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Offline DaleSchultz  
#1 Posted : 18 November 2020 19:19:08(UTC)
DaleSchultz

United States   
Joined: 10/02/2006(UTC)
Posts: 3,511
I have made a fairly extensive web page on the use of LEDs in models, including interior train lighting.

https://cabin-layout.mixmox.com/2019/10/modelling-with-leds.html

Hopefully it is in a digestible form for anyone who is starting without any knowledge of how they work. More experienced modellers may be able to get something out of the later content too....


LED light strip schematic
Dale
Intellibox + own software, K-Track
My current layout: https://cabin-layout.mixmox.com
Arrival and Departure signs: https://remotesign.mixmox.com
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Offline applor  
#2 Posted : 18 November 2020 21:47:38(UTC)
applor

Australia   
Joined: 21/05/2004(UTC)
Posts: 1,567
Location: Brisbane, Queensland
That's a lot of time and effort compiling that article Dale and very thorough - amazing job!
modelling 1954 Germany (era IIIa)
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Offline Ross  
#3 Posted : 18 November 2020 22:43:44(UTC)
Ross

Australia   
Joined: 25/09/2006(UTC)
Posts: 750
Location: Sydney, NSW
Hi Dale,

Great effort on the use of LED's.

You mention component size and a correction is needed as a 0402 size is in thousands of an inch so 40 thou x 20 thou is equal to 1mm x 0.5mm size component.

The other aspect of using LED's is to consider the viewing angle of the LED and also the colour temperature (warm white, cool white) etc.

Hope the above comments help.

Ross
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Offline davo_vespa  
#4 Posted : 19 November 2020 01:34:21(UTC)
davo_vespa

Australia   
Joined: 04/05/2017(UTC)
Posts: 41
Location: Victoria, Melbourne
Excellent article, thank you Dale.

I have been making extensive use of LED's on my layout with the dreaded flickering. I remember reading an earlier article of yours setting out the circuit for the rectifier but found the attached on EBay and they work a treat. Cheaper and easier than building yourself,

https://www.ebay.com.au/...arJS~&frcectupt=true

Happy Days, David
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Offline river6109  
#5 Posted : 19 November 2020 03:09:02(UTC)
river6109

Australia   
Joined: 22/01/2009(UTC)
Posts: 13,266
Location: On 1965 Märklin Boulevard just around from Roco Square
I've been using 0402 smd leds and its a task which is sometimes pure luck to fit to locos headlights by the right polarity, unfortunately I've found if you buy a loco and it hasn't got sound with other words the loco has lesser components such as a sound decoder they leave out sometimes the high beam option, the led circuit board has the provisions for it but haven't added them to it as well the interior cab light but again the provisions are made on the main circuit board.

John
https://www.youtube.com/river6109
https://www.youtube.com/6109river
5 years in Destruction mode
50 years in Repairing mode
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Offline DaleSchultz  
#6 Posted : 19 November 2020 03:39:39(UTC)
DaleSchultz

United States   
Joined: 10/02/2006(UTC)
Posts: 3,511
Originally Posted by: Ross Go to Quoted Post
Hi Dale,

Great effort on the use of LED's.

You mention component size and a correction is needed as a 0402 size is in thousands of an inch so 40 thou x 20 thou is equal to 1mm x 0.5mm size component.



Thanks Ross! I have corrected that... any idea why 0402 is in thou and all the others are tenths of a mm ??



Dale
Intellibox + own software, K-Track
My current layout: https://cabin-layout.mixmox.com
Arrival and Departure signs: https://remotesign.mixmox.com
Offline DaleSchultz  
#7 Posted : 19 November 2020 03:48:15(UTC)
DaleSchultz

United States   
Joined: 10/02/2006(UTC)
Posts: 3,511
Originally Posted by: davo_vespa Go to Quoted Post
Excellent article, thank you Dale.

I have been making extensive use of LED's on my layout with the dreaded flickering. I remember reading an earlier article of yours setting out the circuit for the rectifier but found the attached on EBay and they work a treat. Cheaper and easier than building yourself,

https://www.ebay.com.au/...arJS~&frcectupt=true

Happy Days, David


Thanks Dave,
interesting little device. I am not sure why they advertise the input to only 15V but I suspect the capacitor is only rated for 25V.
Any idea what voltage you are getting out of them when supplied with your digital current? (or are you running analog?)

If the input exceeds 17V the cap might let go....

Have you seen any that allow a higher input? (>= 20V)


What would be really nice is a rectifier + buck converter all in one.....
Dale
Intellibox + own software, K-Track
My current layout: https://cabin-layout.mixmox.com
Arrival and Departure signs: https://remotesign.mixmox.com
Offline Ross  
#8 Posted : 19 November 2020 04:28:02(UTC)
Ross

Australia   
Joined: 25/09/2006(UTC)
Posts: 750
Location: Sydney, NSW
Hi Dale,

Design of electronic components in the early days started with imperial measurements (USA) now there is a mix with metric size components. I always refer to the data sheets for the true size and use.

Regards
Ross


Originally Posted by: DaleSchultz Go to Quoted Post
Originally Posted by: Ross Go to Quoted Post
Hi Dale,

Great effort on the use of LED's.

You mention component size and a correction is needed as a 0402 size is in thousands of an inch so 40 thou x 20 thou is equal to 1mm x 0.5mm size component.



Thanks Ross! I have corrected that... any idea why 0402 is in thou and all the others are tenths of a mm ??





Ross
thanks 1 user liked this useful post by Ross
Offline davo_vespa  
#9 Posted : 19 November 2020 09:23:24(UTC)
davo_vespa

Australia   
Joined: 04/05/2017(UTC)
Posts: 41
Location: Victoria, Melbourne
Originally Posted by: DaleSchultz Go to Quoted Post
Originally Posted by: davo_vespa Go to Quoted Post
Excellent article, thank you Dale.

I have been making extensive use of LED's on my layout with the dreaded flickering. I remember reading an earlier article of yours setting out the circuit for the rectifier but found the attached on EBay and they work a treat. Cheaper and easier than building yourself,

https://www.ebay.com.au/...arJS~&frcectupt=true

Happy Days, David


Thanks Dave,
interesting little device. I am not sure why they advertise the input to only 15V but I suspect the capacitor is only rated for 25V.
Any idea what voltage you are getting out of them when supplied with your digital current? (or are you running analog?)

If the input exceeds 17V the cap might let go....

Have you seen any that allow a higher input? (>= 20V)


What would be really nice is a rectifier + buck converter all in one.....


Gu’day Dale,

I have an analog layout and the light circuit is powered by a Märklin 6003 transformer. On a mixed (incandescent + LED) circuit I measured the in/out voltage of the rectifier with my Fluke multimeter at 17.15V AC / 22.5V DC.
I purchased the 6V-16V model (they also have a 6V-32V model) and whilst on the high side, it seems to work fine with my mixture of incandescent, LED strip and SMD 0603’s.

Cost me AUD 14.86 for 10 delivered.....bargain BigGrin

Happy Days, David
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Offline kiwiAlan  
#10 Posted : 20 November 2020 13:48:59(UTC)
kiwiAlan

United Kingdom   
Joined: 23/07/2014(UTC)
Posts: 5,397
Location: ENGLAND, Didcot
Originally Posted by: DaleSchultz Go to Quoted Post
Originally Posted by: Ross Go to Quoted Post
Hi Dale,

Great effort on the use of LED's.

You mention component size and a correction is needed as a 0402 size is in thousands of an inch so 40 thou x 20 thou is equal to 1mm x 0.5mm size component.



Thanks Ross! I have corrected that... any idea why 0402 is in thou and all the others are tenths of a mm ??



They are all quoted in two sizes, metric and imperial, so a 1206 component in imperial is a 3216 in metric.
See https://olimex.wordpress.com/201...tric-imperial-confusion/ for a conversion table. it gets confusing when there is an 0402 metric size and also an 0402 imperial size.

And also be aware that 0402 components and smaller are considered a health hazard, and a face mask should be worn, as it is far too easy to breath in one of them resulting in asbestosis type symptoms (miners lung, et al).
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Offline H0  
#11 Posted : 20 November 2020 14:35:27(UTC)
H0


Joined: 16/02/2004(UTC)
Posts: 13,838
Location: DE-NW
Originally Posted by: DaleSchultz Go to Quoted Post
I am not sure why they advertise the input to only 15V but I suspect the capacitor is only rated for 25V.
Any idea what voltage you are getting out of them when supplied with your digital current? (or are you running analog?)

If the input exceeds 17V the cap might let go....
A digital track voltage up to 24 V should be no problem for a 25 V capacitor. But a Märklin transformer with 16 V AC nominal voltage could be a problem. And the reversing voltage will be far beyond the specification.


Originally Posted by: DaleSchultz Go to Quoted Post
any idea why 0402 is in thou and all the others are tenths of a mm?
I used many 0603 to replace the factory-installed yellow LEDs in Märklin locos - and those are imperial units, too.



Regards
Tom
---
"In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS
UserPostedImage
Offline mario54i  
#12 Posted : 20 November 2020 15:45:57(UTC)
mario54i

Italy   
Joined: 28/03/2007(UTC)
Posts: 211
Location: Torino,
Originally Posted by: DaleSchultz Go to Quoted Post
any idea why 0402 is in thou and all the others are tenths of a mm ??


There are millions of components with imperial size, not just 0402 LEDs.
In electronics I've always heard of mils for 1/1000 of inch, not thou. Most ICs have 100 mils or 50 mils pitch.
Metric size is relatively recent.
Offline kiwiAlan  
#13 Posted : 20 November 2020 16:50:34(UTC)
kiwiAlan

United Kingdom   
Joined: 23/07/2014(UTC)
Posts: 5,397
Location: ENGLAND, Didcot
Originally Posted by: mario54i Go to Quoted Post

In electronics I've always heard of mils for 1/1000 of inch, not thou. Most ICs have 100 mils or 50 mils pitch.
Metric size is relatively recent.


Metric sizes have been around a long time - many Japanese connectors are 2.5mm pitch, not 2.54mm (0.1") which mucks things up on large connectors. You get away with it on small connectors where hole sizes are large enough to soak up the 0.04mm per pin difference.

While mils have routinely been used as an alternative to thousandths of an inch in many countries, there are also engineers in countries that use both imperial and metric units that use mils to mean millimeters - and I have had situations where it is NOT obvious through context if they mean metric or imperial units, and that includes talking with people from any North American country.

And as to ICs, most fine pitch ones use metric units for the pin pitch, the SO- series SMD packages are the smallest that I can think of with imperial based pin pitch of 0.05". There are a lot of ICs like those used in phones which are 0.5mm or 0.4mm pin pitch.
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