I think I have read that I can use a light bulb to protect my electronics from shorts...any idea how to do this?
Yes and no.
I use a 1156 car light bulb to limit the current for my NCE Powercab to under 1.5 amps. It works well for me.
The theory is that a cold filament in a light globe has a low resistance, so long as the current thru the globe stays at that low level there is very little voltage drop in the globe, but once the current reaches the point that warms the filament sufficiently, the resistance increases and prevents the current form getting so high it causes damage elsewhere in the circuit.
If you have a large layout it is best to use several globes, each one feeding a seperate part of the layout.
Two big advantages are you get visual indication of a short and it resets automatically once the short is removed.
cheers
Alan Jones in Sunny Queensland (Oz)
An automobile taillight bulb like the 1156 in series with the device you want to protect will work as long as the bulb does not drop the voltage to the point that the device will not function.
LION has been looking at this. It worked just fine with one or two trains running, but LION runs 6 to 12 powered units on his railroad, and that of course is enough to light the light. Since LION uses a regulated supply with a 15 amp capacity he still got the full 10.5 volts,on his tracks, but the light is meaningless.
LION will need to buy about 10 lamps to properly cover his layout for this kind of protection.
ROAR
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
As Alan pointed out, use of a light bulb instead of a circuit breaker limits the current, but it doesn't shut it down completely. That could still be the difference between a full recovery and a short that causes permanent damage. Also, having a current-limiting device in the circuit will prevent any built-in circuit breaker from tripping.
I have a lot invested in my layout. If something goes wrong, I want all the power to that district to be shut down.
It takes an iron man to play with a toy iron horse.
The above answers are true if you are running HO or N scale. If you are running a larger scale, a larger bulb is required. You want the bulb not to light when trains are running and everything is OK. When there is a short, the bulb should light brightly.
Although this is a poor mans circuit breaker of sorts, I would recommend that you do not rely on it to protect electronic circuits and equipment. The light bulb is a work-around for people that are cheapskates.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
The simple answer is, NO, a light bulb is not a substitute for a circuit breaker unless the current flowing through it is so high that the filament burns out. The only thing the bulb will do is limit the current flowing through the short circuit.
One of the most important fundamentals of electrical circuits is short circuit protection, These bulbs defeat that. Buy a solid state breaker. The 1156s belong in the back of classic cars, not as a substitute for a circuit breaker.
Jim
Lights like this are NOT cheaper than fuses or circuit breakers. They cost money, and even more if you want the fancy holder that they might come in. LION has stacks of 3 Amp fuses all over the place. You know, all of those strings of LED Christmas lights that I have been cutting up come with four fuses in them. At the moment they are still rolling across my desk, and I will have to capture them and put them in cages before they fall on the floor and become shards of glass.
What the Light buys for me, and what the fuses cannot, is letting me know where on the layout the problem exists.
LION has emergency power cutoff buttons all around the layout (prototypically marked with blue lamps as per NYCT protocol) from where I can cut all power off no matter where I might be around the layout.
Light comes on, LION pushed button, goes fixes problem.
No Problem.
again let me say thanks to everyone's input. I don't mind using the circuit breakers but I had read something that sounded logical. I am building an O layout 8' x 12' with 3 loops to run 3 trains seperately. I will be using TMCC. I appreciate the suggestion of having emergency cutoffs at several point that can easily shut off all power.
BroadwayLion Light comes on, LION pushed button, goes fixes problem. No Problem. ROAR
How about using some LEDs as track power indicators?
Light goes out, Lion pushed button, goes fixes problem.
No Problem
Meow
That 1156 taillight bulb will limit you to 2.2 amps as it heats up and glows. As others have said, it is a passable DCC current limiter, but it does not really protect your expensive TMCC stuff. I used four 1156 bulbs to create power districts on my Digitrax DCC layout. If they were glowing, you knew there was a problem, but the stopped train also told you that! I now have a Digitrax DCC PM42 that provide power district protection to four power districts - The power is shut off immediately in the power district if there is a problem. I do not know if DCC stuff will work on your TMCC layout. Maybe you will be better served asking this on the 'Classic Toy Trains' forum. The MR forums are usually for 'scale' model trains(HO & N for the most part).
Modeling BNSF and Milwaukee Road in SW Wisconsin
"O" gauge TMCC requires 18 volts 60 cycle on the rail to operate. A simple cut off switch on each loop is enough to isolate loops. If using only one transformer the breaker in the transformer will "kill" the whole layout. Just to note, TMCC is a radio control using the outside rail as the return. The center rail is not part of the control system.
On Line of LION there are 14 scale miles of track, lots of it in tunnels with eight trains running at once. Trains stop at stations all of the time. Me thunked of track LEDS but thems too small to see.
Power Supply will seldom trip, is big 15 amps, it only takes 3 amps to burn up a trackside resistor, the power supply will never see it. But a lamp will take the current and light itself up protecting the stuff, but of course those trackside resistors are not rated for that lamp either.
When you build unique system you find new and unique problems. Best answer is these 3 amp fuses all around the layout, at every major power point.
Still planning, still changing
BroadwayLionBest answer is these 3 amp fuses all around the layout, at every major power point.
Have you considered a resettable 3 amp breaker?
Thanks. I guess this is put in the hot line, or my middle rail on 3 rail o guage?