Re: Hornby zero1 & DCC

Mark Gurries

I have operated my large layout by zero 1 for years with no problems
and underestand that it operates by a analog signal transported on a
20volt dc supply to the track which is now obsolete. and IS NOT DCC.

To change over would cost over £1000 with ZTC they say that their 511
controller will operate in zero1 mode and DCC but it has to be one or
the other no both
At the moment I can double-head & bank or control 3 or 4 locos at once
useing my 3 slave units
to do this with DCC would need 511 master extra power boosters and
slave units as I understand it plus all the hornby decoders changed
am I missing something or is this correct?
cheers clive larby
I am not familiar with Hornby Zero system and their exact terminology.


Decoder: A circuit board that is installed in a engine/loco that drive
a motor and control light functions. More advance versions have sound.
Typically the size of a standard decoder varies with the power rating of
the decoder. Decoders with current rating up to 4 amps each are

Booster: The number of power boosters needed for DCC will depend on the
number of loco's ACTIVLY RUNNING at the same time and how much current
each one draws. If a locomotive is stopped and sitting on a track, it
does not draw any power worth worry about. Boosters up to 10Amps are
available. Typical version are about 5 amps.

Power Districts: A section of track or tracks with it own circuit
breaker protection. A short in a one power district will NOT shut down
any other power districts. Today there are "DCC circuit breaker"
products that will allow one to share a single booster covering multiple
power districts at the same time. It is much more cost effective than
buying a booster for each power district. Lots of unused power and
very expensive.

DCC does not have any concepts of slave. Decoders are small enough to
fit down to Z scale. The point is that a DCC decoders should fit
directly into each locomotive eliminating the need for slave
locomotives. I suspect that DCC decoders are much smaller than you
hornby zero 1 decoders.

So to properly size you power needs, one needs to consider

1) Number or actively rolling locomotives on the layout at the same
time. Locomotive that are stopped on the tracks do not consume power of
any consequence. Be realistic about this.

2) The typical (not peak) motor current rating of the locomotive. You
can measure this by measuring the locomotive DC current at full speed
with the wheels spinning on the track. Hold the loco by it coupler when
you do this. Total all the current and divide by the number of loco you
measured. This will be your average current per loco.

3) The number of power districts you need to allow smooth operation
tolerant of a short circuit due to derailment. Think geographically or
activity level wise such as a yard or staging track area. Each major
yard should be its own power district seperate from the main line. If
you have lots of main line or double track, maybe it should be broken up
into small districts too.

Multiply Item #1 by Item #2 and that is the minimum current you need to
run the entire layout. Take that number and divide it by the booster
current rating and round up to a whole number. That is the number of
boosters you need.

Divide the layout into zones such that there will be a typically an even
number of trains in each zone at any given time. Assign a booster to
cover each zone and then divide the zone up into power districts using
DCC circuit breakers as required.

Note: If you have lighted passenger cars, they can easily consume as
much as or more current than a locomotive. You must factor that into
you power calculation for boosters and zones.

For more information about wiring and more, consult the wiring for DCC

Best Regards,

Mark Gurries
Linear Technology
Power Supply & Battery Charger Applications Engineer/Manager
Model Railroad Club and NMRA DCC presentations are at:
Audio Enthusiast (Love SAE equipment)

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