Re-wiring Bachmann K-27, cooling fan question

Posted By steam5 on 12/29/2008 9:09 PM
In another post I asked about the fan sucking the smoke back into the boiler of my K-27. The solution is turning the fan around.

http://www.mylargescale.com/Community/Forums/tabid/56/forumid/14/tpage/1/view/topic/postid/69995/Default.aspx#70516

It appears this is a cooling fan and probably should be kept. When I re-wire the loco (I currently plan to remove most of the electronics) I will remove the smoke unit, should I still keep the fan installed for cooling?

When I install the DCC decoder, how have others wired the cooling fan up? Parallel with the motor, or power it from a DCC function output?


I provided some suggestions to Bachmann when they developed the Ks electronics so I am familiar with whats inside and therefore may be able to help you with your modifications.

The K27s electronics are totally isolated from the tracks and the fan is powered from DC provided through the device plugged into the socket. The fan is likely very important if the motor is under load for extended periods but also likely not of much need for normal light running.


If the noise of the fan is something you want to remove then I would suggest adding a low value thermistor attached directly to the motor. SInce most common thermistors are break rather then make in the presence of heat you would also need a relay so that if the motor heats up the fan turns on.

If you tell us what effects you would like to be different from the stock locomotive some of us may be able to suggest changes to the existing wiring to accomplish these changes.

Stan
http://www.tttrains.com/largescale/

Posted By StanleyAmes on 12/30/2008 5:26 AM
Posted By steam5 on 12/29/2008 9:09 PM
In another post I asked about the fan sucking the smoke back into the boiler of my K-27. The solution is turning the fan around.

http://www.mylargescale.com/Community/Forums/tabid/56/forumid/14/tpage/1/view/topic/postid/69995/Default.aspx#70516

It appears this is a cooling fan and probably should be kept. When I re-wire the loco (I currently plan to remove most of the electronics) I will remove the smoke unit, should I still keep the fan installed for cooling?

When I install the DCC decoder, how have others wired the cooling fan up? Parallel with the motor, or power it from a DCC function output?


I provided some suggestions to Bachmann when they developed the Ks electronics so I am familiar with whats inside and therefore may be able to help you with your modifications.

The K27s electronics are totally isolated from the tracks and the fan is powered from DC provided through the device plugged into the socket. The fan is likely very important if the motor is under load for extended periods but also likely not of much need for normal light running.


If the noise of the fan is something you want to remove then I would suggest adding a low value thermistor attached directly to the motor. SInce most common thermistors are break rather then make in the presence of heat you would also need a relay so that if the motor heats up the fan turns on.

If you tell us what effects you would like to be different from the stock locomotive some of us may be able to suggest changes to the existing wiring to accomplish these changes.

Stan
http://www.tttrains.com/largescale/



This is too good to not archive.
Plug and Pray, redux.

Posted By steam5 on 12/30/2008 6:22 PM
Greg, I agree about you point on paralleling the fan with the motor, it was just a simply nasty solution But I do think there would be more electrical issues with that solution, due to different current draws.


Stan, The noise does not bother me; I don’t think I will hear it over the phoenix sound board when I install it. Where would you get the power from to power the fan? If you leave all the Bachmann electronics how does the fan behave under DCC operation?

I guess ideally I would like the fan to come on automatically when the motor starts to turn. I don’t think this behaviour can be programmed to a DCC function output?

If (motorTurning = true){
Fan = ON}

Else{
Fan = OFF}


At worst the fan sounds like an electrical steam generator and is masked by the phoenix sound. Unless you have a specific change you wish to make I would leave the electronics as they are. The locomotive's electronics need DC to operate. This DC is normally provided by whatever you choose to plug into the socket. So if Power on/ Fan on. There is no connection between the fan and the motor.

You can switch on and off the internal electronics (including the fan) by hooking up the locomotive's "-" wire to a function output. You can use the same function output to turn on and off the sound so that when the locomotive is not in service everything is off and when you want to fire it up you turn on the elecronics and sound.(which includes the fan)

To do what you desire (connecting the fan operations to the motors operation) you would need a mechanical or electrical sensor on the motor that would connect the - line when turning.

I think either leaving it as it is or using the function control of the "-" line is a simpler solution.

The downside of using a function is that most current decoders (including the phoenix) only support F1-F12 and you quickly consume all 12. As the manufacturers start supporting all 27 functions this option becomes much more viable.

Stan
http://www.tttrains.com/largescale/

Happy New Year

Stan my reasoning for re wiring the loco is I find myself changing items and it has always been easier for me to just start from scratch. I use this philosophy for all my HO installations, and I carried it to my first large scale installation (Spectrum 2-8-0) and it worked, the K will be my second.

Please don’t be offended, as I do it to nearly all my locos. I feel bad when I re build things, as someone put a lot of effort into it.

Greg that’s exactly what I was thinking. If I map an output to F0 (head light) the fan will run whenever the head light on. Not exactly what I want but it’s a compromise, it will keep it compliant with the KISS method, a temperature controlled unit would be nice, but it’s not KISS.

The Lenz Maxi can handle 1A for the total of all function outputs. If I go over this limit I think I will use one of the switches present in the front of the boiler, some will be free as I plan to by pass some. And to power it I will just make a simply bridge rectifier to get DC and filter it with a regulator and capacitors, I may be able to utilise the Bachman circuit, but I won’t know until I see what it is.