RS Part Number in "DCC Corner" ?

[Anonymous]

Hello. In the November DCC Corner: Wiring a DCC turntable.
The part number given, 276-085, for the light emitting diode with built-in resistor resolves to the following part at www.radioshack.com

" Green LED with Holder $1.99 Brand: RadioShack Catalog #: 276-085 Model: 276-085
Typical MCD is 22. Typical wavelength is 555nm. Lens size is 6mm. Green lens color. Viewing angle is 45°. 15mA (max). Typical Voltage is 12, with a maximum voltage of 12.9V. Comes as package of 1. Mfg hole diameter is 3/16".

No mention is made of a built-in resistor. IS THIS THE RIGHT PART ? Doesn't DCC put up to 18v on the rails ?

Thanks.

[Anonymous]

Since no one esle has answered, that LED would have a built resistor (or something) as most LEDs max at about 5vdc. Dcc puts about 12 volts into the rails as usable power. The voltage may appear higher than that with a VOM, but that's due to the pulse and bipolar nature of the signal on the track. As to it being "the right" part only the author could answer that for sure, but it appears to me that it most likely is. FRED

[dpopp]

Hello and thanks for the question.

After talking with Mike Polsgrove, the columnist, he said he simply stopped in to his local Radio Shack looking for an LED and found that one with a built -in resistor. The part number (276-085) is straight from the package.

As for DCC track voltage, that has been a greatly debated issue as of late. The default voltage for HO scale should be 12-14 volts, but that the value depends upon the system and its booster power supply. If you are using a system with an 18 volt supply, you will want a different resistor for your LED.

I hope that helps and best wishes on your DCC endeavors.

Sincerely