Re: DCC HO DC Question

Blair & Rasa

Yes, we know that the input may be AC or DC, and that regardless of that
input signal, in at least the Digitrax case, the input is rectified. Yes,
we know that any system that produces AC from DC from AC is going to need
what we generally refer to as "headroom". Digitrax specs 12 to 28 as input
DC, what I am more or less questioning is whether 13.8, or even 12, provided
sufficient voltage "at the track" for satisfactory operation. The latter is
a very subjective consideration, so I guess the upshot is I should just try

The double battery suggestion is a fine one; I'll need yet a third, I guess,
for all the PS12 and other electronics. Alternatively, I guess an inverter
might be a better idea, with the layout wired for 110 VAC. Then I won't
need to make these decisions at all, off-the-shelf equipment will suffice.

-----Original Message-----
From: WiringForDCC@... [mailto:WiringForDCC@...]On
Behalf Of Marcus Ammann
Sent: July 12, 2005 04:45
To: WiringForDCC@...
Subject: RE: [WiringForDCC] DCC HO DC Question

Hi Blair

You can power your DCC systems with DC.
NCE - 18 to 28 volts DC
Lenz - 15 to 18 Volts DC
Digitrax - 12 to 28 volts DC

DCC power at the track is produced from DC that is made from rectifying
the normal AC voltage from your transformer by a bridge rectifier in the
booster. Supplying the bridge rectifier with DC instead of AC will still
provide DC to the booster circuits. It just uses 2 diodes to pass the
DC, instead of the 4 that are used for rectifying the AC.

The bridge rectifier and the electronics that produce the DCC voltage
will require some "extra" volts. For example if you supply the DCC
system 12 volts from a car battery you will only at maximum get say 10
volts. All decoder will work on 10 volts DCC but top speed will
certainly be affected. Sound decoders will start dropping out at 9

So for a DCC system to provide the recommended HO voltage of 14.25
volts, it will require at least 16 to 18 volts DC.

So if you go off the "grid" and have to supply your system with DC then
I would check your system requirements. From the above if you were
operating either the NCE or Digitrax, you could supply them with two 12
volt batteries connected in series to give you 24 volts. You will have
to separate the batteries to charge them with a 14 volt car alternator.

Hope this helps


-----Original Message-----
From: WiringForDCC@... [mailto:WiringForDCC@...]
On Behalf Of Rasa and Blair Smith
Sent: Tuesday, 12 July 2005 11:34 AM
To: WiringForDCC@...
Subject: [WiringForDCC] DCC HO DC Question

For those with a lot more experience. I keep reading comments about
VDC not being enough to power DCC systems for HO, because you "dont get
enough speed out of the locos". Now, when I think about it for not very
long, it seems to me that that implys running the units at full throttle
being unsatisfied with performance. So what voltage DC is required to
achieve full performance? Yes, I realize that we have to assume a few
things, like the voltage drop to the farthest corner of the layout, etc.
etc, but ignoring those factors for a moment, what input voltage DC
we strive for to get satisfactory DCC performance?

If 13.8 VDC is satisfactory as long as we aren't looking for slotcar
performance, then the next question becomes will a DCC system perform
satisfactorily from an automobile electrical system? With and without
alternator charging system, or only when the car is running?
12 VDC is the minimum input, right? Or is that optimistic?

I ask all of this because there is a significant chance I am going to
to go off-grid in my next abode, and I expect 12 Volts will be part of
life at that point.

Blair Smith
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