Wiring Seep Point Motors, Switches and a CDU - help needed.

[Andy 17]

I'm just starting the electrics on my layout. I have 8 Peco electrofrog points which are controlled by Seep PM1 point motors. I'm also using a Gaugemaster CDU unit. 

 

I've been testing each one of the points as I install them and they all work fine.

 

On/Off/On switches are being used to change the points.

 

I understand how to connect them individually but I'm a bit confused as to how to connect them all together to the CDU using the (Red) wire that goes from the positive of the CDU unit to the centre of the switch. Can I run the wire from the CDU unit and use "dropper wires" to the other switches?  (in a similar way that the (Black) negative wire runs from the CDU to the "C" connection of the point motors).

 

This is a diagram I've found on the internet.

 

Best Wishes

 

Andy

[Pete the Elaner]

What do you mean by 'dropper' wires?

Some refer to 7/0.2 wire as 'droppers', but others may use 16/0.2 for the same task.

Ideally you want to use wire which is the best conductor (fattest) possible. Using thinner wire is always a compromise on space, cost & workability.

 

Many recommend 16/0.2 for all solenoid point motor wiring because any current passing through the coil passes through all parts of the circuit to get there.

While I agree with this as a recommendation, I have used 7/0.2 without trouble although I have no longer cable runs where the wire's resistance may become more of an issue.

[RobinofLoxley]

But to answer the question, that wiring diagram is absolutely correct. For the avoidance of any doubt the switches should be momentary on - off - momentary on with sprung centralisation.

 

On my last layout I had 40 switches mounted onto a board and the lower supply soldered across the central contact of each switch in turn.  But if you are intending to mount the switches in more individual locations, you can run the power supply wire how you like from the CDU terminals. But use reasonably good cable on the power supply side, more important as the distance from the CDU to the switch increases.

 

You can use common return with the CDU as well.

[Andy 17]

@Pete the Elaner and @RobinofLoxley I think I may have confused us all by not asking the question correctly, for which I apologise.

 

I'll have another go!

 

The bit I'm unsure of is how to connect the CDU positive to each of the switches. On the wiring diagram there looks to be a wire going to the centre of each switch and then one wire going away from it to the next one. What I meant by saying "dropper wires" was; can I have one wire going from the CDU and wires going from that wire to each switch - much in the way "dropper wires" go from a bus wire. 

 

Or could I use one of these terminal blocks and connect the CDU to the first terminal on the bottom left and then connect each switch to terminals 2 to 9 along the bottom?  The red bar at the top connects all 12 terminals together. I have used them for my bus wires and my dropper wires.

 

The switches I'm using are the momentary on - off - momentary on with sprung centralisation type.

 

I hope that is a better explanation of what I'm trying to work out.

 

Best Wishes

 

Andy

Edited January 6, 2021 by Andy 17

[Brian]

Yes you can do that.  (Its my web sites drawing BTW)  You're looking at using a sort of common positive CDU bus connector then from that wired to each switches  middle tab from the connector.  No problem.   But do ensure the feed wire from the CDU to the Bus and those from the bus strip to the switches are in at least 16/0.2mm equipment wire or a larger wire size where two motors are to operate from the one switch.

 

You can do the same out on the layout-in several places if need be and connect each Seep "C" pad to the common connector, linking one connector to the next. So as one wire feeds from the CDU output negative to the first strip then on to the next strip and so on until the last one is reached.  Again ensure feed wire from CDU and linking connector is large enough wire size. I would use 24/0.2 minimum and each motors "C" connection to the common connector in 16/0.2mm.

 

BTW the point switches need to be non locking sprung to centre off type.  Not the type that can remain in the On position when the switches lever is released.  These sprung switches are frequently called (On)-Off-(On) type where the bracketed On can't remain in that position.

Edited January 6, 2021 by Brian

[John ks]

Adding to previous posts, I find images easier to understand

Below are 3 versions of the red wire 

All are electrical the same, you could even mix the versions 

 

 

 

Hope this helps

John

[RobinofLoxley]

Maybe underlying the question is a concern that not all switches would receive the same power from the CDU if activated simultaneously or nearly so, depending on how the power lines are distributed? Well there is no need to worry about that as long as you use the switches correctly.

 

When I was building my last layout, I tested each point motor in place with a portable rig, so no more than 30cm of wire all told. Then the PM's were wired back to the main switch bank which was up to 4M of cable on the supply side and potentially the same on the return; this included points in pairs. I used whatever cable I had handy, and never had any problems with function. But if you can respect Brian's recs'  do so.

 

And yes, using your analogy of bus distribution, you can do that for the supply from the CDU to your PMs.

[Andy 17]

@Brian @RobinofLoxley @John ks Thank you all for all your help, it is very much appreciated. I  can approach the wiring with a lot more confidence now.

 

Just to confirm, I am using the non locking sprung to centre off type of switches. Each switch will only control one point motor.

 

Best Wishes

 

Andy

[RobinofLoxley]

Thats the correct switches. You can choose to have each switch control only 1 but with a CDU you can switch more, your choice

[LimboBrit]

2 hours ago, RobinofLoxley said:

Thats the correct switches. You can choose to have each switch control only 1 but with a CDU you can switch more, your choice

On a previous layout I did route selection with a push to make switch which reliably switched 4 point motors simultaneously via a diode matrix

[Brian]

When using a suitable CDU and input power supply you should have no problems with either Push to Make non locking press buttons or Sprung to centre Off Toggle switches or even good old fashioned Stud & Probe selection.

However, do ensure if operating two or more solenoid motors from one switch/PB or Stud & P that you ensure the feed wires are robust in wire size.  My recommended minimum is always 16/0.2mm especially for Seep motors that are quite power hungry!    

Where two (or more) solenoids are operated together from one switch etc then increase their shared common return wire to a absolute minimum wire size of 24/0.2mm and better if 32/0.2,

 

All this increased wire sizes ensures 100% operation, whether one or more solenoid motors are moved at once.