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I just received a DCC Specialist On Guard circuit breaker and Auto
Reverser OG-AR. While reading the instruction (yes I do read the
instructions first) I found an interesting recommendation. I am not
an electrical engineer but I think the guys that make and sell these are,
so I tend to follow the manufacturer’s recommendation for their
product. NOT all manufacturers recommend this.
Quote from DCC specialist helpful hints:
“For reverse sections, we recommended that the gaps be staggered about
1/8". Perfectly aligned gaps may reduce performance.”
As to gaps, on my layout the gaps for reverse sections are wide enough
and filled so that one metal wheel will not trip the reverser, I have
explained in past posts why I need this feature. It has to be the
continuity of a powered truck that trips the reverser. I.E. The
leading axle and trailing axle are wired together by pick-up. When the
leading axle is in one section the trailing axle is in the other and
forces the reverser to trip.
Example in”What happens to a train when the power reverses in an
automatic reversing section?”
Each layout and the needs of the user may vary and there is always more
then one solution.
At 12:44 AM 3/10/2014, you wrote:
there a rule of thumb as to how wide a gap should be. I'm modeling in
1:20.3 now referred to as F/Fn3 by
Gap width is not
related to scale. Gaps serve four electrical purposes:
separate the track into blocks for purposes of detection (signaling,
isolate a reversing section from a non-reversing section,
the railroad down into manageable sections for trouble shooting, and
case of DCC, separate the railroad into booster power districts and
circuit breaker districts.
In all of the
above cases, the narrowest of gaps will suffice for purposes of
separating one block from the next – a razor saw, an insulated rail
joiner, or the thinnest cutting wheel in your Dremel is more than
sufficient. However, it may be better to use a slightly wider gap
in order to place material in the gap to keep the rails from shifting and
closing the gap.
Gaps need to be
relatively small so that a wheel bridging that gap triggers your DCC
reversing section (That’s how they work – they detect the short and
reverse the phasing of the reversing section before your DCC Booster
senses the short and shuts down).
There is no
benefit is off setting your gaps for reversing section. The first
wheel to cross the gap triggers the reversing process – anything after
that is irrelevant. The circuitry doesn’t care if one or both
wheels span the gap(s) at the same time – the sensing of the short
triggers the reversal.