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LED passenger car interior lighting

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LED passenger car interior lighting
Posted by jddav1 on Friday, February 8, 2008 9:18 PM
I'm looking for a small circuit board for lighting passenger interiors on Walthers lightweight as well as heavyweight cars with LED's.  I do not want to use those expensive commercial units in catalogs.  My power is DC and would like bi-directioal operation.  If they are small enough, I will use them to light caboose with marker lights also.  Thanks for your help.   JeffSmile [:)]
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Posted by PHARMD98233 on Saturday, February 9, 2008 9:34 PM

Browse around this site for those items.  I have started using the LED strips/tapes for lighting passenger cars.  It is a nice product which comes in 2 inch increments containing 3 SMLED's.

Also, there are numerous sites on the web with good instructions for growing you own.

http://www.trainaidsa.com/

 

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Posted by MisterBeasley on Saturday, February 9, 2008 10:34 PM

As you probably know, LEDs must be driven with the correct polarity, so running on DC is a problem.  In one direction, they'll light, but in the other, they won't.  Yeah, you could come up with a circuit to provide the right polarity, but why bother?

LEDs are cheap.  For a typical passenger car, 2 or 3 should suffice.  So, buy 4 or 6, and wire one set to run when the car goes forward, and the other when it goes in reverse.  It's cheaper than the circuitry to keep the same LEDs on all the time.

It takes an iron man to play with a toy iron horse. 

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Posted by Mark R. on Sunday, February 10, 2008 12:44 PM

Correct me if I'm wrong ....

Why couldn't you just use a single bridge rectifier and connect the DC track power to the AC connections on the bridge - the output on the + and - leads will always stay the same regardless of the polarity on the rails. The diodes within the bridge will create a slight voltage drop, but that can be corrected with a lower rated resistor.

Mark. 

 

 

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Posted by BigRusty on Sunday, February 10, 2008 4:08 PM

Mark, I agree the bridge rectifier is a good solution to DC operation of LEDs on 12 volts. I am concerned with what happens to the light output when the voltage is lower due to slower operation of the engine

With the high rate of interest that is being generated on detailing passenger car interiors, I would really appreciate it if you electonic whizzes would develop a circuit that we can make ourselves using the mini surface mount LEDs on a self made light strip. It could be from etched perf board or just a narrow strip of 0.10 styrene (like the HD sign material). Bare 14 gauge wires could be threaded through holes at either end and stretched taut on either side with the LEDs soldered between them at suitable intervals.

For my purposes, I would like a circuit that includes the bridge rectifier, and a capacitor to prevent flickering, and maybe keep the lights on for a minute or so.

Modeling the New Haven Railroad in the transition era
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Posted by Mark R. on Sunday, February 10, 2008 4:46 PM

With the proper value of resistor on the LEDs for the full available 12vdc, there will still be a slight variation in brightness, but nothing like that compared to a filament bulb. Granted, anything below 1-1/2 to 2 volts, the LEDs will still go out.

I built a caboose using two LEDs for interior illumination and installed one of the computer back-up capacitors in the line with an external resistor to slow the drain. I can remove the caboose from the track and the two LEDs will stay illuminated for a full two minutes before they begin to dim and go out. The capacitor is only about 1/2 inch in diameter and 1/4 inch thick so it can be easily hidden. The circuit I used was from a constant lighting article using these capacitors that was from an MR article a number of years ago (sorry, I don't recall the issue at the moment).

Mark.

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Posted by spikejones52002 on Sunday, February 10, 2008 5:00 PM

With LEDs drawing so little power.

Why not use AA battery power for each car. You can easly hide two AA under the car, Using recharge also.

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Posted by BigRusty on Monday, February 11, 2008 5:40 PM

Batteries cost money, need to be recharged or replaced. Track Voltage is free. It would require a small switch on every car to shut down the lights when not in use. Not an option with almost 50 passenger cars.

I would consider a circuit that utilized a battery that could be chargd by the track voltage and would keep the lights on when stopped in a station.  It would also require a small slide switch to shut down the lights when not in use.

Modeling the New Haven Railroad in the transition era
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Posted by spikejones52002 on Tuesday, February 12, 2008 7:15 AM

Nothing is FREE except options. You use the one that fits your needs.

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Posted by Phoebe Vet on Wednesday, February 13, 2008 6:26 AM

 jddav1 wrote:
I'm looking for a small circuit board for lighting passenger interiors on Walthers lightweight as well as heavyweight cars with LED's.  I do not want to use those expensive commercial units in catalogs.  My power is DC and would like bi-directioal operation.  If they are small enough, I will use them to light caboose with marker lights also.  Thanks for your help.   JeffSmile [:)]

I agree with MisterBeasley.  All the other solutions are needlessly complex.

A bridge rectifier requires 4 diodes and the space for them. Add the LED and that's 5 diodes.

Beasley's solution requires 2 diodes.

Constant lighting is another argument for DCC.

Dave

Lackawanna Route of the Phoebe Snow

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Posted by Mark R. on Wednesday, February 13, 2008 2:56 PM
 Phoebe Vet wrote:

 jddav1 wrote:
I'm looking for a small circuit board for lighting passenger interiors on Walthers lightweight as well as heavyweight cars with LED's.  I do not want to use those expensive commercial units in catalogs.  My power is DC and would like bi-directioal operation.  If they are small enough, I will use them to light caboose with marker lights also.  Thanks for your help.   JeffSmile [:)]

I agree with MisterBeasley.  All the other solutions are needlessly complex.

A bridge rectifier requires 4 diodes and the space for them. Add the LED and that's 5 diodes.

Beasley's solution requires 2 diodes.

Constant lighting is another argument for DCC.

You better re-read MisterBeasley's response .... granted it DOES use only two diodes, but twice as many LEDs, PLUS the wiring to install twice as many !!! A single 1 amp bridge rectifier isn't much bigger than two 1 amp diodes side-by-side.

Two wires in - two wires out of a single component .... I honestly don't see how it could possibly become any more simplified !!!

Mark.

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Posted by Phoebe Vet on Wednesday, February 13, 2008 3:47 PM

Mark:

I'm not sure exactly what your argument is.

In Misterbeasly's plan, you hook two LEDs together in parallel, anode to cathode.  No rectifier or other diodes are required.  one will light when the right rail is positive or the other will light when the left rail is positive.  He did suggest two sets per car, but that would be required even with the bridge.  That's 4 diodes per car instead of 6.  Times however many cars you are lighting.

In actuality, you could use the 4 LEDs to build a bridge, but I don't know why you would want to.

I've always been a fan of the KISS principle.  The simpler the better.  Fewer things to fail.

I am not saying your way is wrong.  I  just personally prefer the simpler way.

Dave

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Posted by Mark R. on Wednesday, February 13, 2008 3:56 PM

Not really an argument per se, but just a reaffirmation of its simplicity. With Mr.B's approach, instead of four LEDs per car you would be using eight only for the sake of saving the use of two diodes.

Everyone has different approaches to what is simplest .... mine ? - I use DCC !!! Wink [;)]

Mark.

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Posted by Phoebe Vet on Wednesday, February 13, 2008 4:08 PM
 Mark R. wrote:

Not really an argument per se, but just a reaffirmation of its simplicity. With Mr.B's approach, instead of four LEDs per car you would be using eight only for the sake of saving the use of two diodes.

Everyone has different approaches to what is simplest .... mine ? - I use DCC !!! Wink [;)]

Mark.

I use DCC, too.

I guess I don't understand how you are counting.  He suggested 2 or 3.  That would be 4 or 6.  With half the number of LEDs but adding the 4 diodes in the bridge  that would be 6 or 7.  Obviously, the more lights per car, the better the bridge looks.  Break even seems to be 4 sets of lights.  The wiring is still simpler with pairs of LEDS.  But we are not talking great complexity either way.  You would need the bridge if you want to use your capacitor.

I'll stick with my DCC.

Dave

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Posted by Mark R. on Wednesday, February 13, 2008 4:24 PM

You seem to be fixated on the NUMBER of diodes being used .... are you basing that on load or cost ??? Either way, the difference is virtually negligable.

It's this kind of stuff that I really don't miss messing with having gone to DCC - never again !!!

Mark.

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Posted by Anonymous on Thursday, February 14, 2008 4:57 PM

The LED has a maximum reverse voltage rating, usually about 5 volts. It's not going to be necessarily evenly divided with LEDs that are in series so I wouldn't do this. The following posts with the bridge rectifier are a good idea.

 Randy

edit - I was referring to the MisterBeasley post

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Posted by Anonymous on Thursday, February 14, 2008 5:01 PM

Ooh 14 gauge? By the time it was heated enough to solder the LEDs the heat would melt something or clobber the LEDs. Do you mean 24 gauge which is just larger than telephone hookup wire?

 Randy

 edit - referring to BigRusty'spost on 2/10

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Posted by Phoebe Vet on Thursday, February 14, 2008 5:28 PM
 rbuckner wrote:

The LED has a maximum reverse voltage rating, usually about 5 volts. It's not going to be necessarily evenly divided with LEDs that are in series so I wouldn't do this. The following posts with the bridge rectifier are a good idea.

 Randy

edit - I was referring to the MisterBeasley post

A bridge recifier is diodes in series.  Misterbeasly's suggestion was to put LEDs in parallel.

While I am not suggesting the biger wire, all you have to do to protect an LED during soldering is to clamp a heatsink on the lead between the solder joint and the LED.

Dave

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Posted by Rotorranch on Thursday, February 14, 2008 11:12 PM
 rbuckner wrote:

Ooh 14 gauge? By the time it was heated enough to solder the LEDs the heat would melt something or clobber the LEDs. Do you mean 24 gauge which is just larger than telephone hookup wire?

 Randy

 edit - referring to BigRusty'spost on 2/10

I think he's referring to using the 14ga as a buss in the car, and attaching the lights (LEDs) to it.

 That sounds like a good idea to me.

With proper pre-tinning of the 14ga buss, the LED could be easily soldered WITH A PROPER SOLDERING IRON to the legs of the LED with a hemostat (or other heat sink) holding the LED leads to the buss, without transferring excessive heat to the LED.

The key to all soldering is having the proper soldering iron for the job.

Rotor

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Posted by BigRusty on Friday, February 15, 2008 2:39 PM

I think he's referring to using the 14ga as a buss in the car, and attaching the lights (LEDs) to it.

 That sounds like a good idea to me.

Yes, for rigidity. Even 24  ga would probably work current wise, but might have to be attached at intervals. Usinge a circuit card would be preferable. A simple circuit can be etched on circuit board mechanically rather than acid etched usining Dremel tool with a small round burr tip.

Enough of the pros and cons.

Can anyone post a circuit for a passenger car lighting system for DC operation that utilizes 6 or 7 mini flat diodes, a bridge rectifier and a capacitor to eliminate flickering. It would operate from 12V track voltage.

It can be mounted on an etch circuit board, and a bread board test can be made by stretching two parallel wires between which the diodes are soldered on a piece of styrene.

As an alternate to the capacitor I would be interested in using a battery that is recharged from track voltage. It may not be free, but it doesn't cost anything extra to use it.

I will gladly construct the bread board version, install it in a passenger car and post the results.

Modeling the New Haven Railroad in the transition era
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Posted by BigRusty on Thursday, February 21, 2008 2:19 PM

Is this HARD?

Input: +/- 12-14 Volt DC track voltage

5 to 7 flat LEDS ( voltage and Amps?) wired in parllel to bus wires

Capacitor ? Ohms

Bridge Rectifier ? Value

Even I can diagram that with the values furnished.

Example: What capacitor and bridge rectifier needed to drive 5  or 7 1.5 LEDS

Modeling the New Haven Railroad in the transition era
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Posted by Phoebe Vet on Thursday, February 21, 2008 2:26 PM

Capacitors are measured in farads (microfarads, picofarads, etc)

Resistors are measured in ohms.

Dave

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Posted by Mark R. on Thursday, February 21, 2008 3:24 PM

This is what I use in my cabooses ....

Track power in to a 1amp bridge rectifier connected to the AC leads. Capacitor connected across the + and - leads (be sure to observe polarity). The + and - leads are connected to the parallel buss for the LEDs. A resistor must be installed between where the capacitor is connected and the buss.

The resistor performs dual duty. First is to lower the current to the required level for the LEDs, and second, to slow the inrush of current from the capacitor.

For the capacitor rating, use no lower than 16volts. For the farad value, use as big as space will allow - the larger the farad value, the longer the lights will stay illuminated. Check out the capacitors used for computer power back-ups .... they are considerably smaller in size than regular capacitors of the same value.

The resistor is going to be a trial and error based on the number of LEDs in the circuit and how fast the capacitor will discharge. Temporarily install a 1000ohm pot where the resistor will go and set it to maximum resistance. With the circuit setting on the rails at full voltage, adjust it down until the LEDs are at full brightness. Remove the pot and using your meter, read the ohms at that setting and install a similar value resistor in the circuit.

That's how I do / did it, and it works great. The lights will stay on for a considerable length of time even after the caboose is removed from the rails .... even used it as a quickie light one night the hydro went out  - enough to get me out of the train room !!!  LOL

Mark. 

 

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Posted by brucedouglassza on Friday, February 22, 2008 1:15 AM

Jeff , your problem here is DC . as said before , depending on the voltage input.

1  my suggestion is to use rechargable batteries(leds require 2-3volts to start & run on about 1.5volts) & connect a few cars together with plugs , leds wired in parrallel, charging from the track as needed.

 2  use a volatge regulator  , the smallest  you can get  ,  in South Africa I have found 3 volt .

3  or a LM317 with pot. 

all the above circuits require a rectifier & do not forget the heat sink !!! 

Nos 2&3 will require a minimum voltage of about 5volts , & a Capacitor to stop flicker.

 remember the more leds connected in parallel the more juice is required . 

These ideas came from one of the books by Peter Thornton. 

 one of DCC advantages , constant voltage.

Regards

 

Bruce 

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Posted by genelewis on Sunday, February 24, 2008 10:10 AM

The circuit that BigRusty describe"s is available on the web.  Click this link to review.

http://www.thegmlenterprises.com/id13.html

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