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auto passing loop control

 
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ruedetropal



Joined: 22 Oct 2006
Posts: 817
Location: Accrington, Lancashire

PostPosted: Tue Apr 28, 2015 8:42 am    Post subject: auto passing loop control Reply with quote

I have used diode controlled auto shuttles for many years. I am planning a small circular layout with a passing loop. I will wire the passing loop with diodes so when power is reversed train will stop and other train move off in opposite direction. The points are sprung so no need to set those .
Now I have done the above before but had manual control. Simple by flicking double pole switch the trains switch, but I want to automate this.
The simplest way I think is using reed switches, but most of the systems I have seen have built in slow down etc which I don't need and make it more complex and more expensive. All the reed switches need to do is activate a double pole switch to reverse power, instantly.
Is there a simple way to wire this up.or unit to buy why just does this?
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Simon Dawson
Will try anything once, looking for the ultimate easy to set up portable exhibition layout, preferably French narrow gauge and with lots going on, not necessary on the rails.

http://www.rue-d-etropal.com
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ruedetropal



Joined: 22 Oct 2006
Posts: 817
Location: Accrington, Lancashire

PostPosted: Thu Apr 30, 2015 9:29 am    Post subject: Reply with quote

I think I might have found something. After talking to a friend, about possibility of using a double pole switch activated by a relay or point motor, I discovered Gaugemaster had introduced a relay with double pole switch built in. All it would need to activate it would be the standard point motor input, is 16v AC.
I am assuming the reed switches Gaugemaster sell can take 16AC through them. They seem to sell packs of the reed switches with an assortment of magnets. I presume its trial and error getting magnets fitted at right height etc. Then I could buy additional magnets to fit to rest of trains.
As the pack comes with spare reed switches(I only need 2 to operate passing loop), I am thinking of various things that could be 'set off' when train passes through the jungle.
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Simon Dawson
Will try anything once, looking for the ultimate easy to set up portable exhibition layout, preferably French narrow gauge and with lots going on, not necessary on the rails.

http://www.rue-d-etropal.com
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CRACKED



Joined: 12 Jun 2013
Posts: 134
Location: Lowestoft, Suffolk

PostPosted: Thu Apr 30, 2015 2:54 pm    Post subject: Reply with quote

I worked out the circuit below before I read your previous text.

You will need to use a latching relay, ie similar to a normal two coil point motor. These normally only require the coils to be activated for a short period of time, otherwise they get hot.

You cannot use Reed switches to directly activate the relay in this application there are two problems.

1. The train will be activating the Reed switch for a long time
2. At one point both switches will be on simultaneously. Trains standing over each switch after the first one has halted and the second not yet started.

I have used a 555 timer in the circuit below.
In order to get over this the circuit given should generate a short pulse of current for about 0.5 s, It will not reset until S1 is released. You will need a duplicate for the other coil.
The diodes are to protect the timer from noise generated by the relay.


Note I haven't tested or built this circuit.




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Clive
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ruedetropal



Joined: 22 Oct 2006
Posts: 817
Location: Accrington, Lancashire

PostPosted: Thu Apr 30, 2015 3:45 pm    Post subject: Reply with quote

Thank you Clive. I will study diagram.
This is the Gaugemaster universal relay unit. It looks like it self protects.The double pole switch is shown changing signal lights, so easy to use it to change polarity. It looks like an ordinary switch to activate changeover.

universal relay
and online instructions
instructions

I was thinking of putting a combination of a point motor , a pair of connected switches to reverse power, and switches to cut power to point motor when activated.
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Simon Dawson
Will try anything once, looking for the ultimate easy to set up portable exhibition layout, preferably French narrow gauge and with lots going on, not necessary on the rails.

http://www.rue-d-etropal.com
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CRACKED



Joined: 12 Jun 2013
Posts: 134
Location: Lowestoft, Suffolk

PostPosted: Thu Apr 30, 2015 9:04 pm    Post subject: Reply with quote

The thing to remember with reed switches is that they ACTIVATED as long as the magnet is present. It is not sufficient to use one relay to change direction and also switch the other one to active, as there would already be a train there which would activate the relay, and switch back and so on. You would have set up what is technically known as a RACE condition, and in this case an actual Race as to which loco can get off the magnet first - there will be a burst of power each time the relay switches.

It would be possible to use another pair of reed switches situated after the entrance to the loop to set the stoppoing reed switch on that side to active, but you then need a 3 pole double throw relay,

Cheers
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Clive
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ruedetropal



Joined: 22 Oct 2006
Posts: 817
Location: Accrington, Lancashire

PostPosted: Thu Apr 30, 2015 10:09 pm    Post subject: Reply with quote

Each loop has diodes on it so trains can only go in one direction on each loop line. It is the diodes which actually determine which train moves.

When train A pulls into loop1, it activates the reed switch which via the universal relay unit switches the DPDT switch, so power to loop 1 does not pass the diodes and train A stops. I am assuming that the relay unit has its's own switch which stops the relay trying to change again whilst the magnet is above that reed switch.
The reversed power then feeds train B in loop 2 which because the diodes are now allowing power in starts to move off.
I could use mechanical liver mini switches which are activated by a physical fitting on each train, or one of the infrared(?) switches.
If the Gaugemaster unit is not capable of doing the above, then I can build the equivalent using Peco point motor and switches.
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Simon Dawson
Will try anything once, looking for the ultimate easy to set up portable exhibition layout, preferably French narrow gauge and with lots going on, not necessary on the rails.

http://www.rue-d-etropal.com
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