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Author Topic: Point wiring conventions.  (Read 193 times)

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Offline Old Crow

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Point wiring conventions.
« on: August 06, 2019, 07:59:18 PM »
I've a number of points to wire up and a decent 4x 4700mf CDU running off a Gaugemaster 16v transformer. I'm going to link all the return connections on the point motors so as to just need two signal wires to each from the control switches. I've been told that you should not make the common return link as a continuous loop (ie returning whence it came) is there a reason for this and what is the common practice when wiring up points?

Online ntpntpntp

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Re: Point wiring conventions.
« Reply #1 on: August 06, 2019, 08:51:33 PM »
I normally run my common return as a daisy-chain along all the point motors for each baseboard.

I can't think of any reason why you couldn't run the common return as a looped circuit if you wanted to, but I've never found it necessary. It's not like there is constant current flow all the time so you don't need to worry about splitting the current round both ways of the circuit as you would in a ring main.
Nick.   2016 celebrating the 20th anniversary of "Königshafen" exhibition layout!

Offline PLD

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Re: Point wiring conventions.
« Reply #2 on: August 06, 2019, 08:52:34 PM »
I've a number of points to wire up and a decent 4x 4700mf CDU running off a Gaugemaster 16v transformer. I'm going to link all the return connections on the point motors so as to just need two signal wires to each from the control switches. I've been told that you should not make the common return link as a continuous loop (ie returning whence it came) is there a reason for this and what is the common practice when wiring up points?
The perceived concerns about a complete "ring-main" arrangement possibly have some validity for the phases of an AC current (such as a DCC command signal) getting out of sync on a very long loop.
The output of a CDU however is always DC...

Online ntpntpntp

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Re: Point wiring conventions.
« Reply #3 on: August 06, 2019, 09:00:20 PM »
The perceived concerns about a complete "ring-main" arrangement possibly have some validity for the phases of an AC current (such as a DCC command signal) getting out of sync on a very long loop.
The output of a CDU however is always DC...

Would have to be a *very* long ring main to see any noticeable phase effect at all. Think about it, your average house ring circuit is longer than the wiring on a typical layout.

Sometimes I do wonder where some of these strange ideas and concerns originate?
Nick.   2016 celebrating the 20th anniversary of "Königshafen" exhibition layout!

Offline Malc

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Re: Point wiring conventions.
« Reply #4 on: August 06, 2019, 09:35:37 PM »
I think some of these ideas about looping DCC bus wires stem from networking. If you loop a network cable Network adapters get 2 signals overlapping and they don’t like it up em. However network signals are many orders of magnitude higher in frequency than DCC at 15k.
The years have been good to me, it was the weekends that did the damage.

Offline Old Crow

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Re: Point wiring conventions.
« Reply #5 on: August 06, 2019, 10:14:42 PM »
Thanks guys, my return circuit will be a loop with the odd spur - after all it's just back to zero. The +dc out of the CDU will go through the centre tabs of all the momentary on-off-on switches I have.
My Gaugemaster transformer has two separate 16v outputs - any ideas what I can do with the other and I note my Combi control which does everything I need at the moment also has a 16v output.

Online ntpntpntp

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Re: Point wiring conventions.
« Reply #6 on: August 06, 2019, 11:14:13 PM »
My Gaugemaster transformer has two separate 16v outputs - any ideas what I can do with the other?
Well I would use one for the CDU supply and one for lighting and other accessories.

Of course the other output could be used to power a second controller in the future.
Nick.   2016 celebrating the 20th anniversary of "Königshafen" exhibition layout!

 

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