Hornby Class 43 HST conversion

[Chrissaf]

As the dummy if motored will be running in reverse relative to the motor car, then to get the two to run together one of them will either need the motor wires reversing or an adjustment made to CV29. Remember also that the lights are back to front as well.

I replaced the single GoW bulbs in mine with a 3-legged red-white bi-colour led. Noting that you need a common anode type for DCC not the more easily found common cathode.

[Chrissaf]

As in swap the red and black wires, or the grey and orange wires?

.

All I'll add is that swapping the black and red wires will not make the slightest bit of difference to operation. The red and black wires carry a 'bi-polar' voltage signal which means that it is not sensitive to which way they are connected.

.

Personally, I wouldn't bother adding a motor. Lots of hassle for little gain. Plus, if the motors are not accurately matched, then the risk of derailment is increased.

.

When I convert it to DCC, can I assume that it needs two decoders if I want directional lights?

.

That would be the easiest option, else you would need to make an electrical wired connection from the motor car to the dummy motor care that traverses all the intermediate coaches as well.

[ColinB]

I actually added separate red and white leds, it looks more realistic, it does mean pulling out the lens, but on old locos they are usually a bit loose. I used tower leds they are smaller. For the resistors you can make it a bit easier by using a single in line commoned resistor pack (you can get them off EBay). For the dummy end, as you are only driving lights, I used one of those really cheap LaisDCC decoders. I don't know if you know but Peters spares was doing the later non powered bogies, with the extra pickups. Also I found the weight in the Dummy car wasn't needed, I removed it as it made the dummy car equivalent to about 3 extra coaches. Some of the later Virgin ones have 5 pole Ringfield motors. Hope it is of some use.

[Chrissaf]

OK, I've bought another Hornby class 43 with dummy car on DC. It has the grain of wheat bulb fitted at both ends. When I convert it to DCC, can I assume that it needs two decoders if I want directional lights? Also, if I'm putting a decoder into the dummy car, I might as well put a motor in it too. Would this have to be wired differently? As in swap the red and black wires, or the gray and orange wires? And should I 'consist' the two, or just give them the same decoder number? Thanks in advance. 

 

[96RAF]

I have settled on a standard resistor module for my lighting installs.

This is a simply a bit of vero mounting several 1K ohm SMD resistors connected to the leds fore and aft as shown.

Note how the red wires are crossed to maintain the directional logic of the lights (Front white/rear red and front red/rear white)

 

/media/tinymce_upload/3fe71d0e6d019ecee9aa30f2001169eb.jpg

 

/media/tinymce_upload/308f7507558714f1e1161728c2fcebbc.JPG

[ColinB]

blwtechnical services does a pcb version of this for £1.50 on EBAY + £0.99 P&P. They are 1 k pull up resistors.

https://www.ebay.co.uk/itm/DCC-LED-lighting-resistor-PCB-New-UK-stock/192653408416?hash=item2cdb09b8a0:g:KuAAAOSwzFxa4yNm

[96RAF]

Live linking is now possible Colin

https://www.ebay.co.uk/itm/DCC-LED-lighting-resistor-PCB-New-UK-stock/192653408416?hash=item2cdb09b8a0:g:KuAAAOSwzFxa4yNm

[ColinB]

RAF96 ok, thanks. I just assumed it altomatically did it with the paste function. I can see now it is a separate menu option.

[96RAF]

Sometimes it pastes in as an automatic link, other times it has to be hand cranked with the chain link. Something to do with it being a relative or an absolute URI.

[37lover]

RAF96

What size SMD are you using? The little research I've done suggests 0805 are 1/8 Watt rating and 1206 are 1/4 Watt. I've still got loads of axial resistors and I think they are 1/8 Watt but need to check. The SMD arrangement looks very need and I suspect will be more robust.

[ColinB]

If you work out the maths the wattage is 0.1 watt at 12 volts. So at 16 volts a 1/8 watt would be good enough. As I said in my post an SIL resistor pack or the ready made PCB work just great, I have used both. The same guy that does the SMD board also does a DCC socket board that contains a connector so you can wire the lights, such that you can disconnect the body electrics when you do a service.

[96RAF]

RAF96

What size SMD are you using? The little research I've done suggests 0805 are 1/8 Watt rating and 1206 are 1/4 Watt. I've still got loads of axial resistors and I think they are 1/8 Watt but need to check. The SMD arrangement looks very need and I suspect will be more robust.

 

Size 0603 - they are large enough to bridge adjacent tracks on verostrip board. Ideally a bespoke PCB would be neater and better but I don’t have the skills or kit to make one.

[Potrail2378]

Hi, just getting back to my original question - I have now fitted two Hornby decoders, one to the dummy car, and one to the power car. While I was soldering all this together, I put in cab lights (green wire) and guards' lights (purple wire) in each unit. I have tested both units, one at a time separately on the layout. My question now is - will both cab lights (and guard lights) come on together? If they do, which I think they will, do I give the dummy and power car separate addresses? But if I do that, will the direction lights work as they should? Would a consist help? Thanks. 

[ColinB]

Yes, they will come on together as they receive the same signal. If you give the dummy a different address they will be separate, as the dummy is not powered I don't think you need the consist, assuming you didn't put a motor in the dummy.

[Chrissaf]

If you think it about logically. Most real life consists involve two or more locomotives one behind the other but both facing forward in the same direction. Thus forward lights and rear facing lights will be the same on both. Personally, I don't feel that a consist decoder configuration is appropriate for this particuilar application.

.

However in a Class 43 HST scenario, the motor car at the rear (dummy in this case) will be facing the other way. Therefore you need to have the lights wired in reverse.

.

I suggest that you give both decoders the same DCC address so that you don't have to keep turning functions on and off as two separate sets of commands.

.

Now both decoders being configured with the same DCC address will receive a 'move forward' command (white decoder wire goes negative) or a 'move in reverse' command (yellow decoder wire goes negative).

.

So, on the front motor car you would wire the white wire to the white LEDs and the yellow wire to the red LEDs (if fitted) as normal. Whilst on the rear dummy car, the white and yellow wires would be reversed. Such that when the decoder in the dummy receives a move forward command, the white wire would be used for the red rear facing LEDs and the yellow wire would be used for the white LEDs. Thus when the front motor car is put into reverse, the rear facing white LEDs on the dummy motor car would then light up instead of the reds.

.

[96RAF]

To answer your other part of the question, the cab lights on F1 and guards lights on F2 will each respond in both cars in any direction if these share a common address which is convenient for directional lighting.

 

If you set separate addresses then you have to select both those addresses to get your lights as required, without setting up a consist. Some consists will allow you to individually control functions and some won’t i.e. both F1s say would usually light on selection in a simple consist, but in Railmaster it is the software that assembles and controls the consist so you can individually select F1 or F2 on either or both cars.

 

Your only other way out is to use a more sophisticated decoder which allows dependant function mapping and these decoders could be set to allow cab and/or guards lights to be directional controlled. I.e. dependant means if F0 fwd is selected then the power car cab and guards lights can be selected but these lights in the dummy car would only be enabled in F0 reverse. The Hornby decoders are not capable of this mapping.

[ColinB]

Next time you do it, this board looks quite interesting. I wish they were around when I converted mine. It cost me nearly this much for just the socket off Hornby.

https://www.ebay.co.uk/itm/HO-OO-Gauge-Directional-Light-LED-Distribution-Power-Board-Model-Train/254703455025?hash=item3b4d824b31:g:xJEAAOSw889eKKu2

[Potrail2378]

OK, what I'm thinking of doing next is to leave the green and purple wires where they are, remove the blue wires from each (cab light and guards light) and then take the live feed for these lights from the white wire in both the dummy and the power car. This will/should ensure that only the one cab/guard light will illuminate at once with the same address and using F1 or F2. For the small amount of time they will be illuminated, would the current be sufficient with a 4 amp PSU? 

[96RAF]

It won’t work...

Blue wire is a common positive, the other wires - white, yellow, green and purple are each switched negatives, so you can see if you use the directional lighting wires in attempt to power your aux wires they are all negatives.

 

The 4-amp PSU is not your limit for current - it is the decoder, most decoders will only supply a max of 100mA per function output and many are not self protecting on function outputs so any overload can damage the decoder.

[ColinB]

If you want to do this you need you can make a circuit with a pnp transistor driven by the blue wire and switched by green or purple wire, this then feeds the cab light and uses the white wire as the return. There are a few extra components you need, but is the general idea. I looked into this when I wanted to have independant lighting in a diesel. I think they do pnp transistors in dil ic packs so it could be a quite neat way to do both leds.

Oh I don't know if you already know this, the green and purple wires are what are called open collector circuits meaning that you have to pull them up with a resistor, normally this is the led and its feed resistor, but if you decide to use the pnp transistor you have connect a resistor (10 k) between it ( the base connection) and the blue wire.  

[Chrissaf]

For the small amount of time they will be illuminated, would the current be sufficient with a 4 amp PSU?

.

Grain of wheat bulbs can easily be replaced with 3mm round LEDs.

.

Assuming each LED is fed via a 1,000 ohm resistor. If you don't include the resistor the LEDs will burn out instantly. Then the current that each LED draws will be in the region of 10mA [0.01 Amps]. Insignificant compared to the 4 Amp supply.

[Potrail2378]

Thanks for all the info and your time in helping me out with this project. I used to work as a quality auditor for IBM computers - circuit board management, so am more than happy to take your advice and put it to good use. I have one more question though - if I wanted to just have the power and dummy cars running together, what coupling is available? They are currently fitted with S9695 (?) with two tanks, but no hooks. Must I use at least one carriage between them? Thanks in advance. 

[ColinB]

If you go the pnp transistor route there is a dual pnp pack called BC847BPN. You can get them off ebay, I didn't check the size but I assume they are quite small. I think I might try this on my diesel cab lights.