Flickering Fire Box Princess Royal Class

[Dave1700]

I have just purchased a R3999 Princess Royal Class and fitted a TTS decoder, the flickering fire box appears to be static and when the loco is on the track But not in use the firebox glow is still on (ie i have deselected it from the throttle). My question is how do i switch the glow on and off

so it is off when not in use and on when it is in use.

Any help would be appriciated

Davidsleeping

[96RAF]

If it is connected to the green function wire then on a steamer it is F18 or F25 on a diesel. What does the loco manual say.

[ColinB]

The flickering firebox runs all the time and is not controlled by DCC. The firebox is in the loco whereas the DCC decoder is in the tender, so there is no way to drive it by the decoder. The device itself is just a couple of diodes connected to a led, which in the case of DCC just picks up the raw DCC signal to light. So as long as you have DCC connected to the track, it should be illuminated. Peter's Spares were doing the raw part which I fitted to a few of my old locos. So basically there is no control the only way to switch it off is to turn off the DCC. That is why you will notice on the Bachmann V2, they moved the decoder from the tender to the loco because that is the only way they could control the fireglow via DCC. To be quite honest I don't know why they bothered you can hardly see it.

[81F]

I would also add that I have been told that in the days of steam, loco's were often kept warm for most of the time, So there might well have been some firebox glow unless the fire was being dropped for cleaning/servicing so it might not be too unauthentic to have the firebox glow on while your loco is stationary when it is not on shed.

[96RAF]

You would only see it when the firebox door was open now and then to shovel more coal in so a bit of a gimmick in my opinion. I would rather see those cumulative pennies spent on standardisation of parts like the motor.

[ColinB]

I agree 98RAF, but it is not as bad as the opening doors on a HST. You know that if you open them too often they will fall off. On some of the Bachmann and Dapol locos it only comes on when you shovel the coal which is quite good but that means you have to have the decoder in the loco. Trouble is on the V2 you can hardly see it and on the Dapol Mogul I read the YouChoos review which said adding a bit of silver paper in the right place helped a lot. As to the motors, I don't think that would actually cost anymore, if anything it would probably save them money, I can understand on some models they have to be different. The same with con rod bolts and tender wheel axles. The other thing is tender bottoms between Railroad and fine detail A1/A3s the mounting arrangement for screwing down the tender top is in a different place, so you need at least two types of tender bottom. It would be cheaper to just depopulate it and use the same one for both. Funny Bachmann redesigned the V2 and came out with a model that actually is not that great mechanically (try taking the loco body off) although it looks good. I must admit though I do like the firebox glow on any loco.

[Dave1700]

Thanks for all your replies

You have been most helpful and as I am new to DCC I now fully understand why it is on all the time

If it is AC or DC I know it inside out but I do confess DCC is rather baffling especially as you can't use the good old multi meter

[ColinB]

You can use the multimeter, you just have to select AC. The only big issue I recently had was working out if the polarity of of the signal was correct. Although my layout is DCC I have lots of sections so I can switch the DCC off on a particular section, mainly for fault finding. I inadvertently got one of the sections polarities round the wrong way, finding it on AC is impossible, so I powered it with DC so I could check out the polarities of the various feeds.

[96RAF]

Apologies for wandering off topic but in response to previous comments...

@ Dave

DCC is a form of AC but not sinusoidal per house mains. It is a bi-polar square wave of about +/-15volts about 0. The square wave appears pulse modulated but is in fact a binary signal is made up of zero bits and one bits, each a specific length per NMRA regs. The arrangement of these bits translates to specific commands to the track, hence locos and accessories.

@Colin

There is a Noddy way of establishing phase that I used on my old turntable wiring. All it does is ensure the A and B connections are matched if the table bed has been turned past 180.

A red - green led is fitted at each end of the table bed one of which was lit green and the other lit red until switched over by a DPDT switch to red - green. If the green led was lit at the layout end of the table you knew it was safe to drive on/off else switch the table bed phasing to suit.

See here -

[VESPA]

All these little add ons to the latest models, add greatly to the price. The firebox door was more often part open or shut on the move and they are not that wide either. I fail to see why the feature is there at all. We had glowing fireboxes some years back and synchrosmoke. No doubt we will be getting cylinder draincocks working along with sequential safety valves lifting next. All for an increase in price of a mere £300 per loco. It is becoming cheaper to collect classic cars.

[Jim-R855]

All these little add ons to the latest models, add greatly to the price. The firebox door was more often part open or shut on the move and they are not that wide either. I fail to see why the feature is there at all. We had glowing fireboxes some years back and synchrosmoke. No doubt we will be getting cylinder draincocks working along with sequential safety valves lifting next. All for an increase in price of a mere £300 per loco. It is becoming cheaper to collect classic cars.

 

 

Who wouldn't love live steam in OO guage? Powered by some kind of carbon free fuel obviously.

I have to admit that I wrestled with the concept of firebox glow and whether firebox doors spend enough time open to make it worthwhile, and in the end decided that since most of my decoders have a green wire doing nothing else and the DCC concepts nano LEDs take up incredibly little space (the challenge can be finding space for the resistor), just to add it to all my locos. I also added working loco lamps for headcodes and tail and side lights to my brake vans, all of which are virtually invisible unless you have the lights down to simulate evening or night time operations, at which time a bit of an orange glow coming from the cab does seem right to me. I use Railmaster so could quite easily reprogram the macro for the coal shovelling sound (where I have sound) to also turn the firebox glow on and off so it is only on when stoking, but haven't.

Personally there are some features I would prefer to add myself - firebox glow, smoke generator, working loco lamps, coach lighting, brake coach lighting, brake van lighting. I can't see the point of magnetically activated coach lighting when I can fit an ESU lighting strip with built in DCC decoder for about the same as the price difference, and then I can control the lighting on an entire rake from my control station. So I'm also in the camp of preferring these are not added to RTR models, I just want a more basic version to add my own details the way I like.

[ColinB]

I think you are missing the point. Take for instance the Hornby Black 5, most railway modellers probably already have one and given the new price why would anyone want to buy one. As the Hornby marketing strategy is targeting mature modellers with spare income (they are probably the only ones left that can afford the new model). So what you do is add features to persuade the collector to bin their old model and buy the new one. Car manufacturers have been doing it for years. I can see the point in dumping a tender driven loco to a loco driven one, but after that the choice gets a bit hazy. Take for instance the new tooled Evening Star, will it be substantially better than the old loco driven one, but by announcing it as a retooled version people will buy it, even if they have the old one.

[VESPA]

I am not joining the mugs club of paying over £230 for a model with flickering firebox, choo choo sounds etc. The less that get's sold will become evident as these prices go uuuuuuuup. How many of the collectors think thaey are covered under their house insurance in the event of a disaster (fire, water damage)? I know we are going off topic for this thread but how come some items are over 50% reduced at certain retailers. Non sellers, shift them at trade or less. Far too expensive springs to mind.

[ColinB]

Actually if you want the flickering firebox Peters Spares does the part, I think it is about £4.00, so to Hornby less than 50p. It is useful on locos with DCC as it illuminates if there is DCC power on the tracks, so when you are trying to work out why the loco won't run, it is an easy indication of power on the tracks.

[threelink]

What's all this about "flickering" fireboxes? Prototype fireboxes did not flicker. When the loco was in the collar the firebox emitted a constant white hot light but only when the firebox door was open. At rest the light was more yellow/orange even with the blower on but still constant, not flickering. Why pay extra for something that is unrealistic?

[DarkRedCape]

Does the flickering firebox come on the R3711 and R3713 models?

Edit: happen to have a Hornby 2020 catalog and the R3711 and R3713 are both listed, and both stated as having the flickering firebox feature.

[ColinB]

Yes DarkRedCape I am pretty sure it does. As I said in my previous post it is connected between the two power inputs on the loco not dcc controlled as the DCC decoder is in the tender. It is basically a couple of normal diodes to get dc and then a flickering led. Yes threelink it probably won't flicker in real life and would be nowhere near as bright. Hornby probably added it as other manufacturers do, the only difference in those locos because they want it controllable by dcc, they move the dcc decoder back to the loco. It is a Hornby bodge, but having said that, I quite like having it on the locos, I even retro fitted it so of my earlier locos. If you want to do it properly on a Hornby loco fit a function decoder to the loco to just control it.

[Topcat2018]

The firebox door(s) will be closed except when the fireman is shovelling in coal, so what's the point of a glowing firebox, flickering or otherwise? To have it glowing all the time is unrealistic, and if you have DCC do you really want to be switching it on and off all the time? If it was a circuit that automatically and randomly switched the glow on and off that would be more realistic.

How elaborate can we get? A circuit that switches on the glow more frequently when the train is going quickly, pulling a heavy load, going uphill?

Hmm! Maybe not a bad idea! I might design a circuit.

[DarkRedCape]

Whoa, seems to be a bit of a hornets nest of a thread!

I only asked because I’ve picked up the R3711 and R3713 and couldn’t find much info about them. They have a slightly different R number than the other locos in this range and they are generally £20/£30 cheaper than the others in this range, so I thought maybe they were without this feature.

[96RAF]

It would seem that the default for these special locos is firebox glow on only whilst the track is powered up (DC) or always on (DCC).

What you need is a decoder that allows random playing of coal shovelling which also cranks up the firebox glow function.i.e. If the firebox door is open to shovel coal in you can see the glow.

Your new Hornby sound decoders will allow ‘programming’ of certain auto-functions for when the loco is stationary and certain auto-functions for when moving.

[ColinB]

Yes 96RAF that sounds great, but unless Hornby move the DCC decoder to the loco rather than the tender, it is not going to have much effect on the current firebox glow.

[Topcat2018]

I'm designing a circuit that will cause the firebox to glow at intervals that will depend on the voltage applied to the loco, so that firebox glow will appear more frequently when the loco is going faster or pulling more strongly. This will only work on DC as the voltage on DCC doesn't change.

What I'm trying to work out is how long the fire box door(s) should be "open" and at what intervals, to make it look realistic.

[atom3624]

That sounds great TC.

There have been some fantastic 'preserved steam heritage' videos on YT lately with later returns during the darker hours, and the firebox flare flickering into the exhaust smoke.

Al.

[Topcat2018]

@Al

What I had in mind with regard to intervals is that in real life, depending on how the loco was working, shovelling coal into the firebox might only occur at infrequent intervals, in which time a model loco might have gone round a layout. Can we compress the time frame on the model without it looking unrealistic, and by how much?

[Topcat2018]

Firebox Glow Concept

FIREBOX GLOW CIRCUIT FOR DC (ANALOGUE OPERATION)

This circuit provides a firebox glow for locos operating on DC that simulates the firebox door(s) being opened and coal shovelled into it at intervals depending on the operating condition of the loco.

When only a small voltage is being applied to the loco the glow will appear for short times at longer intervals and will be dimmer. When a higher voltage is being applied to the loco, such as when the loco is travelling faster or under heavier load, the glow will appear more frequently and for longer intervals, and will be brighter.

Note that this circuit will only work where both left and right loco wheels are connected to the track, which means locos with the motor in the loco, and (Chinese-made) tender driven locos where both left and right loco wheels have pickup contacts. It will not work with British-made tender-driven locos where there is only one connection from the track via left-hand wheels to loco chassis and the other connection to track is in the tender.

The circuit operates as follows: it is basically a voltage controlled oscillator whose frequency will increase and duty-cycle decrease as the as the supply voltage rises.

Diodes D1 to D4 rectify the track voltage so the same polarity is applied to C1 whichever direction the loco is travelling. R1 simply limits the inrush current to C1 to protect the rectifier diodes.

Operational amplifier A1 and A2 operate as comparators. Nothing will happen below about 4 V because the op-amps don't function below 3V and because of the forward voltage drops of the rectifier diodes.

Diodes D5 to D8 provide a reference voltage chain. C2 will initially be uncharged, so the output of A1 will be low because the voltage at its non-inverting input will be lower than that at its inverting input (maintained by D5-D8). Because the non-inverting input of A2 is only about 0.6 V (from the cathode of D7) its output will go high, so LED1 will be turned off. R6 provides a small degree of positive feedback (hysteresis) so the low-high transition of A2 will be quick.

C2 will now charge via R2 until the voltage on the non-inverting input exceeds the input. The speed at which this happens will depend upon the supply voltage. This is the interval when the firebox door is closed .

The inverting input of A2 will now be at a higher voltage than its non-inverting input, so its output will go low and the LED will light. The brightness of the LED will depend upon the supply voltage.

C2 will now discharge via R4 and D9, the discharge time being faster than the charge time because R4 has a lower value than R2. This determines the ON period of the LED.

The timing components R2, R4 and C2 will need to be determined by trial and error to see what values give the best visual result. I am going to breadboard the circuit and try it on one of my P2's then design a small surface mount PCB to fit inside the firebox if it works.