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I am part of a local train club that sets up an operating layout for the public to enjoy.  We have it set up in the local mall right now and although we can run 5 trains simultaneously, the highlight is our interactive accessories.  We have numerous pushbuttons around the edge of the layout where children of all ages can push a button and activate an accessory.  Most accessories only operate as long as you hold them in, i.e. a rotary beacon, a crossing gate, a coal loader etc.    However with some accessories, e.g. the MTH gas station, pushing the button once initiates the action.  Nothing further is required until the accessory cycle is completed.  However sometimes if the button is pushed during the cycle, the "brains" of the accessory become scrambled and the accessory locks up.  Cutting off the power to the accessory resets it and it will work properly until the next time.  It is impossible to try to tell kids not to contilually push the button as that is what is required for most accessories.  So what I am looking for is some sort of variable timer (relay?) that, once the button is pushed, will not allow electricity to flow to the accessory again until the timer has expired regardless of how often the button is pushed.  I could time the accessory cycle so that the timer would time out after the cycle is completed.  Can anyone offer a suggestion?  On a related matter will periodically scrambling the brains cause any permanent damage?  Thanks for your help.

 

Don

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See these 2 posts

 

www.jcstudiosinc.com/BlogShowT...=478&categoryId=

 

www.jcstudiosinc.com/BlogShowT...=481&categoryId=

 

Can also make it with a common 555 circuit

 

On the MTH accessories such as the gas station,a little creative latching circuitry with a timer can be made to lock out the button during the cycle. I would have to draw up a circuit,there are many ways to do it. Not sure if pushing the button during the cycle would damage it. If it was designed right no damage should occur,in fact pushing the button during the cycle should not discombobulate it. .

 

Another issue is if the gas station is on the same circuit with other accessories, I would install a TVS on that line to protect the PC chips. PW type accessories can generate damaging voltage spikes.

 

 

Dale H

Last edited by Dale H

Hi Don

 

here is a way to do it using the timers described in the above link. Click diagram to enlarge. There are 2 SPDT relays and a single shot 12VDC timer module. If you do not have a 10 Volt transformer tap,put a 7812 regulator in series.

 

 

P1000350

 

The timer is single shot activated by a trigger so when the button is pushed,let go and pushed again,it does not affect the timer. If the button is continually held,it will not reset until the button is released.

 

When the button is pushed relay one stays on as long as the timer is set for,up to 3 minutes by the timing resistor,a 1 meg adjustable pot. It should be set for as long or longer than the accessory takes to cycle.

 

When relay one is energized,capacitor 2 is discharged into the coil of relay 2. Relay 2 coil is momentarily energized for about 1 second,long enough to pulse the accessory with its contacts. When relay one is off the capacitor is recharged,ready for the next cycle. The 33 ohm resistor slows charge a bit to eliminate spark on the contact points. The diodes across the relay coils suppress spikes. Capacitor C1 and bridge supplies filtered DC to the circuit,about 13 volts with a 10 VAC input.

 

So the button is pushed,relay one comes on,pulses relay 2 which pulses the accessory. After the set time relay one de energizes.

 

The parts to build this is about $25.

 

A 555 circuit can be substituted for the interval timer

 

Dale H

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800-980-OGRR (6477)
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