I know that if you do certain bad things to a dcc decoder it will all of a sudden let all the smoke escape and you have to go get another one…[;)]
But, when I had the shell off my Atlas GP-7 yesterday, probing around to see what I could mess up. I saw that the front light has a long-ish clear plastic rod extending from the front lens to close to the bulb. From the way it’s designed it would be a little hard for the manufacturer to tape or place the bulb in exact position for getting light out of the front lens, so is this rod a kind of collection device for the light, or how does that work?
I know I didn’t explain this very well but maybe someone will understand.
The general idea, as stated, is the density of the plastic causes internal refraction which causes the plastic piece to act like a tunnel for the light. I see it a lot in reverse lights for tenders on steam. (Because the bulb is in the base floor board) Luckily these don’t have to be that bright.
Yeah, it’s a poor man’s light pipe. It takes a nice light source and reduces it to a twinkling of starlight by the time it gets to the headlight ports.
"Just like an orange that turns up juiceless,
These silly things are just plain useless."
I have a P2K S1 that had a bulb at the hood end, but they used one of those silly things for the cab-end headlight. I tried to live with it, but I like to run at night with the lights low now and then, and it just didn’t cut it. I ended up taking the whole thing apart and mounting a LED in the cab.
Thanks for the answers. I didn’t think that a piece of plastic could conduct the light very efficiently, maybe better if the inside of the cab was painted white it would work better i.e. not lose all the light by it being absorbed by the dark insides of the shell.
JaRRel, the colour of the surrounding medium is inconsequential to the refraction process behind the tubular surface of the plastic rod. The whole point of the physics is that the light gets internally bent to such an extent that about 70-80% of it gets shoved out the blunt front. In better grades of plastic, i.e., with better optical qualities and densities, the refractive index of the rod is even better. So, surrounded by white, silver, or jet black, it is the plastic rod’s own properties that make it do what it does.
I think all locos of any quality should have LEDs these days. Grain bulbs are ancient, if cheap, and are unreliable.
I’ve found that getting some “Bare Metal Foil” in the model car section of the LHS and applying that to the outside of the clear piece works well. The foil has an adhesive on it to hold it in place. One sheet of the stuff can do a whole fleet of loco’s. Get the “Ultra Bright Chrome” color for best results.
In Atlas Kato engines it is a light pipe that channels light from a Single 12v bulb to the front/back headlight and number boards locations. One bulb could illuminare 3 - 6 locations on the cheap.
JSR made 'drop in C.V. light board boards that allowed more realistic constant, directional lighting that worked in Kato built chassis, which at a time inclded Atlas, and Stewart. One replaced the plastic rod with individual 1.5V. G.O.R. 30 ma bulbs.
Was this an improvement? sure, at a cost of $1 per bulb and $10 - $15 per engine. So you see you can have better lighting at a cost: - more money, time spent for work, and the first 3 volts going to the light board. Power is applied to the engine, the lights come on, and then the engine starts to move.
Later Atlas engines had 14v bulbs, fore & aft, that didn’t become bright until full speed had been obtained. Is that better?
LEDs without the CV circuit aren’t much better. Can they burn out? YES, and they DO - in spite of what you may hear.
I just had the shell of a Kato SD38-2 off so I could apply some detailing parts. There were two bulbs of the electronics board and two “plastic pipes” to direct the light to the front and rear headlights and number boards. Seems to work quite well. One thing I didn’t understand though, I had to drill out the shell for the rear number boards so they would be illuminated. Wondered why they came this way.
I would recommend replacing the plastic tube with a LED and properly sized resistor. That ia what I did to a KATO SD-40-2 recently. I use a variable resistor to get the bulb’s brightness right then measure the Ohms on a multimeter to select the right resister. If I can’t get an exact match, I go with the next size bigger. It has worked so far without blowing an LED. I’ve converted about half of my fleet of 50 engines. Tweet.
I was going to say much the same. What this does is to keep light inside the tube / it bounces escaping light back in…
If the tube runs over the top of the cab you can leave some of it unwrapped so that the leaking light gives the cab a faint glow - as of the lights on the instrument panel.
Something that I’m interested in is keeping the lights on all the time with minimal power use and/or heat… easy with DCC I think but not so easy with DC… either way… it is the power use and possible heat that concern me… Ideas anyone please? TIA [:)]
Use a resistor to knock down the current flow to the battery. That will limit overall lighting circuit heat generation, but the power consumption will be nearly the same due to the resistor.
DC:
Much harder to do, but is possible using a very low voltage bulb(<1V) hooked up to a voltage regulator which in turn is hooked up to a Full wave Bridge rectifier. Then you need to find a way to keep the bulbs voltage on the track all the time w/o making the loco’s engine roll.
I thought that would be the answer… [%-)][%-)][%-)]. Guess I’ll have to wait until I get round to DCC… or find someone I can co-opt who knows what he/she is doing…