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Help with a circuit diagram and decoder choice.


rynd2it
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I'm looking for a DCC decoder that will fit in my 009 Roco shunter (see other thread) and will provide motor and front/rear light functions. There isn't much room so it will need to be hard wired, no space for a socket.

 

This loco has space to put a head light and a tail light so I was thinking of a dual colour LED of red/white and wiring it so the head light is white and the tail light red when going forward, the opposite in reverse. However my research into bi-colour LEDs shows them with only two pins - how does this work or integrate into this diagram taken from the Laisdcc manual?

 

 

 

 

 

DCC_chip.jpg

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Zimo MX617F from CoastalDCC -  it is 6 pin with the 7th blue wire floating, Cut off the 6 pin interface to wire it into the loco, you will also need to add in resistors to stop the LEDs blowing up :)

 

£20 - £21.50 inc postage.

Edited by WIMorrison
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If they are two pin then they must rely on reversing polarity to change colour so it looks like they are  fundamentally incompatible with the wring diagram.   Three wire ones should be OK as they have one common connection but I have never seen a red / white, all mine have been Red/Green with a yellow available by lighting red and green simultaneously.

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13 hours ago, DCB said:

If they are two pin then they must rely on reversing polarity to change colour so it looks like they are  fundamentally incompatible with the wring diagram.   Three wire ones should be OK as they have one common connection but I have never seen a red / white, all mine have been Red/Green with a yellow available by lighting red and green simultaneously.

These might work but I'm noticing they have a positive common - is that a problem?

https://www.dccconcepts.com/product/led-tower-type-dual-colour-6x-2mm-wresistors-prototype-whitered/

 

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18 hours ago, WIMorrison said:

Zimo MX617F from CoastalDCC -  it is 6 pin with the 7th blue wire floating, Cut off the 6 pin interface to wire it into the loco, you will also need to add in resistors to stop the LEDs blowing up :)

 

£20 - £21.50 inc postage.

Is there an alternative to this such as a LaisDcc version? The postage to France is horrific and the only supplier in France I can find wants €40 inc postage.

 

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22 minutes ago, rynd2it said:

Is there an alternative to this such as a LaisDcc version? The postage to France is horrific and the only supplier in France I can find wants €40 inc postage.

 

 

There will be dozens of EU model suppliers who offer Zimo products.   Most will be in Germany, Austria, Netherlands.   Most ship to other EU countries without hassle.  

 

Zimo are one of the very best decoder's you can buy.  

 

 

- Nigel

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I would have thought so too - but searching for them is only turning up a couple and the prices are outrageous or the postage is. And another problem common to many EU on-line retailers is that they don't tell you what the postage is until you have created an account.  I'll keep looking though

 

Edited by rynd2it
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16 minutes ago, rynd2it said:

Thanks Ian, There's a load there however, I just went through all the French ones - only 1 had it in stock at €37 + €22 postage!!!!  This is going to take a while

 

 

I don't understand why the French supplier is overcharging on the item and the postage, and why none have any in stock, look at the German suppliers as their postage around EU tends by reasonable

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2 minutes ago, WIMorrison said:

 

I don't understand why the French supplier is overcharging on the item and the postage, and why none have any in stock, look at the German suppliers as their postage around EU tends by reasonable

Stuff in France is usually more expensive than the UK, its not just on modelling, clothes are really expensive as well. Just comparing the same item on Amazon UK to Amazon.fr shows up some outrageous over charging. I will start on the German ones soon

 

Thanks for all the help with this

 

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If using 3-pin bi-colour leds on DCC they must be common anode.

The blue wire of an 8-pin decoder connects to the anodes and the colour legs (cathodes) are connected via suitable value resistors to the directional white and yellow wires which are switched negatives.

I have used 3-pin red/white and red/yellow leds. Easy enough to find in various sizes.

Edited by RAF96
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22 minutes ago, RAF96 said:

If using 3-pin bi-colour leds on DCC they must be common anode.

The blue wire of an 8-pin decoder connects to the anodes and the colour legs (cathodes) are connected via suitable value resistors to the directional white and yellow wires which are switched negatives.

I have used 3-pin red/white and red/yellow leds. Easy enough to find in various sizes.

That's very helpful, thank you

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1 hour ago, RAF96 said:

If using 3-pin bi-colour leds on DCC they must be common anode.

The blue wire of an 8-pin decoder connects to the anodes and the colour legs (cathodes) are connected via suitable value resistors to the directional white and yellow wires which are switched negatives.

I have used 3-pin red/white and red/yellow leds. Easy enough to find in various sizes.

Looks like a goer then.  The ones referenced above have one resistor per LED in the common wire but good practice is to have two one so you can vary the relative intensity anyway with one resistors the wiring looks like this.

How come the French want twenty quid postage when the Chinese want 99p?   Answers on a five quid note to...

Screenshot (489).png

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I would strongly advise against the single resistor solution as you will either have a very bright red light and a normal white light, or a normal red light and a very dim white light.

 

how do I know? Because I tried single resistors and have had to revise to using 2 resistors.

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I put a 1k ohm resistor in all three legs of each led to tame the brightness and semi-balance the colours.

It looks from your amended diagram that you have taken note that you need the white wire connected to the white front led and back red led and vice versa for the yellow wire to the front red led and rear white led. This is where balancing the colours buy use of more exact resistor values comes in. 

To aid installation I make up a small veroboard with smd resistors to which the DCC socket wires and leds extension wires connect to.

 

84AC0563-235A-4920-B51A-20E1C0DF9D73.jpeg

Edited by RAF96
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On 04/11/2021 at 10:59, rynd2it said:

Is there an alternative to this such as a LaisDcc version? The postage to France is horrific and the only supplier in France I can find wants €40 inc postage.

 

Well, after a long search, I went back the Coastal (they were out of stock yesterday) and lo & behold, back in stock, sensible price (VAT free) and very sensible postage - ordered two, sorted. 

 

Thanks all

 

 

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6 minutes ago, rynd2it said:

Well, after a long search, I went back the Coastal (they were out of stock yesterday) and lo & behold, back in stock, sensible price (VAT free) and very sensible postage - ordered two, sorted. 

 

Thanks all

 

Its correct that an export from the UK is free of (UK) VAT.   But, I think they should be (European) VAT charged on entry to the EU.... 

 

- Nigel

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11 minutes ago, Nigelcliffe said:

 

Its correct that an export from the UK is free of (UK) VAT.   But, I think they should be (European) VAT charged on entry to the EU.... 

 

- Nigel

Yes it is correct but many UK retailers are charging VAT and then adding the CN22 customs form so I end up paying VAT twice, plus customs duties. Its a real mess at the moment and don't get me started on eBays Global Shipping Program, a real rip-off

 

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On 04/11/2021 at 12:01, RAF96 said:

If using 3-pin bi-colour leds on DCC they must be common anode.

The blue wire of an 8-pin decoder connects to the anodes and the colour legs (cathodes) are connected via suitable value resistors to the directional white and yellow wires which are switched negatives.

I have used 3-pin red/white and red/yellow leds. Easy enough to find in various sizes.

 

For bi colour try these from express models.

 

https://www.expressmodels.co.uk/catalogue/the-led-store/2mm-red-warmwhite-bi-colour-lighthouse-for-dcc-common-10-units-detail

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