I am having difficulty finding a suitable switch to protect my train from entering a block when the bridge is up. It is a DCC layout so a double pole switch is needed. I cannot find a double pole microswitch and I’d rather not implement a relay.
What do you use for this purpose?
BB
Hello Bruce,
You can use two microswitches to serve as a double-pole switch. Microswitches are generally built to be mounted in sided-by-side stacks, so there’s no need for them to be made in a double-pole configurations.
Good luck with your bridge,
Andy
Andy, thanks for the reply. Have you tried reed switches? I was considering them because I will hold the bridge down with rare earth magnets. Mounting could be a problem though.
BB
Reed switches could work, but make sure the contacts are rated for the amount of current in your track. Actually, you really don’t need any kind of premade switch to do this. Just make your own contacts that attach to the bridge. Bridge closed, circuit closed, no big deal.
I’ve a similar problem, Bruce, with my gate, the tracks either side need to deadened or a short on them so if the gate is open a loco or an MU situation will stop before the gap!!!
Reed switches will work but they should probably switch relays so the current can be handled.
The new MR mag has a switch/relay circuit for doing this.
I think if a short section is isolated from the rest of the layout either side of the gap, and is switched by the gate/bridge switches, it should put a short circuit on the track, so a train approching will trip the (in my case the DCC booster) and stop the train.
I must make this a priority on my layout because it’s to easy to leave the darn thing open!!
Ken.
Why do you need a double-pole switch? DC or DCC, the track is dead if either rail is dead. SPST should suffice for a cutoff.
Good point, kill one rail, and the trains stop.
Bruce, is this bridge a detailed model, or is it an enterance to the layout with roadbed? I’m curious if the switch needs to be hidden or pretty, or just functional.
My safety interlocks are a pair of barrel bolts. power from the booster comes in one side. if either bolt is open there is no power to the track anywhere. the bolts and hinges are the main part of the bus
The bridge is the entrance to my layout but I still want to hide the switches. I’m not quite sure what is meant by “bolts” and how they could be used to break a circuit. I also am basically opposed to applying a short circuit every time the bridge is open. The booster crowbar circuiit is reliable only up to the point of complete failure.
BB
To my way of thinking, you should never “short” circuit anything. The switch should make an “open” circuit (no connection). I agree with Mister Beasley and Big_Boy_4005 in that you only need a single pole switch to open the circuit to one of the rails.
Tom.[:D]
I am not sure what happens inside a decoder when only one rail is openned. Seems like an unbalance of some sort. Where is Rinker when you need him?
LOL
BB
Nothing, there is no current flowing since the dead rail does nothing but make an incomplete circuit. No difference then disconnecting one wire from the power source.
Hi Bruce. Dont know if there is a Radio Shack in Canada, Perhaps a micro switch would work for you. If you still have the pictures I sent you, I use the power lead to dissconect the last three feet of both sides, is easy to set up, and one has to pull the plugs before moving the the lift up anyway, cant forget it and there is no adjustment to worry about. I try to keep things as simple and as bullet proof as possably.
Email or send a pic…would love to see it, take care…John
Why not use a Twin-T activated by the microswitch – bridge open, switch open (no current to bases and therefore no current collector to emitter); bridge closed, switch closed (current to bases activates circuit collector to emitter)?
How about trying a mercury switch? (Operates on motion)
When the bridge is down the switch contacts are closed.
When the bridge is up the switch contacts will be open.
Yes, Radio Shack exists across Canada. They will have the same products as their U.S.A. stores.
Ther is no need to break both rails in a DCC powered model railway. One rail without power will stop any train approaching a lift out, a drop down or a gate entrance to your mdel space. Thus a SPST switch will work just fine.
I have a trio of tracks (one through and two on top) that cross my gate entry. Each track is protected on each side of the opening by a Radio Shack micro switch that has its operating finger depressed by the closing of my gate. Only when the rails are in alignment do the switches close to activate the track power. A small screw can be mounted on each end of the gate opening to fine tune the closing of the circuit should the benchwork move due to expansion/contraction of the material due to temperature and humidity changes. The unpowered section of track on either side of the gate is about three feet long to protect any moving train from disaster.
Actually, Radio Shack doesn’t exist in Canada any more. Radio Shack Canada was owned by Tandy Corp. who was recently bought out by Circuit City. Radio Shack wouldn’t allow Circuit City to use the Radio Shack name or sell Radio Shack products. Now, all the former Radio Shack stores are called The Source by Circuit City. They still sell most of the products that don’t have the Radio Shack name on them, including electronic parts, so you won’t notice too much difference, but they are stocking more higher end consumer electronics.