Manufacurer's decoder output function voltage : LUSENET : Wiring for DCC : One Thread

What are the function output voltages of NCE,Lenz and TCS decoders? Is it dependent on track voltage? I haven't found any of this info on the manufacturer's websites or in their decoder literature.I know the Digitrax decoder output voltage is 12V. The Chicago LSMRA club Digitrax system uses the HO track power setting and I want to get proper resistor configuration for each of these decoder manufacturer's decoders when used on the club layout.

Greg Kelley

-- Greg Kelley (, November 21, 2002


I can't imagine any decoder manufacturer wasting $$ to provide a regulated output for external functions. So, Yes...It is a function of track voltage. The external load is connected simply to the (+) side of a rectified track voltage supply (the NMRA Blue wire). All primary controlled function outputs are pull-down open- collector/drain types that connect the other end of the load to the (- ) side of the same rectifier. When using the recommended 14.25 DCC track volts (for HO scale), the 2 diode drops in the decoder current path will subtract out about 1 volt each. The transistor/mosfet function switch will drop another 0.25 volt or so, leaving...12V for the load.

If the decoder modulates (rapidly switches the load ON & OFF) other average voltages may be obtained. However the current is not limited by the circuit. If you use an LED you must supply your own current limiting resistor to prevent burn-out.

There may be other decoder outputs that require an 'amplifier'. These are likely to be ~+5 V when ON and 0 V when OFF.


-- Don Vollrath (, November 21, 2002.

I completely agree with Don. Normally, no manufacturer provides a regulated output and there really isn't a big reason for them to do so.

For large scale modelers, I thought I should mention that at least one manufacturer has provided a decoder with regulated output. Zimo has a high end model that has a regulated output and you can program what that voltage is. I've never needed it, but I know it's in their catalog.

If you really need it, you might get it into many HO locomotives, but forget diesels that are not "covered wagons." Before deciding you want it, be aware that it cost around $100. (Since I've not used it, I don't know for sure. I have used it's next down cousin that was in the $80 range.)

That is expensive for HO, but other G scale decoders cost $60 or more. So for G scalers, it's a little more tolerable. Besides, after you spent $1000+ for the locomotive, what's another $100? :)

-- Allan Gartner (, November 21, 2002.

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