LocoNet RailSync pair


[I have asked this from Allan directly but he wished me to forward it
to this yahoogroup. As my membership here got stuck into pending I
have already asked the same question through Loconet_Hackers. Sorry
for sort of cross-posting /Psi]

From Allan Gartners "Wiring for DCC" web site I came across this:


"-- Wire 1 and 6 is the LocoNet signal. -- -- Digitrax literature and
their website will lead you to believe that these are duplicated
signals. They aren't. The signal is actually only present on one of
the wires. The signal gets to the other wire when a throttle or the
radio receiver are plugged into the network. Unless you have a break
before you reach these "bridging throttles," it is unlikely you will
ever need to know this. I mention here because the Digitrax
literature is misleading and a few people have suffered many lost
hours because of this. --"

As english is not my native language I must have misinterpreted the

From the text I (mis-?)concluded that LocoNet RailSync coming from
the Command Station should have either pin 1 or 6 disconnected or
grounded, and only one of the pins will carry the copy of DCC signal,
and that throttles or panels such as UP3 or UP5 would somehow connect
the pins 1 and 6 together.

I had previously got the impression from the past that pins 1 and 6
carry low current DCC rail copies having signal levels of 0 volts to
7..26 volts related to ground (pins 2 and 5), and as the pins 1 and 6
are copies of the rails, they should be in opposite phase: if pin 1
is lo then pin 6 is hi and vice-versa. As and if the RailSync pins
have opposite phases, combining the two with two diodes yelds "almost
clean DC" in respect to Signal ground (pins 2 and/or 5). As DIY
LocoNet throttles are powered from pins 1 and 6 through diodes and
grounded to pins 2 and 5 it suggests that power is needed from both
wires to get near pure DC and that the pins 1 and 6 should not be
connected together.

Boosters could get their signal by connecting an optocoupler across
pins 1 and 6 (either way -- phase shift) or between 1/6 and 2/5
(Optocoupler LED anode facing 1 or 6 -- also causing phase shift).

UP3 and UP5 panels will cut the RailSync data connection between all
but the rear jack by connecting the RailSync pairs of the rear jacks
together with diodes (like it is done within the DIY throttles) and
feeding almost pure DC to front and side jacks or even let external
power source feed the all but rear jack's pins 1 and 6.

So -- to my understanding -- pins 1 and 6 in command station are
_both_ carrying signal but in opposite phase and hence are not and
must not be tied together, and panels such as UP3 and UP5 will --
through diodes -- ruin the Railsync data from the front (and side)
jacks and replaces RailSync signal with DC generated form RailSync
pair and/or external power.

Have I misunderstood "Wiring for DCC" explanation or is there a huge
gap in my background info -- or what is wrong?


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