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Caplin		#1 Posted : 01 June 2007 12:28:30(UTC) Retweet
Joined: 23/03/2005(UTC) Posts: 2,497 Location: Denmark		It this a fip or not I have been advised when calculating the series resistor for a white led the current should never exceed 20 milli amps, in fact it should be well below that value to increase the life span of the white led. They wear out! Red leds on the contrary don't wear out I was told, they either work or blow.
		Regards, Benny - Outsider and MFDWPL
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hmsfix		#2 Posted : 01 June 2007 15:11:34(UTC) Retweet
Joined: 06/02/2005(UTC) Posts: 1,383 Location: Darmstadt,		Hi Benny, First time I hear that LEDs (red or white) wear out. To my experience they don't, unless their specs are exceeded. The critical point for any LED is the working temperature of the small Gallium Arsenide semiconductor crystal inside. This must always be kept below say 150 °C. (BTW if you cool down a 20 mA LED with liquid air, it may even withstand 500 mA! Well, liquid air usually is not an option for us model railroaders) Other point is the reverse voltage: take care that the voltage applied to the LED in reverse direction does not exceed 3-4 volts. Regards Hans Martin Edit: Sorry guys, the was an important "not" missing in my reply [:I]. Corrected now.
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Mikael		#3 Posted : 01 June 2007 15:13:40(UTC) Retweet
Joined: 10/09/2004(UTC) Posts: 959 Location: Copenhagen, Denmark		As far as I know, this is correct. White LEDs aren't really white at all. They are blue LEDs that have some sort of phosphorus coating in front of them, which converts some of the blue light to yellow. And blue and yellow mixed gives white. The problem isn't the blue LED in itself, but the coating has a limited lifetime. It gradually wears out when used. Reducing the current, and hence the light, there is less wear on the coating, and it'll last longer. This is mostly a problem with the warm- and golden white types. The cold white should last longer. LEDs of today are so powerful, that running them at 20 mA is way to much anyway, depending on the application of course.
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Caplin		#4 Posted : 02 June 2007 01:49:20(UTC) Retweet
Joined: 23/03/2005(UTC) Posts: 2,497 Location: Denmark		Thank you for your instructive answers. Now probably a lot of members like myself know something more about leds. Now of course we will be wondering if the wear out time has any relevance unless one runs the equipment 24 hours/day.
		Regards, Benny - Outsider and MFDWPL
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David Dewar		#5 Posted : 02 June 2007 13:57:50(UTC) Retweet
Joined: 01/02/2004(UTC) Posts: 7,463 Location: Scotland		I thought if you mix blue and yellow you got green ?? David
		Take care I like Marklin and will defend the worlds greatest model rail manufacturer.
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Mikael		#6 Posted : 02 June 2007 14:51:49(UTC) Retweet
Joined: 10/09/2004(UTC) Posts: 959 Location: Copenhagen, Denmark		Sure, when mixing blue and yellow you do get green...... If it is paint you are mixing. When mixing coloured lights, the results are different. Just like the three primary colours in a TV (light) is red, green and blue, but in a printer (ink) they are cyan, magenta and yellow. It has to do with additive vs subtractive colours. I don't have life expectancy data on any white LEDs right at hand, but I believe the worst ones (warm/golden whites) can be as low as 2-5000 hours at their rated current.
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intruder		#7 Posted : 04 June 2007 02:23:21(UTC) Retweet
Joined: 16/08/2006(UTC) Posts: 5,382 Location: Akershus, Norway		My opinion is that the LEDs normally are too bright for MMR use if you use the rated voltage. So I always increase the resistance of the dropping resistor by one or two steps on the E12 scale. If I calculate it to be e.g. 680 Ohms, I increase it to (820) 1.000 Ohms, or even 1.200 Ohms. That way the intencity is reduced and the lifetime of the LED is increased multiple times.
		Best regards Svein, Norway grumpy old sod
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john black		#8 Posted : 04 June 2007 08:02:07(UTC) Retweet
Joined: 22/04/2004(UTC) Posts: 12,139 Location: New York, NY		Quote: [size=1" face="Verdana" id="quote]quote:Originally posted by intruder <br />I always increase the resistance of the dropping resistor by one or two steps on E12 scale With your CS ... [}:)]
		I hope no one visits a poor Southener's layout in Brooklyn. Intruders beware of Gators. AT&SF, D&RGW, T&P, SP, WP, UP, BN, NYC, ARR, epI-III - analog & digital Marklin Classics only. CU#6021 FX-MOTOROLA DIGITAL SYSTEM. Fast as lightning and no trouble. What else ... Outlaw Member of BIG JUHAN's OUTSIDER CLUB. With the most members, worldwide
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intruder		#9 Posted : 04 June 2007 11:41:52(UTC) Retweet
Joined: 16/08/2006(UTC) Posts: 5,382 Location: Akershus, Norway		Sorry John I forgott to mention that I was talking about home made convertions. E12 is one of the several fixed scale normal resistors follow. If it is an mfx decoder you can reduce the intencity with the CS. The methode was mentioned in a different topic some time ago.
		Best regards Svein, Norway grumpy old sod
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john black		#10 Posted : 04 June 2007 13:20:10(UTC) Retweet
Joined: 22/04/2004(UTC) Posts: 12,139 Location: New York, NY		Thanks, Svein ... How's the weather in Iceland
		I hope no one visits a poor Southener's layout in Brooklyn. Intruders beware of Gators. AT&SF, D&RGW, T&P, SP, WP, UP, BN, NYC, ARR, epI-III - analog & digital Marklin Classics only. CU#6021 FX-MOTOROLA DIGITAL SYSTEM. Fast as lightning and no trouble. What else ... Outlaw Member of BIG JUHAN's OUTSIDER CLUB. With the most members, worldwide
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intruder		#11 Posted : 04 June 2007 15:28:49(UTC) Retweet
Joined: 16/08/2006(UTC) Posts: 5,382 Location: Akershus, Norway		Not so good, John About 7 degrees C, overcast, windy, some rainshowers. But - goof food, nice scenery, hot springs, so the weather is not so important.
		Best regards Svein, Norway grumpy old sod
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john black		#12 Posted : 04 June 2007 15:42:54(UTC) Retweet
Joined: 22/04/2004(UTC) Posts: 12,139 Location: New York, NY		Enjoy whatever is there, Svein. And don't forget to bring a travel layout next time [:p] Please have a look how much HO stuff you can squeeze into a small 14" x 10" toolcase ...
		I hope no one visits a poor Southener's layout in Brooklyn. Intruders beware of Gators. AT&SF, D&RGW, T&P, SP, WP, UP, BN, NYC, ARR, epI-III - analog & digital Marklin Classics only. CU#6021 FX-MOTOROLA DIGITAL SYSTEM. Fast as lightning and no trouble. What else ... Outlaw Member of BIG JUHAN's OUTSIDER CLUB. With the most members, worldwide
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intruder		#13 Posted : 05 June 2007 02:12:50(UTC) Retweet
Joined: 16/08/2006(UTC) Posts: 5,382 Location: Akershus, Norway		Cool, John
		Best regards Svein, Norway grumpy old sod
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David Dewar		#14 Posted : 05 June 2007 02:31:18(UTC) Retweet
Joined: 01/02/2004(UTC) Posts: 7,463 Location: Scotland		Have Marklin will travel David
		Take care I like Marklin and will defend the worlds greatest model rail manufacturer.
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john black		#15 Posted : 05 June 2007 02:35:26(UTC) Retweet
Joined: 22/04/2004(UTC) Posts: 12,139 Location: New York, NY
		I hope no one visits a poor Southener's layout in Brooklyn. Intruders beware of Gators. AT&SF, D&RGW, T&P, SP, WP, UP, BN, NYC, ARR, epI-III - analog & digital Marklin Classics only. CU#6021 FX-MOTOROLA DIGITAL SYSTEM. Fast as lightning and no trouble. What else ... Outlaw Member of BIG JUHAN's OUTSIDER CLUB. With the most members, worldwide
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Bart		#16 Posted : 05 June 2007 02:37:52(UTC) Retweet
Joined: 13/05/2002(UTC) Posts: 676		Svein, have you already spotted the only Icelandic steam locomotive, Minør? On display in Reykjavik harbour. May fit into John's toolcase.... [back to topic mode on] ...which demonstrates the short life span of its white leds, which already were completely blackened at the time this pic was taken.. Edit: Sorry, missed the Reykjavic loco topic here: https://www.marklin-users.net/fo...s&t=7231&whichpage=2
		*Bart
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Rowan		#17 Posted : 05 June 2007 07:34:00(UTC) Retweet
Joined: 09/04/2006(UTC) Posts: 1,278 Location: Brisbane, Queensland		Quote: [size=1" face="Verdana" id="quote]quote:Originally posted by john black <br />Enjoy whatever is there, Svein. And don't forget to bring a travel layout next time [:p] Please have a look how much HO stuff you can squeeze into a small 14" x 10" toolcase ... WOW!
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ulf999		#18 Posted : 09 June 2007 20:16:08(UTC) Retweet
Joined: 12/05/2005(UTC) Posts: 1,908 Location: Stockholm, Sweden		I agree with Rowan!
		Ulf, American HO. www.goldenvalleyroute.com/
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