Re: Using a three way wall switch to control turnouts

Robert Kenyon

Just be careful you don't wire the switch such that continuous voltage is applied to the switch machine or solenoid.  They can only take momentary current.  Some have contacts in the switch machine such that current is cutoff when the switch operates, but make sure you don't set up such that the solenoid is left energized.  Will burn out in short order.

I use Atlas HO switch controllers on my N Scale layout with exclusively Kato switches.  Using simple diodes, I establish a positive and a negative bus, and run one to each 1 terminal.  The separate third terminal is connected to the switch machine.  The other contact on the switch machine is wired back to the neutral of the DC buses.  Depending on which the position the sliding push button is in, either a negative or a positive current flows through the switch machine when you press down on the sliding push button.  You press down of the sliding push button, and release immediately so no permanent voltage is imposed - only a momentary one.  When you release the button, it springs back to the open circuit position.  You can tell which way the switch is set up by looking at which position the sliding push button is in.

Advantage - Much less expensive than the Kato controllers.  

Disadvantage - Switch position not as obvious to the eye.  Also, diodes will eventually need to be replaced over time.  Could fail in conduct mode but that will be evident the first time you try to operate a switch via the failed diode.  Never posed a problem for me. 

Item - This results in only a half-wave pulse hitting the AC switch machine (on Kato) but I never had a problem with a Kato switch not operating because of inadequate power.

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