UTP - Universal Throttle Panel Hints and
by Don Fiehmann, Rev Feb 2005
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Universal Cab Bus Throttle Assembly
for NCE, Digitrax and Lenz and DCC systems
These notes are one of the evolving
tip sheet on DCC subjects. The source of these tips comes from customer
questions, personal experience, the internet and technical information.
This note is on the installation and operation of the UTP (Universal
Throttle Panel). The UTP will work with NCE, Digitrax, and Lenz
It is hard to believe that it has only been a few years ago that
model railroaders were set free of the stationary throttle. Before
walk-around train operation was like we were overlooking the layout
from an Ivory Tower. Walk-around throttles and cabs allowed us to
get close to operation of our trains. Radio and IR linked wireless
throttles have even improved the ability follow the action.
The problem is wireless links are not
100% reliable. Batteries go low, transmission paths can be blocked
and other things can happen. Most manufacturers of DCC systems recommend
that plugin panels be placed around the layout to allow cabs and
throttles to be plugged into the net when needed. Most system operate
more reliably when connected with a tethered connection than with
wireless connection. Programing is more reliable with a wired connection.
The popular way to connect DCC system
throttles or cabs is using telephone types of connectors and cords.
Another reason for the popularity of the phone type connectors is
the low cost and the ease of replacing a faulty or broken connector.
Even though DCC systems use different protocols (LocoNet, Cab Bus
and so on) connections between the command station and cabs or throttles
can use the same type of connectors and cables. This is why the
UTP (Universal Throttle Panel) can be used with a number of different
The UTP is designed to be a low cost unit to allow easy walk-around
connections to be distributed in several convenient locations on
a layout. The UTP comprises of a small printed circuit board with
four RJ-12 connectors wired in parallel. Two connectors on the back
are used to daisy chain the cable from the command station
to more UTPs. The two connections on the front of the panel are
used to connect to throttles and cabs. A metal panel is supplied
to for mounting the UTP on edge of the layout of other convenient
The Universal Throttle Panel is can
be used with the (A) Cab Bus on NCE, (B) LocoNet on D igitrax and
(C) Xpress bus on Lenz systems. The UTP will not work with the MRC
Advance Prodigy system because it uses 8 wire cables.
The optional power connector allows additional power for the cab
bus/LocoNet cable. This power is needed on DCC systems when the
number of cabs or throttle exceed the limited power available from
the command station. There can also be a problem with voltage drop
on long cables. The telephone type of cable is used between UTPs
is a light wire (#26 or #28 gauge wire). The wire size is OK for
the signals but may cause a problem for power on long runs of 30
feet or more. Number 28 wire has a resistance of just under 2 ohms
in 30 feet. For the current to flow both ways thats 4 ohms.
It would not take too many cabs plugged in to develop a high voltage
drop. This is why added power is needed on long runs or systems
with many cabs operating at one time.
Problems may show up as intermittent
cab trouble when using many cabs or cabs at the end of long cable
runs. Power can be added with a TTE-XNCE wall plug-in type power
supply. This 12 V DC 1 amp unit has the correct plug for the back
of the UTP.
There are a number of different wiring options for the optional
LED. The LED can be installed as a status indication and /or provide
an easy way to locate the UTP in a darken layout room.. The LED
can be used to indicate power on the cab bus/Loconet cable. If connected
to the rails near the UTP it will indicate power on the rails. A
third option is to separately power the LED.
Any color LED will work with cab bus power. If you are using track
power use a Bi-color red/green LED. A 3 mm LED will fit thru the
hole in the front panel.
The LED should have the leads bent so
the LED will fit thru the hole in the front panel and the leads
go thru the two hole in the circuit board. The shorter lead on the
LED goes thru the square hole next to the K on the board. (K for
Install a 1K (1000) ohm 1/4 or 1/2 watt
resistor in the two holes marked R1 and 1K on the component side,
solder on the side marked R1.
Powering LED from Cab Bus
Two jumpers are needed to power the LED from the cab bus or XpressNet.
Run one jumper from the LED + to the +connection above. Then run
a second jumper from the connection to the LED connection.
W ill not work with LocoNet (Digitrax)
Powering LED from the Track Power
Two wires are run from track power to the LED+ and LED connections.
(This application requires a Bi-color LED.) These two holes will
take a #4 screw if you dont want to solder the wires. OK with
Powering LED from an External Power
A voltage source from 5 to 15 volts dc can be used to power the
LED. Connect the positive wire to LED+ and the negative wire to
LED . OK with LocoNet (Digitrax)
1. Face Plate Grounding: Add a jumper
to Y Y on the circuit board. This connects the front panel to the
2. External Power Supply: Cut the trace
at Z Z on the circuit board. Install a 22 ohm 2 watt resistor at
holes marked A A. Connect external power supply to holes marked
(+) and ( ). Install a wire to the hole marked COM from panel
3.Digitrax Battery Saver with command
station in sleep mode: Add five diodes to D1,D2,D3,D4 and D5 as
shown on the circuit board. Cut the trace at location X X on the
circuit board. Install a wire to the hole marked COM from panel
Cables and Cabling
There are two options on cables. They
are available made up in different lengths. Or you can make your
own custom length cables. Cables are easy to make. Cables can be
used for either the UTP to UTP daisy chain connections or for the
UTP to handheld cab. Most of the handheld cabs and throttle use
4 wire cables and connectors. There are two sizes of connectors.
The 4 and 6 wire connector or the smaller 4 wire that is used for
By making them yourself they can be
cut to custom lengths. With a good crimper repairs to cable ends
are a snap. I started with a cheap plastic crimper and found that
it was good for making defective cables! A good cable starts with
a good metal crimper! (The cost of a good tool is soon forgotten,
but you will curse a cheap tool every time it is used!) These connector
are the IP or insolation piercing type of connection and require
a lot of pressure for the contacts to cut through the insulation.
Most crimpers have positions to 1.cut, 2.remove insulation and 3.crimp.
The crimper should be able to handle both 6 wire and 4 wire connectors.
Here is a chart that shows the different wire usage
with different systems.
||No Connection (Reserved)
||+ 12 volts
||+ 12 Volts
||No Connections (Reserved)
To install a connector start with a clean cut. Then skin back the
insulation to expose the wires. Put a connector in the crimper and
place the cable in the hole in the connector. The white wire goes
to pin 1. Then squeeze all the way down. Most DCC systems require
that the cable have pin1 to pin1 connections. Cords make for telephone
service can be different. All DCC systems require the 1 to 1 pin
connection (See drawing) except Digitrax. The Digitrax system can
use either the pin 1 to 1, or pin 1 to 6 configuration. If you make
all cables pin 1 to 1 you cant go wrong for any system!
Crimpers perform three functions.
The UTPs should be installed in locations near the action. Yards
and industrial areas are good candidates. If you use wireless cabs,
locations where you have problems communicating would another good
spot. The distance between UTP panels should be less than half the
length of your cab cables.
The cables should be twisted about 1 or 2 times per foot between
UTPs. These cables should spaced at least 6 inches to a foot away
from track power wires. If you have to cross over the track power
wires do so at a right angle. These suggestions will minimize the
crosstalk between the cab bus and track power.
Do not use staples to hold the cable
in place as they may pierce the cable and short it.
Connect the UTPs together with about
1 to 2 twists per foot.
|Cab Bus Accessories
||The following parts and supplies available
from Tonys Train Exchange
||UTP/TTE Universal Throttle Panel with four RJ-12
connectors - link
|| Plug-in 12 V DC power supply for UTP panels
|M PP (??)
|| Assembled 6 wire Cables 5ft= MPP5, 10ft=MPP10,
15ft=MPP15, 20ft=MPP20. Longer cables available - link
|| Six conductor flat Phone Cable (for making
your own cable) - link
|| Coiled 6 conductor. (Minimum 10 foot order)
|| Female (socket) to Female (socket) connector
for 6 wires - link
|| Two way Splitter, 1 Male (Plug) to 2 Female
(socket) connections - link
|| Crimp on RJ-12 six conductor plugs - link
|| Crimp Tool for 4 or 6 conductor plugs. - link
welcome comments or suggestions from readers; please write