# A K-27 Question for Dinosaurs



## Dougald (Jan 2, 2008)

Recently, Tony Walsham announced that RCS would be shipping in late Feb a unit that plugs into the Ames socket on the K-27.  That would imply RCS compatibility with the wiring and the ability of the socket to carry the current which I believe has been set at 3A(?).

In the Jurassic Park thread, TOC has removed the Ames socket and other wiring too to install a current RCS product.  In the writeup, it was disclosed that a 6A unit was used because the motor stall current was measured at 3A.

Is the collective wisdom that the Ames socket is high enough capacity to handle the stall current?

Regards ... Doug


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## TonyWalsham (Jan 2, 2008)

Hi Doug.

I am going to build the PnP-3 for just such a purpose.
To be honest the prototype has yet to be tested because as yet I don't have a K-27 available to experiment on.
Stan Ames has assured us all that the socket pins can handle 3 amps.  That remains to be seen.
Provided the PnP-3 is capable of sustaining the current draw required it will be built.

Dave has removed the guts of the K-27 so that he can install the RCS system the way he desires.
My aim is to make the RCS installation as simple as possible.
If it does not work properly it will not be built and I will re-evaluate my approach.
I cannot fit the required components on the plug in PnP pcb to handle more than 3 amps.


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## Curmudgeon (Jan 11, 2008)

I did that unit for several reasons. 
One, the owner DEMANDED it be gutted. 
Two, I swore I would, and provide photos to show it. 
Three, I needed the space, and since I cannot guarantee the watertight integrity of said unit, the "gear" had to go where the Ames Super Socket went. 
We KNOW there MUST have been a reason they put the Ames Super Socket With Integrated Production Electronics where they did. 
My testing, outdoors, old aluminum track, locked drawbar, 2.5 to 3.0 amps, depending on how the drivers "bit" into the rails. 
A 3.0 amp throttle should be just fine, especially if their outputs are internally protected, but I thought I'd play it safe, as this unit goes outdoors. 
Next unit is for an indoor, more level layout. 
It will get a 3 amp unit. 

Oh, and on the opto triggers. 
Unless the large single digit number is supposed to be a part number or identifer, and the numbers are different for left and right (1, and 7, I think), there is NO identification of any type, eother manufacturer, or part number. 

What is the fall-back plan if yours fail? 
Where does one obtain the parts? 

Now, maybe there is only one in the whole world made that looks like that. 
All I would have to do is thumb through about 3,000 pages of catalogs and see if I can spot it.


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## Dougald (Jan 2, 2008)

thank you Dave and Tony for the quick response. 

I appreciate that there are many reasons why the factory installed wiring may be unsuitable - points ranging from inadequate tender space for battery/RC/sound gear to inadequate chuff triggers and so on. But if the Ames socket would not handle the current draw, then that would be a showstopper. 

I look forward tour test results Tony. We have seen at least in part, Roger Cutter's work with Airwire and if RCS can also find an install approach that uses the plug, I think it will help promote the use of battery/RC. In the end, getting all the features including big batteries for long run time may lead us to the Jurrasic Park solution. 

So far, I have held off buying a K-27 but when the dust settles, I think the Northland Railroad will have one or two in the roundhouse. Since there is no electricity trackside on the Northland, the control options are limited. 

Regards ... Doug


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## TonyWalsham (Jan 2, 2008)

Hi Doug.

As critical as I have been over certain aspects of the K-27, it does have a number of upsides.

Until & unless I find out otherwise, the Ames Super Socket looks like being designed pretty well much the way I requested it be during the discussions on the socket propoals at the end of Summer - Autumn/Fall in 2007.

The TRACK - BATTERY switch is wired correctly.
The BATTERY terminals are wired correctly.
The dummy pcb has built in motor "noise" suppression.
The socket pcb has the places to solder in screw terminals that parallel what the socket pins do.

Because the pcb in the K-27 is dated the 19th of September 2007 (Whilst I was virtually incommunicado in the UK ),  it means these features were already in place *before* I was asked to participate in the group discussion when I got back to Australia at the start of October.  So, I just simply don't understand why Mr Ames would keep telling me after Sep 19th that he could not get manufacturers to agree to the proposal.  Bachmann had already given me what I think was necessary on the socket and Mr Ames was saying manufacturers wouldn't do it.
Weird.  There must be some deeply concealed inner motivation hidden in that logic.

I have extensive experience using just such socket pins in RCS/EVO products.
I have stated all along that the maximum current I would care to subject the pins in the socket assembly to is about 3 amps at 15 volts.  About 45 va. That position has not changed.
The power IN pins on the K-27 are doubled up, so in theory they could carry handle 6 amps (90va).  That should be enough to handle the demands of the motor and the accompanying Bachmann electronics.
I already use gold plated pins, so, assuming the sockets into which the dummy pcb or the RCS/EVO PnP-3 controller will plug are the same, I see no problem using them reliably.  However, all this is subject to actual testing, and my opinion may change in the future.

Bachmann have listened with regards to one thing at least.  The K-27 runs smoothly with an adequate top speed using just 14.4 volts.  There is no need to use a higher voltage. In fact, if the batery voltage was higher the threshold of my va rating of the pins would be exceeded at maximum load.

Because overall I believe the K-27 is showing promise as to being an excellent loco, despite the mecahnical problems and the chuff timer issue, I believe it is my responsibility to at least try and advise Large Scalers how to install RCS/EVO battery R/C using the existing Bachmann electronics.  With no requirement for the consumer to add electronic parts to make the thing work correctly.   
Until I find anything to the contrary which may change my mind, that is going to be my approach.

Dave Goodson is taking another, perfectly valid approach.  
Dave and I do not always see eye to eye on how things should be done.


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## Curmudgeon (Jan 11, 2008)

That's 'cause ya see things upside-down. 
POME that you are.


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