DCC firebox glow
Keep the Fires Burning
Geoff Byman
The warm glow of a flickering fire always gives a feeling of life to a room, and creates an extra dimension of realism on the footplate of a model locomotive.
Not all of my locos have firebox glow, as most have the fire door closed, but a chosen few do. As they chug slowly by working hard on a goods train or thunder along with a high speed express, a glimpse of the fire just adds that little something. It’s not just the sight of the fire through the fire door, but also the glow on the crew and around inside of the cab; it gets even better on the garden railway as the sun goes down.
Running with DCC, whether sound chipped or not, the firebox flicker can be added. If you’re not running DCC and run on DC only, the same can be done for very little expense, since the latest decoders can all run on either DCC or DC. When run on DC, the firebox automatically comes to life as the power is applied. With the low cost of a cheap chip, the TCS-T1 costs only around £17 or £18, this effect is not way out of pocket. The chip can have acceleration and deceleration, along with good slow speed control, programmed so that it will be as effective with DC as it will with DCC. If you are running DC, then you’ll obviously have to get the chip set up by someone (a friend, maybe) with DCC equipment.
The only other small expense to
complete the set up is for a couple of LEDs
(Light Emitting Diodes) and resistors,
which should only add around another
pound or two to the cost. It is possible to
get flickering LEDs, but they are not very
effective for firebox flicker and the
controlled effect that can be gained with a
DCC decoder is well worth the extra cost.
The roaring fire of a hard working loco has a nice feel to it. Note the glow of the fire on the crew and surrounds
Building the fire.
Creating the fire effect is a simple wiring
job, using two 3mm LEDs, one red and one
amber or yellow. Each LED needs a resistor in line to drop the voltage from 12volts to
that of the LED (usually 2 to 3volts) a
resistor of 1K ohm should do the job nicely
(see picture 2). These can be obtained
through various outlets on the internet or
from your local electronics store such as
Maplins, or possibly from your local model
shop, for around a pound or less. 12volt
LEDs are obtainable and would eliminate
the need for resistors if space in the
model’s firebox is limited.
Picture 2. LEDs, resistors and mounting board, with one set soldered together
I usually make up a base and backplate
from either 3mm MDF or 0.060in
Plastikard, or some other suitable
insulating material (see picture 2). In the
photo the LEDs have their terminal pins
bent at 90 degrees so that they can be used
to support the lamps in a vertical position.
Next, the resistors are soldered to the LEDs anode terminals. It is important that LEDs are connected the correct way round. Wiring diagrams may be labelled a or + for anode and k or - for cathode. The cathode is the shorter terminal/lead (note this before you cut them short) and there may be a slight flat on the body of round LEDs, but beware that this flat position may vary depending on manufacturer, so it’s best identified by the length of the terminal/lead. If you can see inside the LED, the cathode is the larger electrode. Although LEDs can be damaged by heat when soldering, the risk is very small (unless you are very slow with the soldering) avoiding the need for any form of heatsink.
The other terminals (the shorter cathode terminals) are soldered together using a length of off-cut from the shortened LED terminals as a bridge, and then soldered to the blue wire of the decoder (see picture 3).
Picture 3. Assemblies wired and glued to insulated mountings. Reflectors, one crinkled, made from aluminium foil, ready for fitting.
Next, the white and the yellow leads from the decoder are soldered one to each of the resistors (see picture 3). It doesn’t matter which colour lamp you solder to which colour wire because both wires (which are used normally for forward and reverse lights) are to be set in the decoder CVs (Configuration Variables) as nondirectional. The excess length of the terminals can now be trimmed so that they don’t protrude beyond the insulated base.
Finally the whole lighting assembly can be fixed to the insulated base with glue (see picture 3). I use a hot glue gun for this job. It attaches the assembly quickly and the glue acts as an insulator. To complete the job, a small piece of aluminium foil is crinkled and glued behind the LEDs to act as a diffused reflector to scatter the light.
Picture 4. Two completed assemblies ready for mounting in body or chassis, the crinkled foil now behind the LEDs to spread the light.
Do make sure that none of the foil touches any of the electrodes or wires (see picture 4). The completed unit can now be fitted in place behind the backhead, either in the body or mounted on the chassis. If you are mounting the assembly in the body you will need a miniature three pin plug and socket to connect to the decoder, which is usually mounted on the chassis (see picture 5).
Lighting the fire.
Set the CVs on the decoder pertaining to the forward and reverse lights for ‘nondirectional’ running. This setting allows the fire to stay on at all times in DCC mode whether stationary or in forward or reverse motion. Note that the fireglow will only work when a current is available, so in DC mode the fire will only come on when the current is applied to the track. Obviously in DCC mode the fire will remain on at all times.
Using the decoder’s CV settings the lights can be set to produce various effects, one of which will be ‘flickering,’ ‘random flickering’ or ‘flickering firebox’ (depending on the decoder manufacturer’s terminology) or in the case of the ESU Loksound V4.0, ‘intelligent firebox’. This setting is quite effective, as the fire gently flickers while stationary and livens up (in both brightness and intensity of flicker) as the logo works harder, settling down as the engine coasts to a standstill.
Unfortunately the many makes and models of decoders do vary quite considerably with the CV numbers linked to these tasks, so I can’t list settings for all makes, but I have listed below some settings on the decoders that I’ve used. The variables in the list are my personal preferences and I have included these simply as a starting point. You will have to refer to the decoder instruction manual for more information and for those not listed to determine which CVs and settings to use.
On some decoders the flickering is not a continuous dimming and brightening, leaving gaps where there is no light at all, which obviously is not what we want. If this is the case, the red LED should be set to be continuously lit, and if necessary slightly dimmed to your own taste. The amber or yellow LED can be set for firebox or random flickering. On other decoders, where the flickering is a continuous dimming and brightening, then both can be set as firebox flickering. When you have set the CVs and are happy with the result, there is one final job to carry out. Once the locomotive is reassembled, take a small piece of thin, cheap, kitchen towel (I find the thin multidimpled economy type ideal) just a little (gentle pushing and poking with a cocktail stick to get the position right will help). Note that you are not looking for a smooth covering, but a slightly crinkled arrangement will help create the effect of flames. Once you are happy with the positioning, a few small blobs of superglue will hold it in place. This final piece of diffuser acts to give a lovely flaming fire look and a warm glow in the cab. Happy firing
Picture 5. Assembly mounted on the chassis of an
A4 and ready to run.
Picture 6. The cheap paper towel light diffuser is pushed into the firehole.
Examples of CVs and settings
The tables show my preferences for variable settings i.e. brightness and flicker rates, and are quoted as examples to work from.
| Decoder make/model | Non-Directional | Flicker and Brightness | ||
|---|---|---|---|---|
| TCS-T1 (sets red LED to constant; CV49+50 also et non-directional) | CV49 = 44 | CV50 = 33 | CV135 = 15 | CV157 = 25 |
| Zimo MX64H | CVs 33 and 34 both = 3 | CVs 125 and 127 both = 8 | CVs 126 and 128 both = 0 | |
| ESU Loksound V3.5 | CVs 141 and 144 both= 3 | CV113 = 85to 89 | CV 114 = 9 to 12 | |
32 must be set first to allow access to the higher number CVs required to achieve the correct settings listed under. Unless these are set first, the settings for the higher CV numbers will be for other functions.
| ESU Loksound V4.0 | CV31 = 16 CV32 = 0 |
|---|---|
| Settings for flicker and brightness. CV259+267 random flicker = 3 or as set here (4) is intelligent firebox. | CV259 and 267 both = 4 |
| CV 262 = 30 | |
| CV 270 = 21 |
| Note: CV32 value changed to access correct settings on CVs330 & 346%% | CV31 = 16 CV32 = 2 |
| These settings set LEDs to nondirectional | CV330 and 346 both = 3 |
