Semaphore activation ???

[Anonymous]

I have a semaphore on one track section of my layout. It is activated by a common rail that trips a relay. Problem is when a train is parked on that section of track it keeps the semaphore activated, and I am sure it would burn up after a few minutes.

What,s a neat method to make the semaphore be activated for only a few seconds ?? Is there a way to put a timer in the loop ,or something else that would do the job. Run with it guys.....Thanks..Tim

[wrmcclellan]

Hi Tim,

There are time delay relays available. New they are pretty pricey, but if there is an electronics surplus store in your area, they can usually be had for under $7 - 10. You need the type that activates immediately and then releases after a set delay.

Here is an example:

http://www.grainger.com/Grainger/wwg/itemDetailsRender.shtml?xi=xi&ItemId=1611691480&ccitem=

You would use a 24 VAC transformer (like is used for the thermostat for your AC/heating system) and wire it just like you have your transformer today for the common rail tripping the semophore today. You would use the NO (normally open contacts) contact(s) to control the semophore. You would set the relay to give you the amount of delay you desire (the relays are typically settable for 0.1 sec - 10 sec).

I have used these types of relays for a variety of controls for various layouts.

Bob (Lionelsoni) might have some additional ideas for you.

Good luck!
Roy

[Buckeye Riveter]

And since we are asking, do you guys have other ways to trip a signal other than the common rail method?

[Anonymous]

I have not tried this yet, but this site, http://www.three-rail.com/ has some really neat looking products that would activate accessories for a set period of time, then turn them off, etc. Look at the site, and in particular, check out the Universal Trackside Accessory Controller.

[lionelsoni]

There is a very cheap sort of thermal relay used for sequencing electric furnaces:
http://www.ti.com/snc/pdf/hvactherm-600.pdf

You need one with a 24-volt heater and a normally-closed switch. Apparently they make them that way; but the normally-open version seems to be more common. I have taken a Klixon apart and reversed the little button that operates the switch, to make a normally-open a normally-closed, with very little trouble.

You will need to use 24 volts to operate the relay. A Lionel V or Z can supply this. The 21 volts from a VW or ZW might be enough. But you can probably get a small 24-volt control transformer wherever you find the relay. You will need to reduce the voltage for the semaphore itself. The simplest way is with a series resistor.

[dougdagrump]

Tim, How about using the IR activation devices from Lionel/MTH. Don't they come with an adjustable timing device?

[Anonymous]

Run the semaphor power through the NC contacts of a second 24vDC relay. Put a bridge rectifier and a big capacitor across it so it opens with a delay and breaks the power. Or you could use an interval timer capsule from Artisian controls in line with the relay. These work from 19 to 288 volts and cost about $25.

Dale Hz

[Anonymous]

QUOTE: Originally posted by dougdagrump

Tim, How about using the IR activation devices from Lionel/MTH. Don't they come with an adjustable timing device?

That's a very good question Doug..Maybe someone can answer it. ...Tim

[Anonymous]

QUOTE: Originally posted by Dale Hz

Run the semaphor power through the NC contacts of a second 24vDC relay. Put a bridge rectifier and a big capacitor across it so it opens with a delay and breaks the power.
Dale Hz

Dale, thanks for the reply. I have some 24v relays and bridge rectifiers left over from another project, but I am not sure how you propose to wire it all together. Could you explain it to me a little clearer, so my pea sized brain could understand...Tim

[Anonymous]

Dont know exactly how you are running. On my layout I have a dedicated transformer tap just for relays with a common ground in phase. Activate the new relay coil the same way as the other one I assume using an insulated rail.
Break the hot wire to the semaphore and connect it to the common blade of the new relay contact,then connect the semaphore hot to the normally closed blade. So your power will flow from the existing relay through the new relay then to the semaphore. When the new relay opens up a few seconds later it will break the circuit. Try a 4700 uf 35 V capacitor from Radio Shack they cost about 5 bucks. Should give you enough delay. Make sure you hook up the capacitor correctly. The negative is marked with an arrow and goes to the minus on the bridge. Installed backwards it is a firecracker.

If it is an MTH semaphore I believe it is designed for continuous operation although it is noisy. You may try lowering the power and using DC current,it may minimize the buzz. If the above fails I have an Artisian interval timer I could send you. I use these throwing Atlas turnouts. When I throw a toggle it energizes the coil for a second and cuts power,eliminating accidental coil burnout..The time is set by a fixed half watt resistor.

Dale Hz

[Anonymous]

Thanks for the input guys. I think I will look into this http://www.three-rail.com/ It looks like the most bang for the buck....Tim