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DCC Function decoders


Julia

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I am looking for a very small, affordable DCC function decoder that I can install in my coaches to control their lighting. It only really needs to be a single function to drive some white LED's. Unfortunately it seems that all the function decoders I can find are very large, that is except for some DIY designs I have found, such as those from http://www.g-zi.de/

 

Before I start looking at the DIY kit, can anyone think of an off the shelf solution I am missing?

 

Thanks

 

J

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Digitrax' basic transponding decoder might be small enough. Or the Bachmann N gauge 6-pin loco decoder can be fairly cheap and is small. Its often the case that a loco decoder is cheaper than a function only decoder.

 

For DIY, the easiest to follow is probably Paul Harman's design, it could be made smaller by using surface mount parts rather than wired ones.

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The TCS ones are fairly small- FL2 and FL4's, and are about the same size as normal N gauge decoders.

 

James

 

They are still way to big. The George Ziegler one is about 11mm square, which is over half the size of the TCS FL2.

 

Would using a 2 function loco decoder in a device without a motor cause issues?

 

J

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Motor decoder as a function decoder should be fine. The only snag is you won't get an acknowledgement when programming it, but that is also true of most function decoders.

 

Zimo's smallest function decoder is 12mm by 8.5mm by 2.2mm, same size as their smallest motor decoder, but I'm not sure if that one has been released yet.

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They are still way to big. The George Ziegler one is about 11mm square, which is over half the size of the TCS FL2.

 

Would using a 2 function loco decoder in a device without a motor cause issues?

 

J

 

I use basic N/Z scale Digitrax decoders as my function decoders in DMU trailes and the like. There is no problem with running a standard decoder with no motor except the programming 'issue' mentioned above.

 

Adrian

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What scale Julia?

 

If HO/00 surely a TCS FL2 would fit.. Sze 20x12x2mm.

 

Also there is the TCS Z2 2function normal motor decoder size 13x7x2mm. Z2 is 1amp current draw.

 

Fitting a100ohm resitor across the motor (orange/grey) wires on the standard motor decoder should allow programing.

 

Have done it many times with various decoders. The resistor can be left in place just don't op the throttle.

 

If there is a fear of accidental throttle op just put a value of zero ( 0 ) in all CVs From 67 thru 94 and add value of 16 to CV29.

 

I must admit there is three makes of dedcoders I will not have a bar of. Being, Hornby, Bachman, Digitrax.

 

Cheers

 

Ian

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Ian's comment about the resister allowing standard programming is also the information TCS suppy with their function only decoders, and also to remove for use. In fact, a friend found that this also works with Tsunami if you only want a sound dummy. If you only want to run leds, i would have thought the cheapest most basic n/z scale would suffice.

Matthew

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Putting a resistor across the motor leads doesn't 'allow programming', it allows feedback during programming. The programming should occur regardless of whether there is a resistor or not. In the Tsunami case, some of the sound response is load-based, so it may actually be necessary to have a resistor to have things happen mostly as you want (it won't be perfect because sone of the features of a Tsunami can be based on back-emf, which you won't get from a resistor).

 

Adrian

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What scale Julia?

 

If HO/00 surely a TCS FL2 would fit.. Sze 20x12x2mm.

 

I am modelling in H0e, so I don't have the space that H0/OO has. I could just about squeaze 20x12x2 in, but the site I found info on the TCS FL2 listed it as being 25mm long, which is too long.

 

Also there is the TCS Z2 2function normal motor decoder size 13x7x2mm. Z2 is 1amp current draw.

 

 

That is a more suitable size.

 

Thanks

 

J

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I use two methods of programming cheep loco decoders as function only use.

 

One way is to plug the decoder into a loco with the equivalent socket, program the decoder then put it inthe rolling stock you got it for. Not so easy if you have to hard wire one but still doable.

 

The other way is to use an ESU decoder tester board which has a motor a speaker LED s for the functions and various types of decoder sockets such as 21 pin, 6 pin 8 pin and clips for hard wired decoders. Costs about £35 but I have found it extremely useful.

 

Ian

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