Booster Network Wiring
INFORMATION #4-1: Function of Each Wire in Digitrax'
Loconet
Wire 3 and 4 is LocoNet power. In Digitrax supplied
cables, these wires are red & green.
Wire 2 and 5 is LocoNet Ground. In Digitrax supplied
cables, these wires are black & yellow. However, in cables purchased
from other sources, these may be different colors.
Wire 1 and 6 is the LocoNet signal. In Digitrax
supplied cables, these wires are white & blue. However, in cables
purchased from other sources, these may be different colors. 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.
Which side of the connector do you start to determine
which wire is number 1? If you think about it, it doesn't matter. The
middle two are always power. The outer two are always signal. The two
between these are always ground - no matter which way you hold the connector!
One of the pins is #1, but which one you don't need to sweat.
RECOMMENDATION #4-2: Put Your Booster Power Transformers
in a Box!
I've only gotten zapped
"bad" twice. It was twice too often! If you have been zapped mildly
and don't think it's any big deal, ask someone who died from electrocution.
I've never been knocked across the room or worse. But I can assure you,
it's isn't any fun and death is definitely possible.
Put your transformer in a metal or plastic box! If you
use metal, be SURE it is grounded.
DO NOT settle for putting on a lot of electrical tape
or heat shrink over the solder terminals of transformers. You may be
shocked, literally, at how easy it is to accidentally have a screwdriver,
or whatever, to find a way to contact the terminal where it meets the
transformer. Also, the enamel insulation on the transformer is literally
that - paint! It is extremely thin, intentionally for maximum transformer
efficiency, and is easily scratched by a tool.
Make sure you use a ventilated box or drill a couple
dozen 1/4" holes. A dozen near the top and a dozen near the
bottom. Put the holes on the sides. Things can be dropped through
holes in the top. Of course, the more holes the better. Don't make them
any bigger than about 1/4".
Digitrax sells
a transformer for general DCC use that is already encased. You
have no excuse to risk your life or someone else's!
RECOMMENDATION #4-3: Use a Separate Network for
your Booster and Throttle Networks
This recommendation applies to any DCC system that has
a network that both throttles and boosters share. The Digitrax Loconet
is such a network. Please note the presence of such a network is does
not make that manufacturer's product undesirable or bad. The Digitrax
Loconet, for example, is a very good system.
Yes. Theoretically, the boosters can be on the same LocoNet
network as the throttles. However, for best reliability, the boosters
should have their own network. Should the boosters "fight" each other,
they will corrupt the data being transferred on LocoNet. This will affect
throttles trying to reach the command station or command station throttle.
If you are using a Chief, just connect one side of the
Chief into your string of boosters and connect your throttle network
into the other side of the Chief. Or, if you want to keep a jack
free on the Chief, buy a 2-way adapter or wall plate at your favorite
home improvement store. The wall plate has a jack for a wall phone plus
several other jacks.
RECOMMENDATION #4-4: Be Sure to Use a Transformer
for Your Booster That Puts Out AT LEAST as Much Current as the Booster
Can.
This is especially important if you have more than one
booster. Having boosters with different capacity transformers can cause
fighting when a locomotive crosses from one booster district to another.
Don't use your old power pack to power a booster.
Many people who get into DCC want to use their old DC
power pack to supply power to their new booster. While you can run
a locomotive this way, I highly recommend that you do not use your
old power pack. The reason is that boosters are typically designed
to put out more power than you power pack is capable of supplying.
Boosters are designed to shut down when they reach a preset limit.
If your power pack isn't able to supply all the power your booster
is designed to, then the booster's shutdown circuitry will never reach
its trip point. What this means is that your booster will not shut
down when there is a short. If your booster doesn't shut down when
there is a short, something on your model railroad will get very hot.
Something will melt; maybe even catch fire. So I highly recommed that
you avoid skimping on the $45 it costs to buy an adequate power source
for your booster.
RECOMMENDATION #4-7: Do Not Run More Than One
Booster Off a Single Power Supply
If you read the documentation that came with your booster,
it may tell you to run each booster from its own power supply. This
is generally the rule. Some may say something different or nothing
at all on the topic. More specifically, do not run multiple boosters
off a single power supply
that is not
fully
capable
of sourcing all the
power that all the boosters attached to it may draw. Example:
If you have two boosters that may draw 5 amps each, if you are using
a common power supply, it must be capable of supplying at least 10
amps.
Always heed your booster manufacturer's instructions.
Some manufacturer's manuals may say do not run multiple boosters off
of a single power supply. Then follow those instructions.
RECOMMENDATION #4-5: Do Not Have A Common Rail
or Common Wire Between Booster Districts
In traditional layout wiring, modelers frequently had
a wire that was common to all blocks. If you wired your DC layout this
way, you may be tempted to use the same approach in wiring for DCC. Do
not do this. Do not connect any of your booster outputs together. This,
too, can be a cause of booster fighting in the form of "ground loops." Worse,
shorts could result if either booster is set to auto reverse.
Please note that the recommendation
below refers to connecting a ground wire between your boosters. In
the recommendation below, you are connecting the grounds of your
boosters together. This is different than connecting your booster
outputs together. The grounds of your boosters should be
connected together.
RECOMMENDATION #4-6: Run a Heavy Ground Wire
Between Your Boosters:
You
should run a heavy wire between the ground (lower gray spring
terminal),
or case, of each booster to the other boosters. It is also extremely
important when doing this, that you disconnect wires #2 & #5
(for Digitrax supplied cables, the black and yellow wires) in your
booster
network.
Adding the heavy ground wire makes
a better common reference connection between boosters than the second
and fifth wire do. Eliminating the second and fifth wire from the booster
network prevents "ground loops." Ground loops can also be a cause of
booster fighting or otherwise corrupting the data on the network.
Remember: Do not use a common
rail between booster districts. This, too, would cause ground loops.
See
4-5 above.
SUGGESTION #4-8: Put Your Boosters Electrically
Central to Their Operating District
Actually, calling this a recommendation is almost an
understatement. It is now almost mandatory that your mount your boosters
central to their power district.
Be sure to read about terminating your bus wires
in the section on track wiring. Modelers have found that when their wiring
from their booster is more than 30' feet long, they have encountered
problems. The worst of which is blowing locomotive decoders.
Therefore, the conventional wisdom is now to locate your
boosters in the middle of the track bus that they serve.
Doing this will allow you to make a track bus that is 60' long. Just attach your
booster to the middle of your track bus.
SUGGESTION #4-9: How Many Boosters Do I Need?
You are buying your first DCC system.
It isn't clear to you how many boosters you will need. Do I need one?
Or two? If you are worrying about this, you don't need to. Just plan
your wiring for 2, but buy only one. You can always buy the second one
later if you run into problems. Nothing is going to blow up if you really
need two. In the mean time, run a pair of #10 wires between your
booster #1 and wiring that will ultimately go to booster #2.
If you are building a club-sized
layout, buy about half as many boosters as you think you will need.
Wire as above. If you need more, buy the ones you need.
SUGGESTION: Resetting Your Booster
What to do if your sound-equipped locomotives are
making it difficult to reset your booster.
Contributed by Don Vollrath, DVollrath@magnetek.com
Problem: New locos with sound decoders have large DC
energy storage capacitors for operating the sound system. (soundtraxx,
QSI and practically all others) These large microfarad caps are necessary
to isolate minor disturbances in track pick-up from interfering with
operation of the sound control computer in the loco decoder. The problem
is that when several sound equipped locos are present on the track,
the booster and electronic circuit breakers have difficulty starting
up and/or restoring track power after a short circuit because the large
inrush of current necessary to charge up all the large capacitors simultaneously
causes them to re-trip.
Solution: Place a current limiting light bulb in series
with each lead from the booster to track. (the 1156 or modern equivalent
automotive
tail-light bulb again) Provide a DPST normally closed switch in parallel
with bulbs so that under normal conditions track current flows through
the switch, not the bulb. Use a momentary push-button or spring loaded
toggle switch with normally closed contacts. (rated for booster/track
current amps)
Now when/if the booster cannot recover, momentarily open the switch
so that:
1) Booster output current is limited by the light bulb, allowing
the booster to recover.
2) If the track short still exists, the light bulbs will illuminate
to indicate that there is a hard track short that needs to be fixed.
3) If the track short has been removed, the booster will recover
but track current will be limited by the light bulbs, allowing....
4) The large energy storage caps in each loco decoder will charge
up under limited current conditions. The booster will not re-trip
on over
current. Then....
5) When the booster is seen to recover (usually after a few seconds
after the short is removed, plus a fraction of a second to charge
up all the capacitors) release the switch to re-close around the
light
bulbs. This will fully restore track voltage and current capacity.
Design Improvement Twists:
1) If one uses electronic circuit breakers for track current distribution
(Digitraxx, NCE, On-Guard, etc.) wire the light bulbs in parallel
across the CB. That is, each bulb has one wire to the input side
of the CB
and the other wire to the corresponding track output connection of
the same polarity. The electronic CB takes the place of the manual
switch in the above scenario, but recovery is now automatic (if the
electronic CB is set to do so). [Some multi-channel distributions
CBs designed for this purpose have one power lead as a through-wire
and
will need only one bulb per channel.]
2) One cannot do the above if the electronic CB is also meant to
auto-reverse.
3) A lower cost method would be to substitute a conventional DPST
or DPDT, 12Vdc operated relay to do the above auto-recovery switching.
Use normally open contacts of the relay (rated for booster current)
to bypass the light bulbs. Power the 12Vdc coil from the DC output
of a small full wave bridge rectifier (maybe with a slow-to-operate
R-C delay). Wire the AC input side of the rectifier bridge to the
track
power side of the lamps. Now when track power is shorted or the booster
trips or is shut off, the relay will drop out, placing the bulbs
in the track circuit. When the booster is first powered up or resets,
track current will be limited by the bulbs. When all the caps are
re-charged,
track voltage will build up to near normal levels allowing the relay
to pick up and jumper out the light bulbs.
Any 12VDC relay may be used. Use a relay rated for 10A
to ensure long life.
| |
Description |
Radio Shack P/N |
| Z1 |
Bridge rectifier, 50V, 1A or higher |
276-1152 |
| Bulbs |
1156 Automotive tail light bulb |
. |
| Relay |
12VDC, 10A |
275-218 relay
275-220 socket |
See the section on parts for
a relay that doesn't require a socket and has built-in mounting tabs,
Digikey P/N PB159-ND.
SUGGESTION #4-10: Divide
and Conquer a Short in Your Booster Bus
Track Wiring #5-21 has a good discussion
on localizing a short. If you used phone connectors to make your
booster bus, you can just disconnect them rather than cut the wires.
If you ran a separate ground between
your boosters, just try to localize the problem with leaving this ground
connected to all boosters first.
SUGGESTION: How to Test Your
Booster
If you tried shorting your
track to verify that your booster will shut down and it did not, try
the test again. This time, directly short out your booster. If your
booster does not shut down, you may not have it set up right or it
may be defective. But more likely, you are using a power source that
cannot adequately supply all the power your booster needs to trigger
its overload detection circuitry. See the section above, Be
Sure to Use a Transformer for Your Booster That Puts Out AT LEAST as
Much
Current
as the Booster
Can.
SUGGESTION
#4-11: Buy a Spare Command Station/Booster
It is always a great idea to have spare equipment on hand.
You only have one command station. If it goes down, you whole layout
is down. Also, if you have two, when it is time to upgrade them, you
can send one back at a time.
Yes, these cost money. So this is only a suggestion.
However, if you have a system like Digitrax Chief, the cost of doing
this is
only about $50. The Chief is both a command station and a booster.
Furthermore, the Chief can be placed in a booster only mode. The cost
difference
between buying a Chief set versus a booster, a throttle, and a decoder
is only about $50. Keep one of the Chiefs in booster only mode and
use
it as you would a booster. Should one of the Chiefs fail, you can use
the second one after you restore it to Command Station/Booster mode.
Note: You can only have one command station per
system! If you are using a spare command station as a booster,
you must set that command station to booster only mode. See Suggestion
#4-12 below on how to do this.
SUGGESTION #4-12: Use Spare Command Station as
a Booster
Here is how to turn a spare Chief (DCS 100) into a booster.
1. Set Op switch 2 to C.
2. Set Op switch 5 to T.
You will then need to set it to auto reversing mode or
non-reversing mode.
Auto reverse mode: Set Op switch 3 to C.
Non-reversing
mode: Set Op swtich 3 to T.
See Chief manual on how to set Op switches on page 117.
Mysterious Operation
My radio throttles seemed to become unresponsive. When
I plugged into Loconet, the throttle would seem to freeze. What was
my problem? It turned out that the command station (Digitrax Chief)
was overheating. The manual says that the Chief command station will
keep working even if the booster section overheats. This turns out not
to be true. I put a muffin fan on it and the problem went away!
I had a booster that would trip but it didn't always
reset. So I put a small muffin fan on it. So far, so good.
Does this means you need to put a fan on your command
station or boosters? Not necessarily. But if you have erratic operation,
especially operation that seems to get worse as the day goes on, it
might be something to consider. Make sure you have fresh batteries
in your throttles. Reset the variables, slots, and such in your command
station. If all this fails to get your erratic operation to go away,
try a fan.
Definitely make sure your booster and command station
can get some air. If you have encased them, you may be causing heat
failure.
