dcc gp40 leds?

[union pacific 844]

hi want to replace the leds  on the dcc Bord with brighter leds do i need resistors?

[union pacific 844]

why no replays on this?

[jonathan]

UP,

You are not being ignored.  Either no one knows the answer, or you weren't specific enough with your question.

Typically, the light resistors are built into the PCB board for the lights.  Perhaps no one knows what type of LED is used on the GP40.  There is no diagram for the DCC equipped GP40 on the website.  You may be the first to attempt changing out the LEDs on a GP40.

When upgrading electrical work, many folks remove the PC board and build in their own wiring and light resistors.

On my Bachmann locos, I find it's not the resistor or light source that's the problem. It's the placement of the bulb/LED.  I tend to move them closer to the headlight lens and that solves the brightness issue.  Food for thought.

Regards,

Jonathan

[union pacific 844]

ok thanks

[JRG1951]

UP
LEDs can be purchased in various brightness levels. Generally the resistor requirement does not change with the different LEDs. Most LEDs are forward biased from 1.7 to 2.4VDC. If you select an LED with a VI in this range the existing Resistors should work.

The brighness of a LED is expressed in MCDs (millicandela (mcd)= thousandths of a candela). The higher the MCD number the brighter the LED.

I prefer Yellow LEDs to White LEDs, and I have found that a medium brightness is better than a High brightness for loco headlights. You may want to buy an assortment and draw your on conclusions  They are usually pretty cheap, just tag them and make notes, because most LEDs look alike

Jameco electronics is a good place for electronic parts.

http://www.jameco.com/webapp/wcs/stores/servlet/StoreCatalogDisplay?storeId=10001&catalogId=10001&langId=-1&rfr=1

Information on LEDs can be found here

http://en.wikipedia.org/wiki/LED_circuit

Regards
John
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[richg]

Just get your multimeter out and measure the resistance used. My experiences so far show the Bachmann uses a resistor with a larger value than many of us use.
Many pople use 1k and maybe down to say 510 ohms.
Most led's in locos today are 20 ma max and a 1k resistor allows about 9 ma. Bachmann sometimes uses over 2k. I have done some measuring. For one or two LED's don't worry about voltage. Some people make this very complicated for one or two LED's.
I have a couple locos with three LED's and one, 1k resistor. Headlight and two number boards of a Tsunami decoder.
Some who use a super bright LED have to use a higher value than 1k. You just have to know what you are doing.
My measurements below.

Measured with 12.2 VDC supply using 20 ma max current LED's.
Resistor      Current
1000 ohm    9.0ma
750 ohm     12.45ma
680 ohm     13.12ma
510 ohm     16.25ma

If you want to work at the component level, you should have and know how to use a multimeter.

Rich
Rich