On off switches

[37403]

Hi folks,

Looking at wiring up my railway using DC and section switches.

What is the point of on off on switches? I envisaged it would only be useful to have on off switches.

Are they more for two controllers rather than one single?

[Pete the Elaner]

You could use them for choosing a controller. This is often referred to as cab control. If you have 2 controllers, this is much better than driving a train from 1 controller to another.

You will probably want the double pole switches. You can use single if you have common return, but there are extra safeguards you need to follow for this (controllers need to be on isolated transformer coils).

 

[DCB]

I find on-off-on switches a bit of a pain.  We have some and it is not that easy to see when they are "off" compared to simple On-Off switches  Some are sliders and others nice lever switches.   Currently I use rotary switches for selecting controllers, up to 6 can be selected with 2 pole 6 way rotaries and even if you only have 2 controllers it future proofs the set up for if you get more. 

[sharris]

Browsing through the rotary switches at Farnell I see that a lot in the price range that us modellers are likely to afford are rated at 1A DC, so if using them to switch current to track (if you want to switch higher currents the alternative would be using them to control relays to do the switching) make sure you have good short circuit protection in place. 

 

They also typically need a space behind the panel of 26-27mm diameter, so if you have any indicator lights, or other nearby sections that need switches, you will have to be careful to position them far enough from the knob to give the rotary switches room. 

Edited September 2, 2019 by sharris

[cliff park]

Don't forget that there is a difference between switching and carrying. If you operate a switch when current is flowing that is more likely to harm the switch than if you operate it when no current is flowing. It is normal to set up a route, switch the appropriate controllers then start the train. In other words when the switches are operated/set no current is flowing. A switch rated at 1A DC would  carry 3 to 5 A no problem.