Re: Relay for dead-end wye - no need ...


Jeff Johnston
 

--- In WiringForDCC@yahoogroups.com, "gbw314" <dale.konkol@e...> wrote:

What relay would I use (Radio Shack #?) for a wye track arrangement.
One leg of the wye would have no outlet and will be a yard. Also,
would it matter if the two tracks leading to the the yard are on
differnet blocks?
Dale in Badgerland. <<<<

Dale:

Use a Tortoise switch machine for that tail turnout on the wye, and you won't need to
mess around with extra relays and such. The Tortoise has, built in, a set of contacts
that amount to a DPDT switch. Those contacts are used to power the tail of the wye,
and in this case, the yard beyond.

The contacts are wired so the tail track takes its power from whichever track the
switch is lined for, and the polarity automatically changes to reflect the chosen route.

A caveat: If the entire yard is powered via the Tortoise contacts, such that the polarity
of the wiring changes each time the wye tail switch is thrown, any engines running in
the yard will experience a momentary jerk/stall as the contacts change the track
polarity. If it's something like a staging yard with minimal operation, this may not be
a problem.

Another caution: If you have numerous engines operating in the yard, you may still
want to use the Tortoise to power an auxiliary relay with contacts rated to handle the
power demands of the yard wiring. The Tortoise may have enough power rating, but
I'm not sure.

As for it mattering if the tracks leading in are on separate blocks, I don't think so.

(By the way, this is not just a theory. Bring up almost any DCC wiring discussion and
someone will sooner or later, inevitably say "that won't work because ..." in spite of
the fact that it's a proven system that works in the real world. This is one of those
cases. It's been done, and it works fine.)

Jeff Johnston
SPLCo/MWRy circa Sept 1927

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