Reed switch question

[FRRYKid]

I don't know if this is the right forum for this or not, but here goes: Has anyone in the forums ever worked with reed switches? What I would like to do is rig up a circuit to light my MDC 34' Overton cars. (They are an older version of the new Athearn Overtons marketed by Horizon Hobby.) I would like the lights to trigger only when the train goes into tunnels and shut off when they exit the tunnels. The only way that I can think of to do this and keep the circuit as small as possible would be a reed switch. An example of the switch of the one I am looking at is located here
. The attached file is a diagram of the two circuits. One of which is for my crew cars (combines with the seats operating forward (single light) and the other is for the rest of the cars (two lights).

Just in case the picture doesn't show, this is a link
to the picture

[FRRYKid]

http://inmemoryofpage.org:2082/cpsess1213950437/frontend/x3/filemanager/showfile.html?file=Circuit-Diagram.gif&fileop=&dir=%2Fhome%2Finmemory%2Fpublic_html&dirop=&charset=&file_charset=&baseurl=&basedir="
is the link for the circuit diagram http://www.ebay.com/itm/260772004527?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1424.l2649
is the link for the reed switches. Sorry, about half the time even when I use my visual editor, I can't get links to work.

[claymore1977]

A few things. 

1) Check out tinypic.com They allow you to upload a picture onto their servers and provide you with a simple URL.  Makes image sharing really really easy.

2) Reed switches might work, but I am uncertain if the train moving will cause any problems.

3) How about a photocell or phototransitor?  When it gets 'dark' a photo cell could turn on the lights in your car.  This would also make the on/off functionality work outside of tunnels if, for instance, the room lights dimmed to the correct level of darkness.

http://home.cogeco.ca/~rpaisley4/PhotoDetectors.html

[nedthomas]

A few years ago some mfg made passenger cars with battery lighting controlled via  a reed switch. You passed a wand over the roof to turn the lights on/off. For this you need a "latching reed switch". i.e. the reed stays in the last position operated. This can be done two ways-mechanical or bias magnet. In the mechanical method the reed will toggle to one side unitl the magnet is reversed and toggle to the other side. With the bias method a small magnet is placed next to the reed - not strong enough to operate unitl a external manget is applied. when the external magnet is removed the bias magnet will latch the reed. Reverse the external magnet to un-latch the reed. Reed switches are hard to find in todays solid state world. Also operating distance is usually 1/2" or less.

[Mark R.]

My immediate thought on this this is, why ?  Can you see your train when it is in the tunnel ?

On my layout, I can't see my train when it is in any of the tunnels, so I wouldn't know if the lights are on or not !

Mark.

[rrinker]

 Or just have them on all the time, if they are kept to a reasonable brightness instead of being toy train bright, they won;t be glaring in the open yet visible in the dark. Real trains didn;t turn the lights on and off when they went in tunnels.

           --Randy

[FRRYKid]

The reason why I want to have the cars lit in the tunnels (there will be 2) is that I am trying to echo a dinner train I rode on a few years ago. When the train went in the single tunnel on the line, the passenger cars lit up. When the train left the tunnel, they turned off. Given that this train only operated during daylight hours, just having the cars light for the tunnel makes sense to me.

As for the picture, I have a website that I run that makes linking pictures easier so I don't have to use another site to store pics.

Let's try the circuit picture link again:

Top part is for the crew cars. Bottom is for the rest of the revenue cars.

I found a listing for latching reed switches. It is eBay item #230899818211. For what has been described, I think this would be the correct switch. Given I can't seem to get a link to the proper page built, I will list the item number.

As for the operating distance, I had the thought of embedding the magnets in the top of tunnels to activate the lights.

If there is anything else anyone needs to know, please let me know.

[nedthomas]

Don't know about the E-bay item. Even the guy selling them says they don't work every time.

[maxman]

FRRYKid

The reason why I want to have the cars lit in the tunnels (there will be 2) is that I am trying to echo a dinner train I rode on a few years ago.

I'm afraid I have to agree with Mark R., above.  I understand trying to duplicate that dinner train, but the only reason you know the lights went on in the tunnel is because you were riding the train.  Anyone not on the train wouldn't know if the lights were on or off in the tunnel.

So, unless you have a camera in the tunnel, it seems like extra effort to make something happen that won't be seen by anyone.

[jrbernier]

  You might want to check out Miniatronics - They have 1 amp capacity reed switches for model railroad applications.  Walthers stocks them....

Jim

[Robert Frey]

Get a reed switch and a magnet that can operate the reed at a reasonable distance.   Say about 0.1”  Now put  a magnet at each end of the tunnel in the center of the track.  One reed under each car can receive an “On pule” at each end of the tunnel.  Now find yourself a electronic circuit where one “On pule” turns On a light, and one “On pule”  turns Off a light.  (A one button operated Toggle circuit.)  Now you fine that one, and you got a system that can work the way you want it. 

Bob Frey   

PS: Same idea.  Put an IR Diode and each end of the tunnel.  One photo cell bottom of each car.  (Photo cell operated Toggle circuit.)   

[gmpullman]

Hi Kid,

I have a few of the Rapido passenger cars that use just the kind of reed switch you're looking for. NOW Rapido is offering just the lighting kits in their "Easy Peasy" line. Maybe you could move the reed switch or keep it near the roof depending on the strength of the magnet. You could mount your magnet on the arch of the tunnel portal or do some soldering and move the reed switch(es) down to the belly of the cars and use a magnet between the rails.

Look here for one example... read the reviews. Sounds like some users are doing exactly what you are looking for.

http://www.modeltrainstuff.com/Rapido-N-102021-Easy-Peasy-Passenger-Car-Light-p/rpi-102021.htm

Here's the Rapido site...

http://www.rapidotrains.com/light_ho.html

On the downside, unless they use a different LED now my Rapido cars have yellowish/green LEDs! Yuck! Some day I may get around to replacing the LEDs with white or golden-glo's.

In my days of messing around with LGB trains they had an extensive setup of reed switches and relays available that could activate signals and relays or switch motors. Fun stuff! But the magnet was on the underside of the locomotive and the reed switches clipped between the ties. IIRC they were SPDT so you could use the NC or NO contacts.

Hope this helps...

[wjstix]

In theory the OP could do what he describes. I recall someone had their layout set up with reed switches in their passenger cars and cabooses in such a way that as a train left staging a magnet turned the lights on, and another magnet turned the lights off as a train headed back into staging.

However as noted, I don't see the purpose of turning the lights on when in a tunnel so you can't see them.

I've installed reed switches in passenger cars in the past, to control lights powered by batteries inside the cars. It worked fine, but in future I'm probably going to use DCC track power and TCS accessory decoders with the "keep alive" technology instead.