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Wiring 4 aspect signals


PaulK
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Hi All,

I want to wire up 4 aspect signals not using a rotary switch under DC, but preferably using a DPDT switch and 'reading ahead' to the next signal. For example - the switch will just give an 'ON' or 'OFF' for the signal, when 'OFF' the aspect will be dependent as to what the next signal is showing - if it's red then this signal would be single yellow, if the next signal is single yellow this signal would be double yellow etc.

 

I saw a pretty good wiring diagram for 3 aspect signalling, but I haven't seen anything for 4 aspects, and I'm not proficient enough to adapt the 3 aspect wiring!

 

I hope one of you clever guys out there can help me, and please, keep it as simple as possible!

 

Thanks all.

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It is somewhat impractical to try to do this using just manual switches.

At the very least, you need to devise a way of interconnecting the signals to produce the required effect on each one.

You will also need a way of detecting where the trains are.

With four aspect signals you are dealing with (at least) two bits worth (I.e. two binary digits) of information to pass from one to the next.

You also need to ensure that each signal prioritises the highest danger level presented to it, i.e. if a train is in the section ahead, the signal protecting it must be set to red regardless of any lower setting being passed back from the signal ahead.

All of this can be achieved in a number of ways, essentially the same in principle, but using different technologies to implement them.

Electromechanical Relays is one solution, but is probably a bit cumbersome.

Hard wired logic, such as TTL or CMOS, is another method which I have used in the past.

Nowadays I would probably use a simple processor like a PIC for each signal, which would have the capability of cascading between signals and driving signal LEDs directly. Again, lots of ways to actually do the information cascading, the choice of which would be down to your own preference.

All of this assumes you don't have a centralised control system available to do the information distribution, such as DCC or MERG CBUS.

Edited by Gordon H
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Richard W of Everard Junction fame, created a video for the control of a 4 aspect signal using a PIC, the youtube video is below; I haven't as yet used Richards method but I think it is jolly interesting.

 

Ian

 

 

 

Edited by Ian_H
Caught out with bad spelling, wouldn’t want to look silly now would I?
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Heathcote Electronics do a 4 aspect signal driver with detector. When several are used together, they communicate with each other so as the 1 clears from red to yellow, the previous clears to double yellow etc. I have seen this demonstrated at an exhibition. I believe these are sold as ready-made instead of kits.

 

If you like electronic kits then MERG have some products which will achieve this.

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There are not enough poles on a DPDT switch to do this so what you are asking for is impossible. It gets extremely complicated when you get to a junction and you have to light the feather as well.

 

To do this on plain track with just switches you would need to use 4PDT switches.

 

In practice it will probably be easier to use 4-pole relays and have some form of occupancy detection rather than using switches.

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If you are looking for manual control of your signals without interlocking of points & occupied blocks then this might suffice.

 

99731544_4astect.jpg.90d7da0966a603faaccb4df2a16e1d62.jpg

 

You will need 3 pole double through switches (3PDT) at least and 1 diode per signal

 

If your signals use leds then don't forget you will need resistors

If the Signals are leds & have a common (+) then simply change the (+) & (-) &reverse the diode 

John

 

 

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I'm so glad I let my automation programme worry about getting all this right leaving me to run the trains - actually I let it runs the trains most of the time also, but compared to wiring these signals it is a dawdle in the park :)

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