LED's and 470 ohm resistors

[Cobra GT]

I am hooking up a reverse light in a trainline gp9m and I tried it with and without the resitor and it worked both ways I also tried it on a 12v power supply both was and it also worked. I went ahead and put the resistor just to be safe. Also the gp9m has tsunami 1000. Thanks.

 

[wright2626]

some leds have a resistor "built in", so they work on 12 volts, or the board in your loco is assembled to only have a 3 volt output.

 

[Cobra GT]

So I don't need a resistor using tsunami tsu 1000 as it puts out 3v for back up light?

 

[wright2626]

as long as the led you are using does not have a resistor built in. i would check the terminals with a voltmeter first.

 

[Mark R.]

You must have gotten ahold of a 12 volt LED (built in resistor) as the TSU-1000 puts out 12 volts on the function outputs.

Mark.

 

[wright2626]

as far as i know, just about all of the soundtraxx boards are either 12 or 1.5 volt light outputs.

 

[Cobra GT]

They are radio shack leds 3v I think I put a resistor any way and it is bright enough the. Board is worth than the loco trainline gp9m. I ordered the decoder and speaker when I ordered my power cab. Thanks guys for your help. Peace.

 

[dinwitty]

you need a voltmeter to test things out. be safe and use the resistor, if the decoder goes on the fritz the LED is safe. If the LED doesnt seem bright enough for you you can find smaller resistors to use, they are quite cheap.

 

[gnm109]

Hello. First post here. I tried to edit my profile to show my location (Northern California) but it tells me that I can't do that. LOL.

I use lots of LED's on my indoor G Scale RR which is in my barn on the second floor. I have tested the smaller ones with an accurate voltmeter and they turn on at approximately 1.7 VDC. I like to run them around 20 ma where max. ma is about 30 ma. Therefore, the formula that I use based on Ohm's law assuming 12 VDC max. is:

I = E-1.7 So: 20 ma = 12-1.7 or 10.3 VDC over R 515 Ohms

Some time ago I converted my LGB 2060 Schoema Diesel to superbright white LED's for both head light and tail light. I left the original bulb in the cab since it's on all of the time that the locomotive is running. I had a drawer full of 560 ohm resistors so I used them for the head and tail lights and they work nicely.

Some of the LED's on my layout have been running for more than 20 years of intermittent use. I've yet to have one burn out. I'm sure that most here use similar calculations but I thought I would share.

This is a very nice forum.

 

[Ken G Price]

Hello. First post here. I tried to edit my profile to show my location (Northern California) but it tells me that I can't do that. LOL.

This is a very nice forum.

Welcome aboard.

Go to the top of the forum page and click Your Settings link, not My Profile.
Every thing you want to add or change should be in links on the left side of the settings page.
One on the left will show boxes with one saying My Settings. You can edit from there.

 

[gnm109]

Welcome aboard.

Go to the top of the forum page and click Your Settings link, not My Profile.
Every thing you want to add or change should be in links on the left side of the settings page.
One on the left will show boxes with one saying My Settings. You can edit from there.

Thanks. I'll do that.