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SwitchMaster premium slow-action switch machines employ fine-quality powerful gearhead motors from Hankscraft.

SwitchMaster Installation Options

Wiring schematics and instructions sheets are provided with each SwitchMaster switch machine and accessory. They and additional information are posted here for your convienance.

These and ALL materials posted and printed ARE COPYRIGHT Builders In Scale / SwitchMaster © 2003-2016. They may be copied for NON-COMMERCIAL USE only.


We are always in the process of developing this section with more information, ideas, photos and examples-

SwitchMaster switch machine isometric photo of installation.



SwitchMaster 1200 ohm resistor.
A 1200 ohm resistor

After reading the instructions consider the following...

While a 1200 ohm resistor is supplied with your SwitchMaster it may or may not be the right one for you.

In most cases we've found 1200 ohms is about right for the typical power pack auxiliary supply. While these are often labeled as 12 Vdc sometimes the power coming out of them is 18, 20 or more volts! 1.2k is on the safe side. If your motor runs too fast or slow, or not at all, changing the value of the resistor is indicated. There are so many variations from old to new, cheap, or expensive power supplies- as well as other considerations such as your wiring (small gauge wires going to a machine far far away) and components (old or "cheap" toggles", adding lamps or LEDs all add to the equation), the work the motor must do to throw the points, the type and size of the turnout, and so on. So a little tweaking might be necessary.

Beside replacing the power supply with a higher or lower output consider changing the value of the resistors. If your turnouts are for the smaller scales you'll likely want to turn the power down more than the larger scales that might need more oomph. Consider leverage here too. Is it a short strong throw or a longer, less powerful stroke. I told you pay attention in high school shop class, math, physics...

Or maybe you have a switch in a difficult location that requires a bell crank or other mechanical linkage that will require more power than your other turnouts. This might mean that you'll want to change the resistor for just this one particular motor.

SwitchMaster switch machine resistors.

Our #1121 Resistor Test Pack
includes 10 different values of resistors.

We'll make this easy for you by offering a set of 10 different resistors, our Part #1121. Use them to determine which value is right for you. In general, once you find the right value for your set-up all the others should follow suit. We can do this by trail and error. If the motor is too fast that means your power supply is putting out lots of voltage. Try one of the higher values (1.5K or 2.0K). If the motor is running slowly or not easily starting let's try one of the middle values (1.0K, 680, 390). If your power supply is weak then try one of the lower values (330, 270, 220). For instance, with one power supply we tried the 1200 ohm resistor was just too much. The motor didn't move at all. By trying different resistors we figured out 680 ohm resistor was right for the circuit. On another power supply 1200 ohms was the right value on the same circuit. If none of these ten resistors works then it's time to try another power supply.
We should probably post the color code for all these but it is included in the test pack.


It does not matter which motor lead (+ or -) the resistor is connected to, just so long as it is conneted between the power supply and motor so it can limit the current.


We don't sell power supplies because they are readily available at a better price than we could offer. Besides, most model railroaders have one or two extras lying around or could snag one at the next swap meet for next to nothing. Old computer power supplies offer 12 Vdc, too. Who doesn't have an extra one of those in the closet? A wall wart will also do the trick. These are really pretty basic machines.


It is possible to use alternating current (AC) to operate our switch machines. We know, we warned you not to do that. Well, yes, we did, but we rectified the ac using diodes (1N4001) (same as our part #1104) on SPDT toggles to convert the AC power into direct positive or negative current (DC). Pretty tricky, hun? Not really, just basic electronics. In our case the power supply is nothing more than an 8-volt door bell transformer. For these circuits the 1200 ohm resistors was way too much but we found that 270 ohms was just right.


Okay, if you don't have a package of assorted resistors in hand there are some tricks you can try. If you take two 1200 ohm resistors and tie them together in parallel (side-by-side) the result will be 600 ohms. Tie three together and you get 400 ohms. Tie four and it's 300. The current has four ways to travel. So it's one forth of 1200 ohms. Take two 1200 ohm resistors and tie them together in series (nose-to-tail) and you get 2400 ohms. It's twice as hard to pass through. Thus, if you don't have the particular value you need often you can build something that has the required value. They did teach you this stuff in junior high shop class didn't they?

SwitchMaster 470 ohm resistor.
A 470 ohm resistor, as supplied with our LEDs

A potentiometer is also available. Our part #1132. It's an adjustable resistor. By turning the thumbwheel we can adjust the resistance from 0-1000 ohms. We'll suggest you do what we have just talked about, tying the potentiometer in parallel with the supplied 470 ohm resistor (or as needed) and fine tune the circuit with the adjustable potentiometer. We've found this very useful for those one or two motors that might have a little more (or less) work to do than the others.

And one last trick. Say you have a sticky switch or two that always seem to need an extra nudge to get going. Rather than reaching under the table each time use our part #1140 "Kick Switch" to get it going. Here in series we are doubling up on the 1200 ohm resistor (you may have to experiment to find the right value) thus supplying the motor with a lower "holding" voltage. Press the momentary (on) Kick Switch bridging over one resistor so a higher "moving" voltage through just one resistor is applied to the motor when you throw the operating toggle. Problem solved.
Yes, it is an extra step each time you throw a turnout but think of the switchman or conductor jumping on the ground to do the same thing. Employing these will certainly add to the lifespan of your switch machines especially if you are running them hot.

Okay, so that's all we know. Most of it anyway. Hope it was of help.
If you get stumped, send us an email.
Meanwhile, we've got structure kits and detail parts to do! Bye.


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