How Many Decoder Pins Do I Need?

[Suzie]

Unless you make your own the function decoders do tend to be more expensive. As it happens there is room in the roof of a 170 for a home made 8-output function decoder, I have done it, and Bachmann very kindly supply a plug and socket between the body and the chassis so that you can plug  it in.

 

I think you will just have to bite the bullet and put one decoder in each end.

 

The Express Models kit only requires 3-functions if you are clever - head day, head night and tail. So if you remap the functions on your decoder (Zimo is quite flexible in how you do it, others may be less so) you can free up a function output for the door open lights!

[Sir TophamHatt]

OoOoOo - do you have any further details on how you did the decoder or how to get my hands on a cable?

[Suzie]

Instructions for making the DIY decoders are on the DIY Decoder website:-

 

http://dccdiy.org.uk

 

There is some specific information about connecting the the lights in the 170 on the applications page but that does require swapping round the red LEDs if you want automatic parking lights (red lights on both ends when stabled controlled by F0 being off) and you just use a spare output for the door lights:-

 

http://dccdiy.org.uk/application.html

 

You recover the connector from the old lighting unit when you remove it.

[Julia]

Ha ha, it's only a 2-car train.

I did look at "function only" decoders but the one I saw was more expensive than the Lenz Standard + v2 anyway.

 

This is the case with a lot of the decoders, but the Digikeys DR80015 2 function decoder is both the most compact function only decoder (tho still bigger than some motor decoders), and can be had for €12-15 if you shop around. They also make one with more outputs, but I've not seen a price for it. 

 

I've just built myself a 17 function, function only decoder based on an Arduino Pro Mini. It's very flexible, but a long way short of being compact enough to fit in a loco, or even most carriages. I built it for static use (but using the mobile decoder address space and functionality). 

 

J

[Julia]

Don't worry - you can talk to me in as much simple and child-like way as you like.  I know very little about DCC

 

Would the Lenz Standard + v2 controller work for the Express Models lights? (they come with 4 function outputs as far as I am aware).

 

And would fitting a resistor make the lights dimmer then?  I wouldn't know where to buy one :/  I guess I'd have to buy 100 for a few pounds from somewhere like ScrewFix?

 

Resisters aren't going to be something you pick up from screwfix, but you can get them from Maplin. Maplin would be far from cheapest. Other options are ebay. Often the cost of postage will be higher than the cost of the resisters. If it wasn't for the fact I've just run out of most values, I'd stick a couple of dozen 560ohm and 1k resisters in an envelope for you (if you're in no rush, I can do this in a couple of weeks when I restock). 

 

Sorry to drag this up again.

 

So just to make sure - I can fit a socket, which is a standard size, then upgrade the chip in it to be 4, 8, 21 sockets in the future if I need more?

 

I am looking to convert around 10 trains, all uni-formally if possible (not really possible, but I can hope!), so all the trains have about the same features and stuff.

 

If you're fitting sockets, an 8 pin is most likely to be the most universal choice there. Unless you have a loco with lots of lighting, sound and other functions, you're not going to have much need for a 21 pin decoder. 

 

J