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upguy posted:

...

If I convert the car to LED lighting, what size and shape LED might fit in the space now occupied by the bulbs.  Would I then be able to attach them to one of GRJ's lighting strip boards along with the white LED lighting strip?

I think you'll find a suitable LED no problem - as to the 2nd half of your question, the most common method of adding a pair of red marker LEDs to a lighting strip requires an external resistor.

2 red leds plus a resistor

So as illustrated above, you'd run a pair of wires off the end of the powered LED strip (driven by GRJ's module) and insert an external resistor in series with the 2 red LEDs.  If this is the wiring approach you're considering, one of us can find the relevant OGR threads or do an Advanced Search using the relevant terms.  It's just that there are variations on adding external LEDs to a lighting strip which affect the desired resistor value...something around 1K Ohms.

It's just that if you're ordering LEDs from DigiKey, minds as well order a handful of 5-cent resistors too since shipping is $4-5.

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  • 2 red leds plus a resistor
Last edited by stan2004

Thanks guys for the good information you are posting here may try this in some of the 3 rail passenger trains.

I happened to see and pickup at a store, 6 feet of LED peel and stick white LED lights roll with a battery pack taking 4 AA batteries for $15. Can be cut and spliced. Runs for 60 hours on a new set of batteries. Going to try this in a set of my O scale 2 rail passenger cars and remove the power pickup wipers from the wheels that are giving me a lot of drag, hopefully will allow me to pull it with my O scale steamer that now slips with the cars with wipers. Battery pack should fit in tender will add a switch within easy reach. 

GRJ,  After upgrading my Kline, MTH and Lionel passenger cars with the OSH boards, I adapted one of the boards to run the tunnel lights in our mountain tunnel, it really helped having the ability to reduce the current with the trimmer pot, so these are very universal in running LED anywhere.

Last edited by Ron_S
Ron_S posted:

Stan, am I reading it right, that you use a 1k resistor from the led strip to the red led marker lights in series?

Ron, I "tune" that resistor, depending on how bright I want the lights.  1K is usually a decent starting point for the side markers on the passenger car with two red LED's.

Ron_S posted:

GRJ,  After upgrading my Kline, MTH and Lionel passenger cars with the OSH boards, I adapted one of the boards to run the tunnel lights in our mountain tunnel, it really helped having the ability to reduce the current with the trimmer pot, so these are very universal in running LED anywhere.

Yep, I had to have a way to adjust the intensity of the LEDs for upgrades, I learned that after doing a number of cars.  That was high on the list when I did the lighting modules.

As GRJ says, you'll probably need to "tune" the value of the resistor.  1K is simply a starting point to get you in the ballpark.  Note that adding the red marker LEDs plus resistor off the end of the LED strip will siphon current from the white strip LEDs.  So if you already had a desired brightness on the interior lights, you'll need adjust upwards the control on GRJ's board.

Most guys probably don't have a stash of resistors lying around to "tune" the marker brightness.  That is, you might just have purchased a pack of 10 or 100 1K resistors.  Note that for experimenting, you can simply put 2 1K resistors in series to get 2K (which will about half the marker brightness), or put 2 1K resistors in parallel to get 500 (which will about double the marker brightness).

Or, if you see more DIY in your future, why not get a resistor assortment for less than a penny per resistor (free shipping from Asia) which includes 1K and other values - one of which will surely be suitable for the matter at hand.

resistor assortment less than a penny each

But back to the red LEDs.  

red leds for marker lights 

Another reason you'll need to tune the resistor is there is a substantial difference in brightness (for a given current) between red LEDs.  I've found the ceramic stem type (bottom of photo) that GRJ mentioned earlier is a good performer but kind of spendy (over $1 each?).  As the photo shows, there are options though hard to suggest a specific component without seeing the mounting or space constraints of the particular passenger car. 

I'd think some cars might even accommodate the widely-available 3mm style for less than a penny per LED

red 3mm less than a penny each

 

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  • resistor assortment less than a penny each
  • red leds for marker lights
  • red 3mm less than a penny each

I totally agree with Stan, the resistor assortment is very useful if you don't have a lot of parts around.  I actually bought the surface mount equivalent kit in several sizes for when I'm working on a new design and just need a specific resistor value.  I still have a huge bag of thru-hole resistors from years ago, so I have those covered.

I only use the ceramic LED's when nothing else will fit, many times I can use a 2mm post LED for those applications.  I keep plenty of these on hand in various colors, as well as bi-color and blinking styles.

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  • mceclip0
  • mceclip1
stan2004 posted:

But back to the red LEDs.  

red leds for marker lights 

Another reason you'll need to tune the resistor is there is a substantial difference in brightness (for a given current) between red LEDs.  I've found the ceramic stem type (bottom of photo) that GRJ mentioned earlier is a good performer but kind of spendy (over $1 each?).  As the photo shows, there are options though hard to suggest a specific component without seeing the mounting or space constraints of the particular passenger car. 

I'd think some cars might even accommodate the widely-available 3mm style for less than a penny per LED

 

 

Thanks for the item numbers, more items to add to my Digi-Key favorites list.

Ron_S posted:

...trying it without a resistor would light the red led but nothing on the led strip. 

Right.  Without a resistor, the marker LEDs would siphon ALL the current from GRJ's board and hence extinguish the LED strip.  Adding external resistance limits how much the marker LEDs steal from the strip.  Going the other way, if you add too much external resistance - say, 10K or more, the marker LEDs steal very little...but be unusably dim.

upguy posted:

A few years back you posted the circuit below using  the CL2N3 current limiter with the LED strip lighting instead of the LM317 circuit.  Are there any advantages/disadvantages of one circuit over the other?  Can the dimmer also be used with the CL2N3?

Ron, that was my original method of upgrading the cars, the CL2 puts out a fixed 20ma and is non-adjustable.  The lighting module was my way of rolling all the desirable attributes into one PCB, low power, flicker free operation, DCS compatibility, and intensity adjustment.

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