Diode matrix for storage yard points.

[peterm1]

Hi,

Old member just rejoined and I have a problem. I'll attach (I hope) a drawing of my yard points. I'm using Tortoise motors and a bi polar supply to switch them with rotary switches. I decided to start afresh with a new layout and instead of taking a photo or two of how I'd wired them in the first place, I went all gung ho and now can't remember how I did it or how to do it again..Getting silly in my old age.

Help with this will be greatly appreciated.Yard diagram.pages.pdf

 

[Nigelcliffe]

Try this page which goes through it, pretty much identical to your track diagram: 

 

https://www.trains.com/mrr/how-to/build-model-railroad/design-procedure-for-yard-ladder-control-using-tortoise-switch-motors/

 

 

This has fewer parts and wires, but there are other issues to think thorough
 

http://davidksmith.com/modeling/articles/article-4.htm

 

 

Edited December 26, 2022 by Nigelcliffe

[DCB]

Dooplickit

Edited December 27, 2022 by DCB

[peterm1]

Thanks for the replies. I'll have a look later because I now have to go for a 40 minute drive to an Optus shop, because they've lost my details!  Sorry just letting off the steam of frustration.

[DCB]

it's not clear from the OP how the  points are to be operated,   I use a Rotary switch but mine are solenoid motors so the Rotary selects which  road to set the  points for and there is an additional push switch to energise the motors.  With stall motors or slow action switch machines similar wiring would need a push to break switch to prevent the motors moving as the rotary switch passes over their contacts.     

 

16 hours ago, Nigelcliffe said:

Try this page which goes through it, pretty much identical to your track diagram: 

 

https://www.trains.com/mrr/how-to/build-model-railroad/design-procedure-for-yard-ladder-control-using-tortoise-switch-motors/

 

 

This has fewer parts and wires, but there are other issues to think thorough
 

http://davidksmith.com/modeling/articles/article-4.htm

 My matrix are pairs of wiring connectors with diodes strung between, the diodes have insulated sleeves over their bare  wires.  Zero soldering, easy alterations or replacements.

 

You could not reasonably operate this layout of points with solenoid point motors and a diode matrix, though with slow motion ones its fine though a waste of space.  I use so only a max of 3 motors fire together not 4 and there is more siding space for the same length.  see pics

 

For the OP matrix connections see other pic   Actually 1L / 2L/ 3L / 4L and 4R don't need diodes just plain wires

[peterm1]

That looks like even I'll be able to follow it. I'm having problems with adblock plus interfering with the forum even though I've turned it off for this site (whitelisted). So if I don't get back to you straight away, you know why.

[ikcdab]

I am an evangelistic convert to servos.  The 90g type cost about £2 each and you need a driver of which there are many different types.  I use MERG servo4. Mounts are home made from plasticard, though there are many different homemade solutions available.  Then all you need is a single wire to trigger the servo from a simple on/off switch. I also use a diode matrix and a rotary switch to select the route that then throws ask the required turnouts.  See control panel below. As it's a single wire only, the diode matrix is fast simpler than with solenoids.

If using commercial points then thats all that is required.  My handbuilt points require polarity switches and I use miniature relays.  In this case I use a double switch such that one side operates the servo and the other the relay.  It's more simple than it sounds here!

If the OP (or anyone else) wants more info, then just ask!

Ian

[peterm1]

Thanks. I have Tortoise motors in abundance also good quality rotary switches from NSF in England. I've got 5 pole wafers, pos' one side and Neg' the other along with 5 pole mechs on which I can stack wafers. My only problem is that my poor old brain's showing it's age and the wiring of these sidings/yards is driving me nuts.

 

Ps: Smart panel. 😀

Edited December 27, 2022 by peterm1

[ikcdab]

2 hours ago, peterm1 said:

Smart panel

Thanks.  I designed and built it as you can see then realized that I had done it all upside down!  So I had to scrap this one, rejig the graphics, reprint and rebuild it all.  

[peterm1]

Thanks to Nigel, DCB and IKCDAB. Someone on another forum came up with the method he used and how I did it last time round. I've done one side of the yards, I can now do the other side and I won't be losing the drawings this time.

 

Your assistance is much appreciated.

[ikcdab]

3 hours ago, peterm1 said:

Thanks to Nigel, DCB and IKCDAB. Someone on another forum came up with the method he used and how I did it last time round. I've done one side of the yards, I can now do the other side and I won't be losing the drawings this time.

 

Your assistance is much appreciated.

Can you post a link to the other forum? I'm always looking for interesting things to read.

Ian

[Michael Hodgson]

On 27/12/2022 at 11:55, ikcdab said:

Thanks.  I designed and built it as you can see then realized that I had done it all upside down!  So I had to scrap this one, rejig the graphics, reprint and rebuild it all.  

Couldn't you just invert the lettering on the graphics and turn the whole panel upside down?

[ikcdab]

47 minutes ago, Michael Hodgson said:

Couldn't you just invert the lettering on the graphics and turn the whole panel upside down?

There are holes drilled through the diagram and the backing aluminium sheet. I attached the diagram to the sheet with heavy duty double sided tape.  Given that the holes were already drilled, it would have been very difficult indeed to line up the new diagram such that the marks on the diagram lined up with the predrilled holes. Far less heartache to just start again!

Edited December 29, 2022 by ikcdab

[peterm1]

22 hours ago, ikcdab said:

Can you post a link to the other forum? I'm always looking for interesting things to read.

Ian

I'll ask the op if that's OK with him.

[peterm1]

6 minutes ago, peterm1 said:

I'll ask the op if that's OK with him.

Waiting for a reply.

[Simon G]

My MRC has a very similar problem to the OP.  We have a layout where a single line runs into 5 roads in the yard (see pic).  The turnouts are operated with Peco point motors, and are switched with simple non-latching momentary toggle switches.  The power to the motors is via a Gaugemaster CDU.  We have 5 switches, one for each road.  It was originally wired up with push button switches, which werent reliable, and in a major rewiring, we are struggling now to use a single switch to set each road.

 

My current plan is that to go into the top road, we just need a switch without diodes to operate turnout P1.

For the second road, we operate P2 without a diode, but P1 will require a diode.

Likewise for the third road, P3 doesnt need a diode, but P1 and P2 do.

Again for the fourth road, P4 doesnt need a diode, but P1, P2 and P3 do.

For the fifth road, I think that all P1 to P4 will need diodes.  This means that we would need 10 diodes for the arrangement shown.

 

 

The existing wiring is current a real muddle, so my plan is to put all these diodes onto a piece of vero board.  I assume that the copper on vero board will be able to handle the current involved in operating the Peco motors?

 

I have looked at the pages referenced earlier in this thread, and although the use of additional switches reduces the number of diodes needed, I think that the wiring will be eaiser using diodes than the use of SPDT switches.

 

Does this seem a sensible way to go, or is there a simpler or more elegant way of using the diodes?

 

 

[Chris M]

My way is simple but certainly not elegant. It has however withstood 6 exhibitions without giving any problems. Changing a diode should be just a screwdriver job.

 

[Simon G]

That is an impressive layout!  I wish that I had the space (and funds!) for something like that.  
 

As you say, by using chocolate block connectors instead of vero board, it does away with the need for soldering and makes replacing any bits much simpler.  As the MRC has a load of used chocolate block taken from a dismantled layout, I might use that instead.

[ThePipersSon]

The wiring for a diode-matrix is shown in the book 'Electronics and Wiring for Model Railways' by Andrew Duckworth.

Unfortunately, there are quite a few errors within the book so beware. For the diode-matrix, the section is meant to show what is required for a diagram on page 100, but the text refers to the diagram on page 27, with the same layout but different point numbers.

Still, you should be able to discern what is required.

 

Tom

[Brian]

This may help?  Link to Diode Matrix 

Blowing own trumpet now!

[multivac]

I seem to remember a company supplying a PCB drilled with a matrix of holes and linked by tinned copper traces. Links were made with a nut and bolt. Diodes were also included but I don't remember if they were fitted in production or by the purchaser. Seems ideal to recreate using the cheap online PCB suppliers that are around nowadays.

Edited March 24, 2023 by multivac

[DCB]

On 31/01/2023 at 10:42, Simon G said:

My MRC has a very similar problem to the OP.  We have a layout where a single line runs into 5 roads in the yard (see pic).  The turnouts are operated with Peco point motors, and are switched with simple non-latching momentary toggle switches.  The power to the motors is via a Gaugemaster CDU.  We have 5 switches, one for each road.  It was originally wired up with push button switches, which werent reliable, and in a major rewiring, we are struggling now to use a single switch to set each road.

 

My current plan is that to go into the top road, we just need a switch without diodes to operate turnout P1.

For the second road, we operate P2 without a diode, but P1 will require a diode.

Likewise for the third road, P3 doesnt need a diode, but P1 and P2 do.

Again for the fourth road, P4 doesnt need a diode, but P1, P2 and P3 do.

For the fifth road, I think that all P1 to P4 will need diodes.  This means that we would need 10 diodes for the arrangement shown.

 

 

The existing wiring is current a real muddle, so my plan is to put all these diodes onto a piece of vero board.  I assume that the copper on vero board will be able to handle the current involved in operating the Peco motors?

 

I have looked at the pages referenced earlier in this thread, and although the use of additional switches reduces the number of diodes needed, I think that the wiring will be eaiser using diodes than the use of SPDT switches.

 

Does this seem a sensible way to go, or is there a simpler or more elegant way of using the diodes?

 I missed this post, .
The diode matrix won't work with the proposed wiring.   The CDU won't shift all those points, two should be OK, but more than three solenoid  point motors thrown  will definitely need an upgrade.  My experience is a CDU which throws five points damages a single one if you just try to throw one.   You could put P2 in the straight road behind P1 so at most 3 throw together or use  more than one CDU but it won't work as the op describes,

Edited March 24, 2023 by DCB

[DCB]

1 hour ago, multivac said:

I seem to remember a company supplying a PCB drilled with a matrix of holes and linked by tinned copper traces. Links were made with a nut and bolt. Diodes were also included but I don't remember if they were fitted in production or by the purchaser. Seems ideal to recreate using the cheap online PCB suppliers that are around nowadays.

You can use a PCB.  I prefer hardboard.   Two wiring connector strips, and diodes strung between. The diode's bare wires need sleeving, I use insulation from 5 amp mains wires, I did my first setup  about 30 years ago  and it's never given any trouble, if it did every diode can be undone simply by just unscrewing two screws, no soldering, and the hardboard is just screwed to the baseboard framing.  No soldering.... No expensive PCB.

[ikcdab]

I've just come back to this topic and thought i might contribute again.

The first thing with a diode matrix is to work out a truth table whch shows which routes require which turnouts for your fan of sidings:

In this case, N - Normal and is when the points lie for the siding. R is reverse and is when the points lie for the next line.

 

The next step is to work out the wiring from this:

 

Note that the push buttons could easily be replaced with a rotary switch. 

This then leads to the veroboard layout - if you want me to draw that out then just let me know and I can do it.

 

 

Edited March 25, 2023 by ikcdab

[DCB]

That is good for the OP 2which uses tortoises but not the later Simon G post where he uses Solenoids. See my post 20.28 Friday

Edited March 26, 2023 by DCB