Manchester Central, CLC & GN Warehouses & Castlefield Viaducts

[GJChurchward]

Ron,

 

Since the faces of your theatre displays are simply plates with a matrix of holes drilled into them, I wonder if you really need to use multiple fibre optic strands?  Have you considered using segment displays (assuming you could find them the correct size)?  You'd still get light shining through the correct combinations of holes.  It might be difficult to adjust the brightness, but it would be a lot less hassle putting them together.

 

Andy

[Ron Heggs]

Ron,

 

Since the faces of your theatre displays are simply plates with a matrix of holes drilled into them, I wonder if you really need to use multiple fibre optic strands?  Have you considered using segment displays (assuming you could find them the correct size)?  You'd still get light shining through the correct combinations of holes.  It might be difficult to adjust the brightness, but it would be a lot less hassle putting them together.

 

Andy

Hi, Andy

 

The smallest displays available would be suitable for 7mm scale, but not 4mm scale

 

Hassle ? Don't know the meaning of the word

 

A challenge - Yes - But no more than building fully detailed working semaphore signals

 

Cheers

 

Ron

[Shadow]

Well, you can surface mount LEDs down to 0.8mm x 1.0mm (smallest I could find for white, yellow is down to 0.4mm square!)

 

Now that  would be a challenge.

 

Dave

[Stubby47]

With the fibre optic leads, one source bulb can light many of the output positions at the same time - individual LEDs would need one for each position, therefore a different diode matrix and more complex wiring.

 

I think...

 

My concern would be light bleed between the tightly packed fibre optic leads.

Edited November 22, 2013 by Stubby47

[Ron Heggs]

Well, you can surface mount LEDs down to 0.8mm x 1.0mm (smallest I could find for white, yellow is down to 0.4mm square!)

 

Now that  would be a challenge.

 

Dave

Hi, Dave

 

That was my first option, but the challenge of soldering all those LEDs in such a tight array has been put on the backburner for the moment. A etched PCB would be needed to hold and supply the 35 LEDs and the associated leads

 

Cheers

 

Ron

[Ron Heggs]

With the fibre optic leads, one source bulb can light many of the output positions at the same time - individual LEDs would need one for each position, therefore a different diode matrix and more complex wiring.

 

I think...

 

You are quite right

 

If I was going for a production model then the design would be to provide individual LEDs for each fibre optic strand for a full alphanumeric display, and a much more complex diode matrix

 

 

My concern would be light bleed between the tightly packed fibre optic leads.

 

 

That is a separate challenge, yet to be tackled and solved

 

Short strands could be sorted ok, but the strands for the displays on the gantries would be upto 350mm long with four changes of direction, and of course no sharp curves

 

The routing of the strands is yet another challenge - 62 strands for the outward routes on the West Gantry, and 60 strands for the platform routing displays on the East Gantry. The strands for Platform Starter displays will be much shorter being routed directly under the baseboard

 

... and that is in addition to the 18 leads on each of the gantries for the LEDs in the various 2 & 3 aspect and shunt signals

 

Did someone mention 'Spaghetti Junction' ?

 

Cheers

 

Ron

[artizen]

Good luck!

[Shadow]

Hi, Dave

 

That was my first option, but the challenge of soldering all those LEDs in such a tight array has been put on the backburner for the moment. A etched PCB would be needed to hold and supply the 35 LEDs and the associated leads

 

Cheers

 

Ron

 

But it would mean less wires (fibres). Only need 12 wires for one, then an additional 5 per extra indicator.

 

Edit :- Plus a bit of extra electronics to drive it of course.

Edited November 22, 2013 by Shadow

[Ron Heggs]

But it would mean less wires (fibres). Only need 12 wires for one, then an additional 5 per extra indicator.

 

Edit :- Plus a bit of extra electronics to drive it of course.

Hi, Dave

 

I would be interested in how this logic would work

 

Ron

[Stubby47]

Hi, Dave

 

I would be interested in how this logic would work

 

Ron

 

Ron,

 

In both arrays, you've already decided which of the individual 'lights' is to be fed by which LED, via th efibre optic leads. For example, LED #1 will feed the first 4 positions down the left side of the matrix.

 

So, if you replace the single LED #1 on your diagram with an array of LEDs, each one positioned in the appropriate place as you've previously decided, then your logic and diode diagrams are correct as they are and you should not need any more electronics.

 

Stu

Edited November 22, 2013 by Stubby47

[28XX]

Is there perhaps a small back-lit LCD display which could have a perforated black mask placed in front?

[Ron Heggs]

Ron,

 

In both arrays, you've already decided which of the individual 'lights' is to be fed by which LED, via th efibre optic leads. For example, LED #1 will feed the first 4 positions down the left side of the matrix.

 

So, if you replace the single LED #1 on your diagram with an array of LEDs, each one positioned in the appropriate place as you've previously decided, then your logic and diode diagrams are correct as they are and you should not need any more electronics.

 

Stu

Hi, Stu

 

That's how I produced the PCB drawing logic, but it needs 14 wires - 1 for each of 13 LED sets plus the common return

 

Not sure why or how an additional 5 wires per extra display are needed

 

Ron

[Ron Heggs]

Is there perhaps a small back-lit LCD display which could have a perforated black mask placed in front?

There are just no displays of any type small enough

[Shadow]

You use an array that's set out in rows and columns. One wire per roe, one per column.The

Each LED is connected to one row and one column.

 

I'm just trying to do some drawings. I'll post them in a minute. Not easy to put into words!!

[Shadow]

Each led is connected to one row and one column

 

 

Each matrix will have 7 columns and 5 rows , ( or 5 x 5 for the smaller one)

 

The column controls can be common to all matrixs.

 

 

This gives the 7+5 for one, and then 5 for each extra matrix

 

 

The secret is too pulse each of the rows/columns in the right sequence. if this is done fast enough, the appearance is that they are on all the time.

 

You put the supply to each column one at a time, and then ground out the row of the corresponding led to illuminate it.

 

 

Dave

Edited November 23, 2013 by Shadow

[Shadow]

Something similar, but with a scrolling message using a Raspberry Pi here

 

 

14 x 9 display

[Ron Heggs]

Each led is connected to one row and one column

 

led.png

 

Each matrix will have 7 columns and 5 rows , ( or 5 x 5 for the smaller one)

 

The column controls can be common to all matrixs.

 

led 1.png

 

This gives the 7+5 for one, and then 5 for each extra matrix

 

 

The secret is too pulse each of the rows/columns in the right sequence. if this is done fast enough, the appearance is that they are on all the time.

 

You put the supply to each column one at a time, and then ground out the row of the corresponding led to illuminate it.

 

led 2.png

 

Dave

Hi, Dave

 

Thanks for this info. I did understand your previous post re. matrix arrangements

 

What really puzzles me, is how the timing is arranged (possibly some kind of timer and shift register), and characters are formed (software ?). Does this mean that microcontroller/s is/are required ?

 

I can understand the theory, but not the practice

 

Are there any documents/literature that could show me what is needed, and how to put it all together?

 

Cheers

 

Ron

[Shadow]

It can be done with simple 74 series ICs  and a timer chip (i.e. 555)

 

The timer causes the counter to step through.

The lower 3 bits of the counter are used to set up the row  states.

the upper 3 bits are used to set up the column count.

This gives a maximum of 8 rows per column and 8 columns.

The reset is set to restart the counter back at zero when the limit has been reached.

 

The 74138 3 to 8 decoder converts the 3 upper bits into individual column discretes

The 74148 8 to 3 Encode converts the switch selection for the required display character into an address, that along with the lower row address bits, indexes into the prom to get the correct row discrete output.

 

The red box components can be repeated for additional indicators required

 

 

PROM details

 

 

This is not a fully working circuit, as enable lines, reset lines, power, etc have not been shown.

Also, values of data for PROM may need to be changed depending upon which row and column you call 0!

You will also need to check drive capabilities for the types of LEDs used.(Current drain, etc.)

 

Dave

[Dagworth]

Ron, 

If you can get hold of a copy of Roger Amos' Model Railway Electronics the matrix display is described in it

http://www.amazon.co.uk/Complete-Book-Model-Railway-Electronics/dp/185260591X

or http://www.amazon.co.uk/Complete-Book-Model-Railway-Electronics/dp/1852602880

 

Andi

Edited November 24, 2013 by Dagworth

[Shadow]

http://www.kingbright.com/attachments/file/psearch/000/00/00/TA03-11GT(Ver.5A).pdf

 

Just came across this really small dot matrix display.

 

unfortunately, it only comes in green or red,

 

Display size is 7.6 x 5 mm. (Correct size)

Package size is 18.5 x 9.8 mm (Not correct size!!)

 

Dave

[Ron Heggs]

http://www.kingbright.com/attachments/file/psearch/000/00/00/TA03-11GT(Ver.5A).pdf

 

Just came across this really small dot matrix display.

 

unfortunately, it only comes in green or red,

 

Display size is 7.6 x 5 mm. (Correct size)

Package size is 18.5 x 9.8 mm (Not correct size!!)

 

Dave

Hi, Dave

 

Thanks for all your help. Will need to get to grips with this subject

 

The display size is just right, but the package size is too big

 

Cheers

 

Ron

[Ron Heggs]

Ron, 

If you can get hold of a copy of Roger Amos' Model Railway Electronics the matrix display is described in it

http://www.amazon.co.uk/Complete-Book-Model-Railway-Electronics/dp/185260591X

or http://www.amazon.co.uk/Complete-Book-Model-Railway-Electronics/dp/1852602880

 

Andi

Hi, Andi

 

Thanks - Have ordered the first edition, and if that is a little long in the tooth in some departments, will order the 2nd edition. Delivery expected by Dec 10th

 

Will now need to get up to speed with the latest electronics

 

Cheers

 

Ron

[two tone green]

There are white versions here. Click on the green down arrow for options.

 

http://www.forge-europa.co.uk/components/dot_matrix_displays/5_x_7

 

I have used this company and found them to be very good.

[Grovenor]

The smallest one from forge-eur would be ideal for 7mm but oversize by quite a lot for 4mm. Pity because a 7x5 matrix with the 7 vertical was pretty much the standard for route indicators, those needing to display two letters such as DM etc usually used two indicators side by side, and a special 7x7 matrix unit was available for applications such as terminal approaches where numbers were required up to 19.

Keith

[two tone green]

It may be worth talking to them as they do custom build LED's.

 

I has a 45 minute chat with one of their tech guys and came off the phone with some very useful info and with them making some white seven segment displays for me.