COMPONENTS
14 GARDEN RAILWAYS FALL 2019
C THROTTLE
When searching Amazon.com for throt-
tles, you’ll find many choices in a variety
of styles. You’ll want to look for two
things: voltage and current. (See my arti-
cle in the Summer 2019 issue to learn
more.) If your power supply is putting out
24 volts and 5 amps, your throttle needs
to be able to handle that. Some of these
controllers are small enough that you
could fit them in a box small enough to
fit in your hand, which would allow you
to build a walk-around style controller.
A built-in direction switch is also a
nice feature, saving you the trouble of
wiring that yourself.
Note that the output of the majority
of these controllers is pulse-width modu-
lation (PWM). If you’re running locomo-
tives equipped with DCC or other com-
mand control electronics, they may not
run well, so you would want to add filter-
ing to the output of these throttles. There
are simple filtering circuits available
online if you’re electronically inclined.Wiring everything together
Wiring the whole assembly is simple. See “Anatomy of a DIY Power Supply” diagram at
right. Three wires (live, negative, and ground) come from the power socket assembly
(A) to the power supply (B). Two wires (plus and minus 24v) go from the power supply
(B) to the throttle box (C). Two wires from the throttle (variable track power, C) go out
the back of the box to the track. I attached the throttle output wires to two screws on
the box, but you could also use a two-wire plug or another connector.
The unit may not look f lashy, but it gets the job done. With the components I
ordered, I paid about $35 total for this unit. Including some extras (filters, cooling fans,
fixed DC voltage outputs, voltage and ammeters, etc.) may add $20-$30 to the price,
but you’ve still freed up extra funds for more track. Because what good is a throttle if
there’s no track to power?B POWER SUPPLY
You’ll want something with enough guts
to run a fairly large locomotive, so I’d
look at nothing less than 5 amps
capacity. If you’re looking to run
double-or triple-headed locomo-
tives, you may want to buy a 10-amp
supply instead. You’ll also want a
supply that will provide ample
voltage, so look for a unit between
18 and 24 volts. Do not exceed 24 volts,
as the electronics in our trains are usually
designed for that maximum.D CONTAINER
The last thing you’ll need is an
enclosure for the components. You
want something big enough to hold
everything, but not too large so it
becomes unwieldy. I’ve seen other
hobbyists use plastic project boxes
from electronics supply stores, or
even surplus ammo boxes. I found a
basic plastic toolbox at the dollar
store. It cuts and drills easily, and
plastic does not conduct electricity.
Don’t forget to include a means
of ventilation in your container.
The most simple form is passive ven-
tilation, done by drilling some holes
in the sides or back of the container
so that air can freely circulate
through the box. You can install a
cooling fan if you’d like to draw air
through (see Materials list). You can
tap that from the fixed DC output
of the power supply. Just make sure
the fan is rated for the supply’s
output voltage.A POWER SOCKET
This critical piece of equipment
brings the power from the outlet in
your wall into the socket, which will
deliver constant DC voltage out to
the power supply. When you search
for power sockets, you’ll usually find
two kinds.
The first kind has screw termi-
nals to which you connect all the
necessary wires to route power to
and from the power supply. These
typically cost between $7 - $30,
depending on voltage and current
capacity. This type requires users to
wire the cord, which plugs into an
electrical wall outlet, and a power
switch into the system. If you’re
uncomfortable about wiring any-
thing with household current, you
may want to avoid these sockets.
You can also find pre-assembled
power sockets with just two wires,
for the DC voltage) coming out of
them. They may cost bit more ($15 -
$50), but they simplify the wiring
(see photo above). The only catch is
that there’s usually no on/off switch.
(They’re designed to be external
power supplies for printers, comput-
ers, and other electronic devices
which would have power switches
built into them.) But no worries, you
can plug it into a power strip and use
that as a switch instead.
GARDEN RAILWAY BASICS
LEARN MORE
The author’s book, Garden Railway
Basics (#12468), includes a chapter on
track power and selecting power
supplies/control systems. Order at
KalmbachHobbyStore.com