Switching/diode matrix question

[spikey]

 

That's the five storage loops which form part of my new fiddle yard. The points are operated by SEEP solenoids, and I'm at the stage where all this part of it works, with all leads going back to a tag board where the control panel will be. I now need to crack on with the panel itself.

 

I've never used a diode matrix before, but thanks to the help I got here with my earlier question about controlling the two three-way points, I'm confident about knocking one up give me push-button selection of the top three loops. What I'm scratching my head about now is the two bottom loops.

 

I can see how I could develop a matrix for all five loops, but I really don't fancy firing more than 4 solenoids at any one time. So how might I do the switching to the bottom two loops?

[johnb]

Why not do the matrix in two sections? One for each end, that's how we work one of the club's fidde yards, so two buttons per loop.

 

John

[Suzie]

Four should be feasible with a big enough CDU and fat enough wire, so have a separate matrix for each end.

 

It is only the bottom two at the right end that have four motors, all the other routes have just one, two or three.

[spikey]

Gosh, thanks ever so much folks. I would never have thought of that! My bit of Veroboard and my diodes came yesterday, both outputs from the CDU to this area are 32/02 and I'm assured by the makers that firing four SEEP solenoids simultaneously won't be a problem, so all I have to do now is work up to fathoming out the matrices ...

Edited September 11, 2018 by spikey

[NinOz]

Many years ago I abandoned the single central CDU in favour of individual DIY CDUs for each point motor.

Number to be thrown at once is no longer a problem and long runs of thick cables no longer necessary.

 

Something to consider.

[DCB]

Its best to design to equalise the number of points per road.   However I have done the opposite with a loop FY in adding two dead end sidings to the shortest loop so trains can run into the siding, and set back straight into another siding before departing. It means the shortest loop can hold the longest train. It needs both sidings as setting back round curves is challenging

 

 

 

Many years ago I abandoned the single central CDU in favour of individual DIY CDUs for each point motor.

Number to be thrown at once is no longer a problem and long runs of thick cables no longer necessary.

 

Something to consider.

Not sure how you integrate Diode matrix with individual CDUs.  I would be interested in how this could be achieved.   The individual CDUs would surely need two (three)  individual wires back to the panel.  I use matrix's as close to the points as possible, actually on  the baseboard. with one wire per route from the panel plus one return. CDU can be either end, panel or baseboard.

I balance the load on point motors by ensuring that the same number of points as near as possible throw at the same time. 5 is currently my max, 3 minimum and as only two move together in a crossover I added a dummy motor, half a burned out point motor as a "dead load" to get to 3. It was going to be 2X dead loads to make 4 but it works ok. Previously the shock of changing was working the point blades out of the stretcher.

[naugytrax]

 

"Not sure how you integrate Diode matrix with individual CDUs."

 

Here's one method which has been found to be successful and reliable:

Each of the individual CDU's has 4 terminals:  common negative, positive 20V for charging the capacitor, and one control input for each direction. Each control input grounds the base of a general purpose transistor, which turns on a Darlington pair which connects the capacitor to the turnout motor in the desired direction. Leads from the CDU to the motor are thick but just a few inches long. The Diode Matrix, on the control panel, has one input per route and two outputs per turnout motor as usual. However, since the (microscopic) current is flowing from the transistor base to the negative supply, the diodes are wired the other way round from usual.  Together with direction indication leads from switches on the turnout motors (using the same common negative), the system uses 6 wires per turnout, but since the currents between control panel and CDU are small, six-wire telephone cable is quite adequate and the cable runs can be neat.

[Suzie]

The normal method of using multiple CDUs is to just common the switch feed (and optionally the power feed if run from a common power source) between the CDUs and run the common wires from the point motors back to the local CDU. 

[Andy Hayter]

Just to say that I have a six road fiddle yard x 2 (up and down) run through a diode matrix and CDU - so 5 switches operating.  So far no failures.

 

The entry and exit are separately controlled as suggested above.  This allows entry to one line and simultaneous exit from another, which might be an advantage depending how you want to operate.     

[ELTEL]

I’m in the process of designing and building a small micro layout similar to the track plan of Dock Street featured on RMWEB

 

Mine will be a Industrial setting based on a small cement works

 

It will in reality be a Inglenook puzzle with a extra point in throat area of the layout of a left hand point for diesel refuelling point not to be used in shunting manoovers.

 

I will be using Peco Code 75 and it will incorporate a three way point to save on space.

 

I wish to use a push button system for selecting points.

 

My question is I have found in the past guest operators struggle with three way points, so I want a electrical circuit diagram so when they set a route that incorporates the three way point it will change both set of point blades in the correct order with one press of the button..

 

Eltel

[Andy Hayter]

The quick and dirty way to do this on the mimic is to treat the three way point as two, two way points - which in fact it is.

 

Buttons will be close together, but so what

[newbryford]

I’m in the process of designing and building a small micro layout similar to the track plan of Dock Street featured on RMWEB

 

Mine will be a Industrial setting based on a small cement works

 

It will in reality be a Inglenook puzzle with a extra point in throat area of the layout of a left hand point for diesel refuelling point not to be used in shunting manoovers.

 

I will be using Peco Code 75 and it will incorporate a three way point to save on space.

 

I wish to use a push button system for selecting points.

 

My question is I have found in the past guest operators struggle with three way points, so I want a electrical circuit diagram so when they set a route that incorporates the three way point it will change both set of point blades in the correct order with one press of the button..

 

Eltel

 

 

If it's a asymmetric 3-way, then 3 buttons, 2 diodes and a CDU. (4 diodes if you want t 

Simples.

 

Buttons left/middle/right.

Two motors are bottom (at toe end), top - nearest the frog. Bottom motor direction is right/straight, top motor direction is straight/left

Left button feed left top motor and straight bottom motor via a diode

Middle button feeds straight top motor and straight bottom motor via diode.

Right button feeds right bottom motor.

 

I'll draw you at diagram at Warley!

 

Cheers,

Mick

[ELTEL]

If it's a asymmetric 3-way, then 3 buttons, 2 diodes and a CDU. (4 diodes if you want t 

Simples.

 

Buttons left/middle/right.

Two motors are bottom (at toe end), top - nearest the frog. Bottom motor direction is right/straight, top motor direction is straight/left

Left button feed left top motor and straight bottom motor via a diode

Middle button feeds straight top motor and straight bottom motor via diode.

Right button feeds right bottom motor.

 

I'll draw you at diagram at Warley!

 

Cheers,

Mick

Mick

 

Your a star

 

Eltel

[DCB]

If you treat the FY as two halves so you can have simultaneous arrivals and departures you get into problems in DC /Live frog with section breaks.  The incoming point needs to feed the whole section as does the outgoing so you need extra switching as if you have a simple insulated rail break and loco length or two short of the exit end the loco will short it out as it bridges the rails to the live frog.  I have this issue on my FY and have yet to find a really acceptable solution and currently set the points at both ends to the same road as a temporary solution implemented 20 years ago

Edited November 25, 2018 by DavidCBroad

[Suzie]

The traditional solution to this is to treat the frog switching and power routing as two separate things and have a double pole switch that throws with the point so that one pole switches the frog and the other pole provides the power feed. You just come unstuck if both ends are set to the same road when using separate controllers for arrival and departure - but that should not happen!