cncproadwarrior
North of the 49th
What kind of switch do I need to control turnouts?
Spdt? Dpdt?
- Thread starter cncproadwarrior
- Start date
trailrider
Well-Known Member
It depends on the switch machines you are using. Twin coil switch machines require MOMENTARY current applied to them. A Single Pole Double Throw (SPDT), spring-loaded Center-OFF toggle switch or a slide switch that must be depressed to make contact. (Atlas has such slide switches. You slide in one direction or the other and then press down on the slide.)
An alternative to the spring-loaded toggle switches is a plain SPDT switch with a push-button wired in series. You could also use a rotary switch with a push-button in series. The advantage to a rotary switch on your control panel is it will tell you at a glance which route the turnout is aligned to. But you MUST use a momentary push-button in series with the rotary switch or you'll burn out the coils in the machine. Atlas switch machines are this type of twin-coil. Older ones include Kemtron and Tenshodo, as well as PECO.
"Stall" switch machines are set up to maintain their position utilizing a very low current. I haven't used them so I can't tell you much about them.
Double-Pole-Double Throw switches are useful for other things, including reversal of polarity (contacts have to have jumpers wired in an X. Best bet is to pick up a book on model railroad wiring. Even if you are using DCC, such a book (by Lynn Wescott) will get you started.
An alternative to the spring-loaded toggle switches is a plain SPDT switch with a push-button wired in series. You could also use a rotary switch with a push-button in series. The advantage to a rotary switch on your control panel is it will tell you at a glance which route the turnout is aligned to. But you MUST use a momentary push-button in series with the rotary switch or you'll burn out the coils in the machine. Atlas switch machines are this type of twin-coil. Older ones include Kemtron and Tenshodo, as well as PECO.
"Stall" switch machines are set up to maintain their position utilizing a very low current. I haven't used them so I can't tell you much about them.
Double-Pole-Double Throw switches are useful for other things, including reversal of polarity (contacts have to have jumpers wired in an X. Best bet is to pick up a book on model railroad wiring. Even if you are using DCC, such a book (by Lynn Wescott) will get you started.
If you're using Tortoises, you can use either DPDT or SPDT. I think the Model Railroader Magazine site currently has a video showing how to wire a DPDT to reverse polarity. This works if the input power is DC. You can also reverse polarity with an SPDT using "steering diodes" if the input current is AC. Depends on your situation.
Last edited by a moderator:
Yeah, as far as I can tell, he's asking how you control the switch machine from a panel, what kind of switch you use to do that. The DPDT contacts on the Tortoise (or many other styles) are for signals, frog, control panel lights, etc. They wouldn't control the Tortoise itself.
