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Bought some "cree" LED  bulbs that are "exact replacement" for #1445/1895 bulbs.  Advertised 12-14V,/.185w /270 deg throw/ 40 lumens!  Wont light up the cab on PW FM 2321.  Cant hardly see them in a 6517 bay caboose let alone a F3 2343AA.  Takes 12V to make them "bright".  Even 14V dont make them bright.!   I missed something here.

Bob

 

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External resistors and such are not applicable in this situation as these are exact drop in replacements and require no supporting circuitry.

One of the things that may have been missed in ordering is the beam distribution - some are very focused out the tip where others are focused out the side (and not the tip), and some try to even it out all the way. Can you share exactly what product you purchased and from where?

Last edited by bmoran4
oldtimer posted:

John would you put a link on here showing the actual LEDs you  buy on the bay?  I bought the wrong ones for sure. thanks

Bob

 

John isn't using direct replacements that just screw in/bayonet in to the existing socket. I think that the wide beam of 270° was part of the problem. 20 or 30 degrees is more appropriate.

Were they from the hobby supply or auto illumination?

They were from autoillumination.  They have the "extra bright" ones but they are $9@.  These are supposed to have 40 lumens.  $4@.  I have a light I use for getting to my deer stand in the dark that have 40 lumens.  These lights arent even close.  I wanted to light up the inside of the cabs on F3's and FM's & geeps , cabooses etc.  Plus save about 40W. I thought the 270 deg would be good.  The focused ones would only shine i direction.  Then theres the inverted ones.  Confusing as ^%$#.

bob

oldtimer posted:

They were from autoillumination.  They have the "extra bright" ones but they are $9@.  These are supposed to have 40 lumens.  $4@.  I have a light I use for getting to my deer stand in the dark that have 40 lumens.  These lights arent even close.  I wanted to light up the inside of the cabs on F3's and FM's & geeps , cabooses etc.  Plus save about 40W. I thought the 270 deg would be good.  The focused ones would only shine i direction.  Then theres the inverted ones.  Confusing as ^%$#.

bob

That's disappointing. I don't know if Town & Country's version would be any better. It looks like a build it yourself project now to get the desired result.

How would you like to proceed?

FWIW, I typically use incandescent lighting for cab lights, that's because they do disperse the light uniformly. 

For my LED's I really don't go nuts on the exact light specification for lighting locomotive headlights.  Virtually any 3mm or 5mm round-top LED (focused beam) that I've used has been plenty bright for the job.  The outputs range from 4000 to 18000 MCD, and the actual difference in appearance isn't that great in real life.  If you favor USA shipping (quick), check out eBay: 121729733042.

IMO, lighting the cab of an O-scale locomotive with 40 lumens would look like the sun has just come up in the firebox!  I think that's about 39 lumens too much!

It ain't V= i * R, it is described here: https://en.wikipedia.org/wiki/Diode_modelling

However most every engineer just looks up the spec sheet, finds what the voltage drop at about the current they want, subtract that from the supply voltage, divide by the current they want, which gives a resistor, then take the next stocked (or on-hand) resistor above, then make sure the wattage of the resistor is about half of what is calculated by i * i * R.

I sure hope those LEDs have a built in resistor or they are TOAST. Or, they might have the wrong resistor. Or, you have an LCRU and you are suffering from that issue where the phase is random on start up, but stays stuck for the duration.

I tell people the dirt simple rule of thumb for LED's.  Since a vast majority of the common LED's we are using for O-gauge stuff are rated at 20ma, the computations are simple. 

Take the supply voltage, (assume 12V for rectified track power).  Subtract the operating voltage of the LED from it, (3V for white or blue, 2 for green/yellow/red).  Multiple the remainder by 50, that's the minimum value of the resistor.  In the case of 12V, that would be 9 * 50 or 450.  Since 470 is a standard value, that's the logical choice.  For a single LED at any of the operating voltages we will encounter, you're pretty save with 1/4W resistors.

In many cases, I actually go considerably higher with resistors than the computed minimum value.  Specifically for class lights/markers, I go to the 1K to 2K range, otherwise they're frequently as bright as the headlight, and they looks kinda' stupid IMO.

For the LCRU polarity issue, the easy way to deal with that is a small bridge rectifier and resistor, no more polarity issues.

oldtimer posted:

They were from autoillumination.  They have the "extra bright" ones but they are $9@.  These are supposed to have 40 lumens.

What is their exact part number?  You say 12-14V, takes 0.185 Watts, puts out 40 Lumens.  I couldn't find it on their site as they have so many variations. 

It's surprising to find 40 Lumens at 0.185 Watts... that's over 200 Lumens per Watt which is an efficiency you might get in a research lab...not in a commodity automotive or hobby LED.  A hobby incandescent bulb might put out, say, 5-10 Lumens per Watt.  A hobby LED about 5-10 times that so, say, 50 Lumens per Watt.

Plus when I see something that says 12-14V, it tells me automotive and I've learned (right here on OGR) that there are practices specific to automotive that keep costs down.  For example, can the LED bulbs really operate on AC?  If only DC you lose half your output if you drive it with AC as I assume you're doing.

I found that number a tad suspicious as well Stan, but I figured to wait and see.  For the "bright" LED's I see, I picked one that was 12000MCD, that translates into 1.79 lumens figuring on a 25 degree apex angle, probably typical for round-top LED's.  Since 20ma at 3V is .06 watts, I get 29.8 lumens/watt with that LED.  I have seen some spec'ed at 18000 MCD, so they'd be 44.7 lumens/watt, about what you came up with.  Of course, you aren't dissipating nearly a watt with the LED in question, and 3/4 of that power is going into the resistor!  My guess is the bulb is actually capable of around 1.5-2.0 lumens, a far cry from 40, pretty much what the one I looked at is capable of.

Stan, I hooked them up to my 12V battery in pickup.  No difference in brightness. If you go to their site and click on led for trains.  Its the very first list of  LED bulbs with "cree"  cool white.    Click on "specs"  for info.  I just picked the wrong ones and expected to much.  Trying to reduce some wattage but still have decent lighted cabs.  Used them on 022 swtches and controllers instead.  Work ok there.  Definitly not for locos.  Still like to find a decent LEDs to use in the cabs.   GRJ maybe right about incandesent bulbs for cab lights.  Switched from 1895 3.7W bulbs to 1445  2.5W.  That change saved 14.4W for 12 bulbs, little over 1A.  Better than nothing I guess. Hard to light up PW F3;s and FM's. Lights in "B" units are tuff also.  

bob

oldtimer posted:

...If you go to their site and click on led for trains.  Its the very first list of  LED bulbs with "cree"  cool white.    Click on "specs"  for info.

OK.  I see it now.  It's not just the one you selected but their other LED bulbs have questionable specs.  Kind of makes you wonder how you're supposed to make an informed choice! 

Anyway, if dropping from 3.7W to 2.5W bulbs works for you then so be it.  But in general when switching from incandescent to LED you should be able to drop to less than 1W while maintaining the same brightness.  I know you're looking for plug-and-play bayonet style but if you can find LED bulbs that have multiple LEDs inside you'll get more Lumens/Watt.  That website does seem to have some bayonet style bulbs with multiple LEDs (e.g., what they call matrix 5) but not in the "train" section from what I can tell.

oldtimer posted:

Thanks  Carl.  

bob

The headlight wires are connected to hot(track in) , same as the bayonet bulb and to chassis ground. The other parts needed to power the led are in the bulge that you see in the wires. I just don't know how big the headlamp hole is in the 23xx shell. A drop of white glue can hold it in or hot glue if you have a gun.

I'm thinking I should get LED's that have a voltage rating of 12V.  My track voltage never exceeds 11.5-12V.  The 18V bulbs would be even dimmer than the 14V?  All pretty dang confusing for this old man. It IS hard to teach an old dog new tricks.   Maybe stay "old school".  LOL Thanks for everyones help here.

bob

 

oldtimer posted:

I'm thinking I should get LED's that have a voltage rating of 12V.  My track voltage never exceeds 11.5-12V.  The 18V bulbs would be even dimmer than the 14V?  All pretty dang confusing for this old man. It IS hard to teach an old dog new tricks.   Maybe stay "old school".  LOL Thanks for everyones help here.

bob

 

Bob, you have to remember that when the rating is used for bulbs it is for the maximum voltage that it can handle without reducing the life.

The original 1445-300 is an 18v bulb (from the '50's Lionel repair documents). Using lower voltage incandescent bulbs may provide brighter lights at the expense of shorter life and more heat.

In the case of using LED's, they should be shining brightly before you get the engine to move.

Don't over think it.

Last edited by Moonman

Moonman has good advice above. Follow that and the 'old tricks' you will be fine.

I didn't mean to confuse things, but I run command control and need the 18 volt (or higher) LEDs for anything that I use track power on like track bumpers, sometimes yard lights, etc. and 18 volt+ AC LED bulbs are kind of scarce. I am also getting up there in age and I struggle with some of the 'new tricks' as well. I certainly agree with you about the 'old tricks'!

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