The loop
MUST be a "clean" loop. This means there is only one turnout
for entry and exit to and from the mainline. You're allowed to have
sidings or yards within the loop as long as there is no other way
out of the loop except for the turnout where you enter the loop. If
there is another way out of the loop to the mainline, then it is not
a "clean" loop and it will require an auto-reversing unit
of some kind.
This information is specifically for controlling
the polarity of the loop or wye where the turnout to the loop or dead-end
leg of the wye is controlled by a 2-wire twin-coil turnout machine.
If you're using a stall-motor or 3-wire twin-coil machine, other methods
must be used. Note: a twin-coil machine
is one that requires a momentary application of power (usually with
a push button) and has a definite snap to one side or the other.
This information is also aimed using
a Digitrax DS54 turnout decoder to control a 2-wire twin-coil turnout
machine, which in turn controls the polarity of a reverse section.
The methods presented here are but a few variations of what can be
done with a variety of components, and can be adapted for many other
uses for other systems and purposes. You're welcome to adapt this
information for your own use if you can do it yourself, but we do
not have the time and resources to entertain solutions for anything
but Digitrax Command Control.
With that said, and if you're still
with me, let's continue.
There are several ways to do this
- we'll present four, of which many variations can be derived. There
is no one best way due to the fact that not all 2-wire twin-coil machines
are alike and not everybody's situation is the same. I don't use twin-coil
machines myself, don't know of all the different ones that are available,
and don't know how much current each one takes, so don't call up to
ask us for any of that information - ask the manufacturer of the machine
you have.
A 2-wire twin-coil machine requires
polarity reversal to control the direction the motor will snap. Apply
DC polarity one way to snap it one way, and DC polarity the other
way to snap it the other way. About now you're probably saying, but
mine takes AC. No, it doesn't. You may be using AC, but your buttons
or other equipment convert it to DC of the correct polarity for a
2-wire twin-coil machine to work.
So, what's polarity? With DC that
means the "+" and "-" terminals. A battery has
a "+" and "-". When you install a battery, you're
usually instructed to install it with one end in one position and
the other end in the other position. It must be installed correctly
for the device to operate correctly. Reversing the battery reverses
the polarity. With a 2-wire twin-coil machine, if you hook the plus
and minus one way, that's one polarity. Hooking it the other way is
the other polarity.
The DS54's yellow and black wires
provide reversible DC power. When instructed to throw the turnout
it provides DC power of one polarity; when instructed to close the
turnout it provides DC power of the other polarity. BUT, and this
is a VERY BIG but, the DS54 cannot provide enough current out the
black and yellow wires to operate a 2-wire twin-coil machine - it
needs help.
There are two ways to get this help:
1) with a Digitrax DM1-amplifier or 2) with a relay.
The DM1
is a device that plugs directly into the output of a DS54, as shown
below. It uses a set of transistors and the green wire to provide
up to 1/2-amp of current on the yellow and black wires. The other
end of the DM1 is a jack for you to plug the normal output cable into.
This is a very easy way to get up to 1/2-amp of current for 2-wire
twin-coil use. While most twin-coil machines will work with 1/2-amp,
some may require more. Again, don't call us to ask if your machines
take more than 1/2-amp, we don't know. Most vendors won't know this
because the manufacturer doesn't usually published this information.
So, you'll have to ask the manufacturer. |
