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It Colombo time again. I would like to use black electrical tape to block the light from coming back into the passenger care from the mark lights on the observation cars. To hold this in place I was think of  using duct tape. Good idea, bad idea or off the wall or does someone have a better idea?  This is using the led from the reel not individual led. I know how to hook it up via the other thread. 

 
Originally Posted by RJR:

I've been using the reels of LEDs.  I am finding that the strips are coming off whatever they are on, like car ceilings and the underside of station roofs.  Anyone else have this proble?

I read that other users of the reel LED's had issues w/ that item's adhesive backing in other applications.  A number of people responded and suggested to use a high quality 3M brand double sided foam tape to secure the LED reel tape to where you want it to stick.

Originally Posted by Super Dave:

 

I use a low value PTC between the rollers, no fuses to replace if I have a derailment.  For MTH Premier cars, I hide them in the wiring in the base between the two pickups.

 

GRJ, what exactly is a low value PTC and is it wise to use on all the cars I'm converting?  Part number too please. Thanks. 

Its a thermally effected resistor of sorts. In this case, too much current, and it gets it hot, and it slows, or cuts off current flow. Like a resettable fuse, once the over current draw is removed, it will drop in temp, and current will flow again.  

 Something like a ballast resistor on automotive point style ignition system.

 

I am trying a simpler approach. I am planning to use 12VDC bayonet base led arrays (bulb). I purchase 20 of them for a buck a piece on eBay. Each unit has 5 LED's over a std #53 bayonet bulb base. In the basic operation all that's needed is rectification and filtering but this will require isolating the bulb socket from the frame (or using a two lead bulb base). I am using LED's for automotive applications so they should be safe in the 12V-14V range. I seldom run trains at higher voltages than that but if we go higher than a regulator gets spliced in. If the lighting proves to be too bright I have a bottle of yellow bulb die where a couple of dabs gives the light a slightly yellow soft look.

Originally Posted by Dennis LaGrua:

I am trying a simpler approach. I am planning to use 12VDC bayonet base led arrays (bulb). I purchase 20 of them for a buck a piece on eBay. Each unit has 5 LED's over a std #53 bayonet bulb base. In the basic operation all that's needed is rectification and filtering but this will require isolating the bulb socket from the frame (or using a two lead bulb base). I am using LED's for automotive applications so they should be safe in the 12V-14V range. I seldom run trains at higher voltages than that but if we go higher than a regulator gets spliced in. If the lighting proves to be too bright I have a bottle of yellow bulb die where a couple of dabs gives the light a slightly yellow soft look.

Dennis:  do you have an item number for these bulbs on eBay?  Bob S.

Originally Posted by nvocc5:

Dear John

 

MTH 30-2162-1 the unpowered units I got the change over down pat.  However, the powered unit scares me. I already installed the PTC in all the unit I have converted. I am scares one wrong connection I have magic smoke and fried board. Any suggests?

For powered units, specifically that set, I'd probably use my 1.3A trip PTC.  Since that will only ever be pulling four cars, and the load is shared a vast majority of the time, that should be sufficient.  Other than that, wiring the lights is the same.  You shouldn't be doing anything around the board, we're just using track power here.

 

Originally Posted by RJR:

GRJ, Digikey is great if someone gives you a link to a page, but I find a raw search yields a daunting list.

True, but if you spend a little time on Digikey, you can learn how to narrow the search.  When I started buying there, I had the same impression, but now I'm pretty good at zeroing in on what I'm looking for.

 

 

Originally Posted by DaveJfr0:

Do PTC's have a lifespan?  (100, 1000, 10000 uses) before they're done?

 

I think I will start throwing these into my DCC conversions too…

PTC units do have a finite lifetime, but that's for number of trips.  Since the object of the exercise is for them not to trip, they should last a long time.

 

You can spend more money and get some really high trip counts, the ones I use are specified in the 100's of trip cycles.  More expensive ones ($10 and up), can have 20,000-30,000 trip cycle specifications.

 

Here's a chart for PTC's similar to the Littlefuse ones I use, this was taken from this Polyfuse (resettable PTC) lifetime page, some useful information on PTC reliability and MTBF.

 

Originally Posted by RJR:

What resets them?  If they reset automatically after a period of time, they could do a lot of trips.

Ralph, for everything you wanted to know about thermistors but were afraid to ask check out Wikipedia. You can gloss over the equations if you choose. The descriptions of the various types including this specific type of Positive Temperature Coefficient thermistor should be pretty clear.

 

http://en.m.wikipedia.org/wiki/Thermistor

 

Pete

Even if you leave them tripped for an extended length of time, that's not a major issue, they test them up to 48 hours.  If you're walking away for hours and leaving a derailed train on the tracks, one would presume that you're pretty much going to have problems with many things, and not just the PTC that's protecting the wiring.  Without the PTC, you will likely have more damage, either a cooked wire or some welding on the tracks, wheels, and pickup rollers.

 

I'm not seeing this as a problem, but if it is for you, I suggest not using the PTC.

 

I'm going to go out on a limb, hoping GRJ isn't "painting" yet.

This simple of a drawing, He's probably hoping someone else will draw it anyhow

I'm also going to leave the LEDs alone for a bit, as he likely has something like this done already.

 

I've never done this roller mod myself.

But, I think the ptc should be as close to the roller as you can get it, basically on it. 

One ptc, would protect roller to roller issues.

Two ptc-s, I'm still thinking of the right disaster scenarios for it, but I like the overkill just seeing it there. 

   

ptcrollers

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  • ptcrollers

Since the current is the same everywhere between the rollers in the derailment scenario, the PTC can be anywhere in the wire between the rollers with equal effect.  Since it gets pretty warm when it trips, the best idea is to put it where that won't damage anything in the event it is actuated.  There's no benefit to having multiple PTC components in the roller wiring.

 

Originally Posted by RailRide:

Here is my "clump", designed with the help of our electronics gurus:

 

package with annotoations

 

And here is a MTH Superliner sightseer lounge with the LED's powered off the above circuit. Both levels are lit, three segments on the lower and eight on the upper. I tapped the power rails for the lower level light bar to supply current to the circuit. That way I could reuse the stock light bars, and the LED's shine through yet remain recessed into the ceiling. 

34-sightseer lounge4

 

---PCJ

So off  of the LM317t the furthest pin is "input" and the closest pin is "output" with the 300ohm resistor, and the center pin is left alone? Just making sure before i create my clump and blow something up! Although that would be fun

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