Film-Tech Forum ARCHIVE: Model train question for you electronics experts

This is topic Model train question for you electronics experts in forum Film-Yak at Film-Tech Forum ARCHIVE.

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Posted by Mike Blakesley (Member # 26) on 09-13-2005, 04:52 PM:

We put up a big Lionel train layout at my day job every Christmas. The only bad thing about this layout is, it requires someone to run it.

I would like to add one or two small loops of track (independent of the rest) where a kid could walk in, press a button on one of these loops to make the train run for a few minutes and then shut off automatically. (A pushbutton switch with a time-delay.)

What kind of a device would I need to do this? We have an account with WW Grainger, so if anyone has a Grainger catalog and could provide an item number, I'd be grateful.

Posted by Andy Muirhead (Member # 712) on 09-13-2005, 06:47 PM:

Mike, we actually have this kind of setup running at my cinema. It's a Harry Potter display with the Hogwarts Express, built and designed by our retired Chief and Boss of all things, who also is a model railway enthusiast. Setup is same as described by you, most of the track is live, and one section (hidden by a tunnel) is on a time delay relay.

When somebody presses the button, the 'not live' section is powered and the train runs, doing a few loops until the time delay kicks in again, thus powering off the rails while the train is in the hidden section again.

Unfortunately I am off for a few days and can't remember exactly what kit he used, It was from RS components and along the lines of the type of kit to keep your interior car lights lit for a period after you had left the car, that sort of thing. If your still stuck in a few days, I'll let you know exactly the kit he used once I get back to work!

Posted by Bruce Hansen (Member # 281) on 09-13-2005, 06:54 PM:

If you are into soldering, you can use the good old 555 timer IC. Have it drive a relay, which turns the power on and off to the tracks.

If you want to make it more interesting, use a light beam switch to start it when anyone walks through the beam.

Posted by Phil Hill (Member # 371) on 09-13-2005, 08:38 PM:

Mike, if you just want the train to run for a pre-determined time only and not re-cue to a specific place on the closed loop, it's very easy to do. It is very similar to the automatic delay for a lamphouse exhaust blower when the lamp is shut off. The only desired difference for your train is you'd would like a "non-retriggerable delay off" time delay relay. The non-retriggerable one is desired so that if some smart-ass keeps pushing the trigger "Run Train" button, the cycle will not start over each time the button is pushed, but will time out in the set time period from the original push during the time period.

(A lamphouse blower would like a re-triggerable delay relay in case the lamp is turned back on during the off-timing cycle which would allow the timing period to start over when the lamp is shut off again.)

While I don't know the specific Granger numbers, they do stock the type of relay you need. The relays usually are time-adjustable within a range with a knob and come in an octal plug-in package. A specific example for your application relay is:

Where the trigger is connected to the "Run Train" button and the N.O. contacts are connected to the supply line voltage and connect to the train transformer that is preset to the desired train speed.

Note that the relay must be powered all the time so that the trigger can be recognized and there is voltage to activate the internal relay contacts.

Hope this helped.

Posted by Daryl C. W. O'Shea (Member # 1303) on 09-13-2005, 10:07 PM:

Depending on your current requirements you might be able to use a solid-state time-delay relay that's worth about $5. For higher currents, you're probably looking at a $65 mechanical version.

Posted by Mike Blakesley (Member # 26) on 09-14-2005, 02:06 AM:

Sounds good. Now that I at least know what I'm looking for maybe I can find it in the Grainger book. Thanks guys.

Posted by Mark Hajducki (Member # 1732) on 09-14-2005, 08:08 AM:

If the section of isolated track is short then a simple 'push to make' switch would work (since most kids will press and hold the button). (The timer switch would be usefull if you want the train to make multiple circuits of the track)

Mechanical (mains voltage) time delay switches are avaliable which may work well. (These are often used in comunal stairwells and able to withstand abuse) Example

Posted by Mike Blakesley (Member # 26) on 09-14-2005, 12:54 PM:

It needs to be a timer-type thing because I don't want kids to pound on the button repeatedley and have the train stop and start. I want it to keep running for a few minutes after the button is pushed.

Posted by David Buckley (Member # 2600) on 09-14-2005, 04:06 PM:

If time is more important to you than money, or you really dont want to cut veroboard, the easiest solutions is a micro-PLC. There are many manufacturers, including Crouzet Millenium, Siemens Logo!, and more than a dozen others.

They are easy to program using the onboard LCD. One thing that springs to mind is that they have a real time clock in them as well, so your train doesnt need someone to switch it off at night. Attach a security system PIR so that when therre's no-one around for a few minutes it shuts down, saving wear and tear.

These little things are wonderful. Sure, its a more expensive solution than a timer relay, but a load more versatile.

Posted by William Hooper (Member # 71) on 09-15-2005, 12:49 AM:

How about one of those clockwork-spring timer wall switches such are used in hotels for the mysterious red bulb in the bathroom? One might be found locally at a Spa & Tub dealer, & it could be mounted in a quad box with an outlet into which the train transformer could be plugged.

Here's a toggle-type electronic version at Grainger for $26.00 Turn it on, it stays on for 15 minutes or until you turn it off manually.

The $50 version can be set for a duration of 1 minute to 18 hours.

The rotary types are available for different durations; this one is 5 minutes max.
this one also is 5 minutes max, but has a 'hold' feature so you can optionally turn it on & leave it on.