Fastrack Switches for Power Routing?

Probably not a contact on the bottom of the switch, but you could rig a relay module to the switch position output pin to close when it's either positive or negative, depending if you're looking for power when the switch is in the thru or out position.  A series diode will block the opposite polarity from the switch module.  Typical modules sell for a buck or two on eBay.  eBay: 273056055027 looks like it would do the job.  You'll need 5VDC to power the module, a cheap wall-wart supply would do the trick for a bunch of these.

Thanks so much John.  

Which pin is the switch position output pin?

Here's the switch position output pin, it outputs a low current +/- 5VDC logic signal based on switch position.  I believe the + is thru and the - is out.  This is used to drive the LED's in the remote lever, or any other bi-color LED on a control panel.

John,

Again, thank you so much!  I googled this issue for a number of days with no success which I found surprising since it’s so useful.  Eliminates having to have a separate power switch for each stub in a yard.  Just set the switch to out and you have power and are ready to start the engine and move the train out. For a somewhat remote yard with a lot of stubs, it saves a lot of wire pulling.

-Richard

Glad to have an easy solution.   Of course, you do sort of need a power supply, you need the 5V power for the relay module, and you can power many modules with the same 5VDC supply. 

You can also buy the relay boards with multiple relays on one board if you want to control power to each stub independently based on the switch position for that particular stub.  I'd also get one or two of the relay boards and experiment to make sure you have a working solution.  It looks good, but the Chinese don't give you much data on the actual signal requirements, so it's an educated guess based on my experience with similar boards like that and what the Fastrack switch outputs for the light feature.

Is there a similar way to do this with the venerable O22 switch with only 3 connections or would you need to break into the housing to solder leads to part of the moving mechanism or use a mechanical lever switch?

Well, the switch does have feedback to light the remote lights for direction, but for a foolproof method, I think it takes two inputs.  Since the switch can hang up in the middle with no lights lit, I'd think that would have to be accounted for.  Of course, if your switches are working properly and you trust them, you could just key off one of the lights to operate the relay. 

Kirk R posted:

Is there a similar way to do this with the venerable O22 switch with only 3 connections or would you need to break into the housing to solder leads to part of the moving mechanism or use a mechanical lever switch?

If you don't mind some DIY, here's an idea:

Use a relay module as GRJ suggests.  These run less than $1 per relay on eBay (free shipping from Asia).  A 4-channel module shown in photo so this one could power 4 stubs.  There are modules that have 1,2,4,8,16 relays.  This particular module requires 12V DC.  You can generate 12V DC from 14-16V AC Accessory voltage with an AC-to-DC converter module which are less than $3 on eBay (free shipping from Asia).  You could alternatively use a 12V DC output wall-wart if your yard is near an AC-wall outlet.

You trigger a relay by apply a trigger voltage.  But these are DC relay modules.  In general you cannot apply an AC voltage as a trigger.  And you'd get an AC voltage from an O-22 switch terminal.  While there are countless methods to convert AC to DC, one trick would be a light sensor that aimed at the stub bulb.  So when the bulb in the switch-lever-controller turns on, the light sensor trips and triggers the relay.  The relay applies power to the stub/diverge track.

Light sensors are tiny and inexpensive (maybe 10 cents each).  You could wire the sensor inside the switch-controller aimed at the stub bulb.  If that is inconvenient, you could wire up a 2nd bulb in parallel with the stub bulb right at the switch-terminals.  This slave bulb could then run under the layout and placed in proximity of the light sensor. 

No offense Stan, cut I think I'd just use a diode, capacitor, and a 5V 3-terminal regulator to generate the "logic" signal for the switch.  Also, the bulb in the 022 switch is on all the time, the only bulb that switches for the O22 switch is the one in the remote control switch.  Just by tying the three component circuit to the 022 switch control terminal and ground, you have a bullet-proof logic signal to indicate the switch position.

No offense taken.  I meant aiming the light sensor at the stub/diverge bulb in the lever-switch remote assembly (not the always-on lantern at the switch itself).  Of course if this is remotely located it would make wiring complicated.  In that case, just power a bulb from the appropriate 2-screw-terminals at the switch itself.

It's that fussing with the AC-to-DC conversion which can require tinkering to get it right.  If you have a 12V DC wall-wart, then the diode-cap-regulator method is fine because of the electrical isolation afforded by the wall-wart.  But for the case where it's inconvenient to pull wiring or there is no AC wall-outlet handy, you'd probably derive the relay DC supply from Accessory AC or whatever is powering the O22 switches.  For powering multiple yard relays, you'd probably use an AC-to-DC module where the outer-rail ground is no longer relay ground.  This could be an issue with the diode-cap-3-terminal regulator method of generating the "logic" signal.  For example, while many of the eBay relay modules use optoisolator in their title, and you can even see an optoisolator chip on the trigger signal, they actually don't have optical isolation.

Since the 022 switch control terminals are common ground to light the lights, I don't think you'd absolutely need total isolation, though it's never a bad idea.  The logic signal I'd be be generating with the regulator approach would also be ground referenced.

I'm confused about the isolation issue, the relay contacts are surely totally isolated from any of the logic side, I guess I'm not seeing that I'd have a problem with the O22 switch scenario I painted.  Clearly, I could be overlooking something, and I trust you will point it out if I am.

Given the relatively low current draw of the relay modules, you could get tricky and just power the 5V supply with the same power and just tie the logic input to the power supply.  Anytime the light lit, the relay would be picked. 

You could just use the regulator and a 5V coil DC relay, no relay module required.  eBay: 192396674665 for 77 cents, shipped free.

There certainly are a lot of ways to skin this cat.

The isolation issue is only if you use one of those $3 AC-to-DC regulator modules that has a bridge rectifier.  In which case the DC power to the relay module would have a different ground than the "logic" signal you generate.  If you use a wall-wart to generate the DC for the relay module then no problem.  Correct, not referring to the isolation on the relay output side.

One comment though - if dropping from 14V AC to 5V DC, that's a lot of wasted power.  And for those "blue" eBay relays, the 5V coil current will be more than double the 12V coil current.   Hence, if directly powering the relay from the switch's AC power, I'd consider using 12V relays.

Like you say many alternatives.   

Good point on the 12V vs 5V relays, since we're drawing the power through the switch coil in this scenario, the 12V ones would be a better choice.  Also, you could likely dispense with the regulator, just a diode and cap in front of the relay.  Dirt simple and dead reliable.