I did not follow every single one of these good
tips, but I sure did appreciate the diagrams with
the colored lines and power blocks. It's like he
knows what's it like to be me, to have some fear
of misinterpreting schematic diagrams, and even
basic electrical words like "ground". But I do my
best.
This text below by Gregory Braun, RIP
Track Power
Modern AFX and Tyco slot car motors require a
power supply producing 18 to 20 volts of direct
current (VDC), while older Model Motoring cars
require 20 to 24 VDC. The wall-outlet power pack
supplied with most boxed racing sets is not
sufficient for use on large table-mounted racing
layouts.
DC power supplies normally have two
specifications, the output voltage and the output
current. Modern HO slot car motors require at
least 18 VDC, and 1 ampere or more of current for
proper operation. Most of the DC power supplies
currently being manufactured provide only 12
to 13.8 VDC. These WILL NOT work for HO slot car
tracks. They will however work properly for
larger 1:32 and 1:24 scale slot car tracks.
A good quality DC power supply is essential to
safe, trouble-free racing and prolonged motor
life. Investing in a good power supply will
quickly pay for itself in motor savings alone.
A good rule of thumb to use when determining the
size of the power supply required is to multiply
the number of lanes by 1 ampere. Especially long
layouts or very hot motor armatures may require
more power, but 1 ampere per lane should be
sufficient for all but the most demanding racing
situations.
A 5 ampere DC power supply would be a good choice
for a long 4-lane racing layout. This should
provide sufficient power with an adequate reserve.
Power needs to be applied evenly around the entire
race track. Slot car tracks with lane lengths
greater than about 20-25 feet will need to have
power applied at several locations. The rail
connections at the joints in plastic sectional
track are the single largest factor contributing
to voltage drops as the cars move farther and
farther away from the power terminal track.
It is often said that power should be applied
every 15 or 20 feet for an even power
distribution. This is true, but an even better way
of determining power terminal track spacing is to
count track joints. It is the joints that rob your
track of power not just the length. Applying power
every 12 to 15 track joints will assure that your
track is properly powered.
It is important to determine where power will be
applied before you build your track and mount it
permanently to a table. Racers who skimp on
adequate track power distribution will be
disappointed when they have completed their track
and find that cars slow dramatically on those
sections of the race track farthest from the power
taps.
Replacing the power supply with a unit producing
higher amperage has very little effect on power
distribution. Inadequate power distribution
produces voltage drops around the circuit. All of
the amps in the world can't overcome this drop in
voltage though.
Powering each lane with 1 or 2 amperes is
sufficient if power is distributed evenly. It's
far more important to apply track power evenly
around the racing circuit than it is to have a
high-output power supply feeding a single set of
power terminal tracks. Regardless of the power
supply output, cars will slow down dramatically as
they travel farther away from the power source.
Generally speaking, a 4-lane race track mounted on
a 4x8 foot table would require 2 or 3 power taps,
while a 4x12 foot table would probably require at
least 4 or 5 taps. Even larger and longer race
tracks may need as many as 10 power taps. Count
the joints for a single lane and then divide by 12
or 15 to get a better idea as to how many power
taps your particular track design requires.
Commercial Power Supplies
Astron is a good source of high quality DC power
supplies for HO slot car racing layouts. The
Astron catalog lists a nice 0-30 Volt Variable DC
Power Supply producing 10 amperes of power.
Astron power supplies are fully regulated. A
regulated power supply eliminates power surges
associated with other multi-lane power supplies.
Three different power supplies are available:
The Astron Series of DC power supplies have 0-30
VDC variable voltage outputs as well as adjustable
current output ranging from 1.5 amperes to the
full load rating.
I'm selling the Astron Series of DC power supplies
for both HO and 1:32 scale slot car racing on my
Order Form page.
A variable voltage DC power supply will also allow
you to reduce the voltage when young or
inexperienced racers drive your cars. Reducing the
voltage to 9-12 VDC will make it much easier for
very young children to race without having the
cars constantly flying off the track. As their car
handling skills improve you can increase the
voltage gradually until they are using the
full 18-20 VDC that modern HO tracks normally use.
Power Requirements
The table below shows the maximum peak current
(amps) drawn by various types of HO slot car
motors.
HO-Slot-Car-Current-Requirements.gif
Track Wiring
Neat track wiring is important. Spend the extra
time to properly wire your slot car racing layout.
Solder all connections whenever possible, or use
crimp-on connectors if you do not want to solder.
Use 14 of 16 gauge stranded wire for all power,
controller and track connections. The increased
wire gauge will guarantee safe racing.
The diagram below illustrates the track wiring
required for a single lane. Expand this for the
number of lanes your racing layout has.
slot-car-wiring.gif
A 2 ampere fuse should be sufficient to protect
your car and controller. If you run hotter motor
armatures you may need to increase the fuse rating
to 3-5 amperes. Each lane should be individually
fused. Do not use a single fuse for all lanes.
If your controllers do not include a brake circuit
eliminate the red wire running from the controller
connection to the track power grid in the diagram
above. If you have both types of controllers you
can retain the brake wiring circuit and only use
it for those controllers that have braking built
in.
See the Construction section of this web site for
step-by-step pictures of a 4-lane raceway being
built and wired using the wiring schematics below.
The diagram below illustrates typical 4-lane
wiring using standard dual-row barrier terminal
blocks for all power, controller and track
connections. This wiring method uses solderless
crimp-on spade lugs for all barrier terminal
connections.
Longer race tracks will require power to be
applied at several locations around the racing
circuit. The barrier terminal blocks on the right
side of the diagram below illustrate a wiring
scheme for a track with power applied at two
individual points on the race track. You can add
extra terminal blocks if you plan to apply power
in more than two locations. The actual length of
the wires between the track terminal blocks will
be longer than those illustrated below.
slot-car-4-lane-wiring.gif
The 4-lane track wiring diagram shown above can be
used with a single power supply or individual
power supplies connected to each lane. If a single
power supply is to be used bridge the four
positive power lines (white wires) together with a
four position barrier terminal jumper. Use a
second four position barrier terminal jumper to
bridge the four negative power lines (red wires)
together as well.
The 18-14 Gauge wire tap-ins specified above are
used to connect controller brake circuits to the
negative power lines.
The 4-lane track wiring diagram shown below is a
simple variation on the previous diagram. It
employs a 4 position barrier terminal at each
driver station to tie the brake circuits together
instead of wire tap-ins as used above.
The 3 Position Barrier Terminal - RSU 11673209
used in the diagram above is a special order item,
whereas the 4 Position Barrier Terminal -
RS 274-658 used in the diagram below is available
at all Radio Shack retail outlets.
slot-car-4-lane-wiring-2.gif
The 4-lane track wiring diagram shown above can
also be used with a single power supply or
individual power supplies connected to each
lane. If a single power supply is to be used
bridge the four positive power lines (white wires)
together with a four position barrier terminal
jumper. Use a second four position barrier
terminal jumper to bridge the four negative power
lines (red wires) together as well.
Parts Required
3 - 8 Position Barrier Terminals - RS 274-670
4 - 4 Position Barrier Terminals - RS 274-658
4 - #8 Spade Terminal Packs - RS 64-3128
1 - 8 Position Jumper - RS 274-650
1 - 8 Position Jumper (Optional) - RS 274-650
The 8-position jumper specified above can easily
be cut into the two 4-position sections required
for race tracks using a single power
supply. Simply remove the two jumper strips if you
change to individual power supplies for each lane
at a later date.
The wiring diagrams illustrated above assumes that
power fuses are installed at each of the four
driver's stations.
Driver's Stations
Simple and very attractive driver's stations can
easily be made to allow racers to connect their
hand controls. Purchase a 2x4 inch plastic project
box from Radio Shack (Part No. 270-1802) for each
lane. These boxes come with both a plastic and
aluminum cover. Use the plastic cover and paint it
to match the color of the lane it will control.
Only the plastic cover is required, so save the
aluminum cover and the lower section of the box
itself for other projects.
Hand controls normally have black and white power
wires and a red brake connection. You can purchase
corresponding black, white and red banana jacks
and plugs from Mouser Electronics. Do not use the
banana jacks and plugs sold at Radio Shack though
as these are very poorly made and will not
maintain a good electrical connection. Radio Shack
does not offer a white banana plug or jack. It is
very important that you maintain the red, white
and black color scheme so as not to confuse
racers.
The diagram below illustrates a single lane's
driver station. The banana jacks are mounted
in 5/16 inch holes drilled on 1 inch centers.
slot-car-drivers-station.gif
If you have hand controls that will always be used
with your race track install banana plugs on each
of the three controller leads, maintaining the
proper color coding.
If you would like to use alligator clips to
connect your hand controls then remove the hoods
from the banana plugs and just insert them in the
jacks. These bare plugs will form posts that can
be used to attach the alligator clips to.
If you mount banana plugs on some controllers and
leave the alligator clips on other hand controls
then purchase some extra banana plugs to use as
posts when you want to use your hand controls with
alligator clips.
slot-car-drivers-station-fused.gif
If you want to add a power fuse at each driver's
station purchase a 2x6 inch project case instead
(Cat No. 270-1804). The additional length will
allow enough room for its mounting. The list below
contains the Mouser Electronics part numbers for
the plugs and jacks you'll need to purchase:
White Banana Plug Red Banana Plug Black Banana
Plug
530-108-0901 White Banana Jack
530-108-0902 Red Banana Jack
530-108-0903 Black Banana Jack
530-108-0301 White Banana Jack
530-108-0302 Red Banana Jack
530-108-0303 Black Banana Jack
For a typical 4-lane layout you will need to
purchase four (4) of each of the items listed
above. The Mouser Electronics web site has all of
these items available on-line. You can also place
an order by calling their toll-free number
at 1.800.346.6873
See the Construction section of this web site for
pictures of fused 3-wire driver's stations being
installed in a 4-lane raceway.
If you would prefer to purchase ready-made
driver's stations as described above see the For
Sale section of this web site.
Custom Power Supply
If you feel comfortable building your own
electronics projects you can easily make the DC
power supply illustrated below for under $15
dollars per lane.
slot-car-1-lane-schematic.gif
If you would like to provide individual power
supplies for each lane of your race track this
simple design will produce 3.5 amperes per
lane. This power supply would be ideal for large
layouts or HO Slot Cars using hot armatures.
This power supply design uses only three (3)
components available from Radio Shack's web site
or your local Electronics Parts Store.
A 4-lane power supply using four (4) of each of
the components listed above will cost you less
than $60.00, yet will provide 3.5 amperes per
lane, for a total power output of nearly 15
amperes.
This power supply design uses a classic full wave
diode bridge circuit (D1) to rectify the
transformer's secondary AC output (T1). The
capacitor (C1) smoothes DC ripple.
The instructions and schematic for building your
own custom power supply have intentionally been
left rather vague. If you're comfortable working
with the 120 VAC primary side of the transformer,
or know someone who is, perhaps a HAM radio
operator, then this would be a simple one-evening
project. Due to the high voltage primary wiring on
the transformer this project should only be
undertaken by someone who understands what they're
doing. This is NOT a good first project for the
electronics novice!
Power Terminal Tracks
Power terminal tracks from Tyco and Tomy are
expensive and will not allow you to use individual
power supplies for each lane. Longer layouts need
to have power applied at several locations on the
layout. Using manufactured power terminal tracks
can become quite costly.
This section describes a method of making your own
power terminal tracks from standard straight track
sections.
Making your own power terminal tracks is quite
easy. All you will need is a soldering iron,
soldering flux for electronics, and some
rosin-core electrical solder. You will also need
some short lengths of 16-18 gauge connection wire.
Note: The information provided here can also be
used to attach wires to dead track sections used
for electronic lap counters.
Start by placing a straight section of slot car
track upside down on a towel dampened with cold
tap water. The damp towel will prevent heat from
the soldering iron being transferred to the
plastic track.
The metal power rails running along each side of
the guide pin slot are secured to the plastic
track itself at 3 inch intervals. Locate a pair of
these mounting points midway down the length of
the straight track section and place a small dab
of soldering flux on the exposed metal rail
mounting points.
Cut two 12 inch lengths of hook-up wire and strip
away 1/4" of the insulation from one end of each
wire. With a hot soldering iron heat the exposed
wire and apply a small amount of solder to the
heated wire. This tinning process will make later
attachment to the metal power rails much easier.
Place one of the tinned hook-up wires at the point
on the metal power rail where you had previously
applied soldering flux and hold your soldering
iron on the joint. Apply a small amount of
additional solder once the flux begins to boil,
and then carefully removed the soldering iron. Let
the solder cool naturally, do not blow on the
heated solder though, as this may fracture the
soldered joint you just made.
Repeat the process described above for the
remaining three metal power rails on a two-lane
section of plastic slot car track.
Longer slot car tracks will require power terminal
tracks placed at intervals around the circuit. The
running length of track between power terminals is
not nearly as important as the number of track
joints separating the power terminals. The track
joints themselves are the largest source of
electrical resistance. A good rule of thumb is to
use a power terminal track for every 12-15 track
sections.
See the Construction section of this web site for
pictures of power terminal tracks being installed
in a 4-lane raceway.
If your slot car track employs a dead track
section for an electronic lap counter use two
power terminal track sections, one before and one
after the dead section.
If you would prefer to purchase power terminal
tracks made using the process described above see
the Order Form section of this web site.
Tomy AFX 2-Lane Dual Power
2-Lane Tomy AFX track owners can easily configure
their tracks to use individually powered lanes by
simply adding a second Tomy AFX power terminal
track and power pack.
The diagram below illustrates how to wire any Tomy
AFX 2-lane race track to use individually powered
lanes. This method will double the power available
to each car, and eliminate the power surge
problems associated with a single power supply.
slot-car-2-lane-afx-wiring.gif
Simply insert a second Tomy AFX power terminal
track into the layout with the connection block
exiting from the same side of the track as the
first one. Then connect one power pack and one
hand control to each power terminal track. Each
hand control needs to be connected to the
corresponding lane it will regulate.
The diagram above shows two power terminal tracks
placed next to one another for simplicity, but
they can actually be placed anywhere around the
raceway to allow the two drivers stations to be
located at different points around a larger table.
Tomy AFX 4-Lane Quad Power
4-Lane Tomy AFX track owners can easily configure
their tracks to use individually powered lanes by
simply adding two additional Tomy AFX power
terminal tracks and power packs as illustrated
below.
4-lane-afx-wiring.gif
Track Power Testing
Nothing is more frustrating than racing on a slot
car track with corroded or loose power rail
connections. Here is a simple and fool-proof
method of locating bad track joints.
Start by first removing the last track section
before the power terminal track and then slowly
drive a car around the track until it
stops. Whenever the car stops inspect and clean
the power rail joints at the track section just
before the loss of power occurred. Repeat this
process for all lanes until the car travels around
the entire circuit without slowing or stopping.
slot-car-power-test.gif
Finish up by replacing the last section of track
and now you'll have a race track without any power
losses.
