Control for Twin Coil 3-Wire Machines

Many switch machines use a pair of electromagnetic coils powered by a sudden snap of DC current. The current required is very large but only for a moment. Traditionally the left and right wires are connected to each coil’s activation power with a common center return.


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We created our Snap Action Base to let you power Twin Coil machines as simply as possible. There are just three screw type output terminals that connect to each motor. Each Snap Action Base can operate 4 turnouts.

Our Snap Action Base was stores up a charge in an on-board capacitor, kind of like an instant delivery storage battery. When an attached Touch Toggle is touched it triggers a flood of current into the connected switch machine coil. It becomes a powerful electromagnet for a moment, pulling an iron core to the left or right. Controlled by the Snap Action Base, this current is only turned on for a fraction of a second, so no matter how large or small the switch machine no heat buildup or current overloading can damage your machine. The Base then recharges for the next operation. That way that every coil gets a full powered snap every time. If two or more Toggles are touched at the same moment, they will each operate in turn, with a brief wait for the Base to recharge.

With this careful power management in place you’ll never have to wait for a power unit to recharge, like in the old days. Even better you can operate 20 or more turnouts on a single small power supply.

Since each coil needs it’s own snap of power to ensure a proper throw, we recommend each machine connect to it’s own output terminals. When you are operating two or more turnouts together in a crossover, we suggest using an Input Splitter to let one Toggle connect to 2 or more inputs.

Get started with a Snap Action Package which includes a Base and all the Touch Toggle controls you need for that size Base.

Dont forget a 12v power supply for the complete system. Like all of our 12v Bases, the Snap Action Base has power-sharing pins on either side, so one base can plug into another to share a single supply. All the details on providing power is available here: About Power For Touch Toggles 

Common Twin Coil 3-wire Machines

  • Atlas
  • Bachmann
  • Peco
  • Lifelike
  • Older (Antique?) open frame machines like NJ Industries, Tenshodo, PFM, and others.

Each of these machines can be controlled by a 3-Wire Snap Action Base, but please read the following note:

Important Note About Power

There is an important difference between most equipment now being made, and older designs. Most modern switch machines are being made for digital power supplies that provide 12v DC power. These machines are perfect for our Snap Action Bases with a 12v supply. Most older machines and the older design of model like Atlas Snap Track and Lifelike were engineered for 16v AC power; The standard accessory output of the old non-electronic Power-Pack supplies. Worse, 16v AC actually peaks at over 20v, so these coils really need a lot of “juice” to fire their coils. 12v used on these older designs won’t make them budge.

Fortunately our Snap Action Base was designed to work with up to 24v DC, so all is not lost! The sadder part of this story is that we haven’t been able to get a good supply of 24v power supplies to sell. Our power input jack is a common 5.5mm size and we offer  DC Input Terminal Adapters to connect to alternate supplies. Again, all the details on providing power is available here: About Power For Touch Toggles. We are working on several methods to provide a ready to use solution, and anything we come up with will be posted here.

If you aren’t certain about the best path, we welcome questions at , or call Kevin Hunter at 443 527 6320.


  • Use an Input Splitter to operate two or three outputs together. You can operate a second input on the Direct base, a Relay Base or a Servo Base at the same time for signals, frog power, or anything you might think of.
  • Use a 3-1 Multi-Input Adapter to control any output from two or three Touch Toggles in different locations. Great for two sided operation on peninsulas and modules. All the attached Toggles show the same indication at all times.
  • Use our Toggle Cups to conveniently place single light Touch Toggles in the fascia just below turnouts or controlled accessories. Use these instead of a control panel, or use with  a 3-1 Multi-Input Adapter to offer a second alternative local control.
  • Use 3-Pin Extension Cables to extend your Toggles 20 feet or more. Plug extensions end to end for longer runs runs.
  • Use our 12v DC Power Supply to power your system. All of our 12v Bases have power sharing pins that let each one plug into the next, so you’ll need only one supply at each Base location).
  • Connect your own power supply connections with our DC Input Terminal Adapters.
  • Extend your plug in power supply, or start a power buss with our DC Output Terminal Adapters.

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