Using LEDs with mSD/3 decoders

Welcome Guest! To enable all features please Login or Register.

Notification

Error

Using LEDs with mSD/3 decoders

Options

View

Previous Topic Next Topic

Bryan		#1 Posted : 19 November 2018 06:58:46(UTC) Retweet
Joined: 08/09/2010(UTC) Posts: 211 Location: Bowral, NSW, Australia		Dear All I am converting an old Marklin 37376 BR 101 Electric to a new mSD/3 decoder. The old front LED panel has 3 LEDs in it. The wires coming from it are ORANGE, BROWN/GREEN, YELLOW and GREY. The new mSD/3 has the corresponding wires coming from it also. Do I put a 1K resistor in line on the ORANGE lead to reduce the voltage to the LED panel as this is the return cable I think. I have done a drawing to show what I have. Or do i put a resister in line on the BROWN/GREEN, YELLOW and GREY wires separately. Any suggestions appreciated. Regards Bryan
		WWW

User Profile View All Posts by User View Thanks


	Wish to join the discussion?! Login to your marklin-users.net community \| Forum account or Register a new forum account. Or Connect via Facebook

jerdenberg		#2 Posted : 19 November 2018 08:45:29(UTC) Retweet
Joined: 10/01/2005(UTC) Posts: 1,011 Location: Den Helder, Noord-Holland		If you put a resistor in the return line only, the brightness of the LEDs will vary with the number of LEDs switched on. If you want the LEDs to have constant brightness, each LED should have its own resistor. Jeroen
		Figomima division, UP; mostly figment of my imagination yet.
		WWW
2 users liked this useful post by jerdenberg		ktsolias, TEEWolf
User Profile View All Posts by User View Thanks

Bryan		#3 Posted : 19 November 2018 15:41:46(UTC) Retweet
Joined: 08/09/2010(UTC) Posts: 211 Location: Bowral, NSW, Australia		Dear Jeroen Thank you for the reply. Just one question, is the resistor always a 1000 ohms value when using a Marklin LED or LEDs with a Marklin decoder. With a multiple Marklin LED ( times 3) as in this case we have 1 return and 3 supply wires. Therefore each of the 3 supply cables wil have a 1000 ohm resistor in line to drop the voltage down for each LED light segment. We thus use 3 inline resistors. It is really important to get this right as if too much voltage on any of the supply wires will wreck the LED. Does anyone know the maximum voltage of a Marklin LED. Standard LEDs are about 2.2 volts I think. The supply out of the decoder is 19.2 volts. Best regards Bryan
		WWW

User Profile View All Posts by User View Thanks

H0		#4 Posted : 19 November 2018 16:09:17(UTC) Retweet
Joined: 16/02/2004(UTC) Posts: 15,266 Location: DE-NW		Check the resistors on the original decoder board. They might well be 2k2 (2200 ohms) or even higher. In the 36xxx hobby locos the resistors are 5k6. I converted some Märklin BR 101 locos to white LEDs using the spareparts from current models. I added 10k in line with the original resistor to reduce the brightness. The board you have has 7 LEDs: three yellow LEDs in series for the main lights, two yellow LEDs in series for long distance headlights, two red LEDs in series. 1000 ohms is enough to protect the LEDs, but lights could be too bright.
		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

2 users liked this useful post by H0		ktsolias, Bryan
User Profile View All Posts by User View Thanks

ktsolias		#5 Posted : 19 November 2018 18:39:32(UTC) Retweet
Joined: 01/05/2016(UTC) Posts: 610 Location: Athens		The brightness of the LEDs can be adjusted in mSD/3 decoders through programming either from CS3 or with 60971 device. Of course the 1kΩ is absolutely necessary Costas

1 user liked this useful post by ktsolias		Bryan
User Profile View All Posts by User View Thanks

jerdenberg		#6 Posted : 19 November 2018 21:48:15(UTC) Retweet
Joined: 10/01/2005(UTC) Posts: 1,011 Location: Den Helder, Noord-Holland		Originally Posted by: ktsolias The brightness of the LEDs can be adjusted in mSD/3 decoders through programming either from CS3 or with 60971 device. Of course the 1kΩ is absolutely necessary Costas I can imagine it is simpler/more convenient to adjust the brightness by varying the output of the decoder, but in this case, where resistors have to be added anyway, I would leave the outputs as are, and determine the desired resistor value empirically (starting from the absolute minimum; 19.2 V with a 1k resistor would give about 17 mA through the LED, which sounds quite high/very bright to me). By using different resistors you can also give lights with different functions the corresponding brightness (I did that for the headlight vs number boards in an Alco PA). Jeroen
		Figomima division, UP; mostly figment of my imagination yet.
		WWW
1 user liked this useful post by jerdenberg		dickinsonj
User Profile View All Posts by User View Thanks

kiwiAlan		#7 Posted : 19 November 2018 23:10:17(UTC) Retweet
Joined: 23/07/2014(UTC) Posts: 8,107 Location: ENGLAND, Didcot		Originally Posted by: jerdenberg I can imagine it is simpler/more convenient to adjust the brightness by varying the output of the decoder, but in this case, where resistors have to be added anyway, I would leave the outputs as are, and determine the desired resistor value empirically (starting from the absolute minimum; 19.2 V with a 1k resistor would give about 17 mA through the LED, which sounds quite high/very bright to me). By using different resistors you can also give lights with different functions the corresponding brightness (I did that for the headlight vs number boards in an Alco PA). Jeroen In my experience, for white LEds 17mA will be 'burn your eyes out' bright. You will definitely need to turn these down. However 17mA may be fine with red LEDs.

1 user liked this useful post by kiwiAlan		Bryan
User Profile View All Posts by User View Thanks

H0		#8 Posted : 20 November 2018 08:28:38(UTC) Retweet
Joined: 16/02/2004(UTC) Posts: 15,266 Location: DE-NW		Originally Posted by: kiwiAlan In my experience, for white LEds 17mA will be 'burn your eyes out' bright. You will definitely need to turn these down. However 17mA may be fine with red LEDs. When converting BR 101s to new LED boards, I add 10k for both the white and the red LEDs. The new red LEDs used by Märklin are much more efficient than the old ones. I do the opposite of the conversion discussed here: I replace the LED boards while keeping the original DIP switch decoder - the decoder does not support dimming of function outputs. In some locos where I replaced yellow LEDs with white LEDs I dimmed the function outputs to 25/255 for the headlights. But, as Jeroen wrote, when I have to add a resistor anyway, then I prefer a resistor that is closer to the required value.
		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

2 users liked this useful post by H0		dickinsonj, skeeterbuck
User Profile View All Posts by User View Thanks

Users browsing this topic
Guest

Forum Jump

You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.