster and spoken with very helpful gent (Pat).  You will probably think I'm very thick - I was missing a couple of wires to terminals 2 and 3 from the power feeds.  I now have power at the frog end of the point and fairly confident that I can get this working correctly.   I might add a wiring diagram here at a later date once it's all working that might help others with the same problem.  I couldn't find anything on the internet that showed me the overall solution - just bits of a jigsaw here and there.   All your advice helped me towards the solution.  Thanks again.

 

I hadn't found this before and found it a useful overview of the terminals on the basic Cobalt point motor. 

 

http://www.dccconcepts.com/vamr/overview-and-wiring-for-all-cobalt-models