Getting a Playmobil shuttle unit to work

[landymad]

More or less....

An attempt at a very simple non technical explanation......

Starting with the transformer speed controller, set direction (personal choice as to whether one chooses forward or reverse) set speed dial for desired level.

The Relay, for those familiar with a DPDT Reversing switch will recognise the similarities in the drawing above, the subtle difference is in the way the "IN" and "OUT" are connected, with a manual switch you the operator physically move the switch, in this instance is is done electronically.

For simplicity sakes will use the contacts "NC" as forward and the contacts "NO" as reverse, or could be reverse and forward.

Track connections BLUE and RED, these can be either one or the other, as in one will be POS the other will be NEG, depending on which way the Relay has been set.

The two diodes, again for simplicity refer to them as detectors, and as above they will either be conducting as POS or NEG.

The Brains is the Quad NAND Gate, which responds to what occurs with the diodes.

So for simplicity at the "A" end, the BLUE wire is POS, upon the Engine passing the diode, a pulse will be triggered to 1 of 4 of the INPUTS to the NAND Gate, which in turn will then activate the Relay, say for argument's sake the contacts will move from "NC" to "NO"

Likewise if the BLUE wire is NEG, upon the Engine passing the diode, a pulse will be triggered to 2 of 4 of the INPUTS to the NAND Gate, which in turn will then activate the Relay, say for argument's sake the contacts will move from "NC" to "NO"

Same and repeat at the "B" end, BLUE wire POS 3 of 4 of the INPUTS to the NAND Gate, and activate the Relay.
"B" end, BLUE wire NEG 4 of 4 of the INPUTS to the NAND Gate, and activate the Relay.

Phew.............

A lot to take in here but I will have a look at the components this week and have a check. Does it matter if the speed of the train ends up sending the train fully past the diode? So it’s be in the ‘dead section’

 

[Software Tools]

Does it matter if the speed of the train ends up sending the train fully past the diode? So it’s be in the ‘dead section’

The loco or powered-car just needs to get fully into the dead section of track at either end, how slow or fast it does that it is not of great relevance

 

[dunnyrail]

I am getting even more confused. But as

The polarity on the track changes, to control the direction of movement of the loco. The diagrams below might help....View attachment 322432View attachment 322433

I am getting even more confused with every explanation though I do fully understand how Diodes work with Positive (red above) power. But as I see the above diagrams it is the Negative (green above) that confuses me or I am not getting simple yes/no answers that I can understand.

1 above lower drawing, negative green on the right passes reverse through the diode? Yes/No
2 above lower drawing, negative green on the left is blocked by the diode? Yes/No
3 thus negative power works exactly to the opposite of positive in a diode? Yes/No.
4 negative power is blocked against the route of the arrow <- blocked to negative? Yes/No

Thanks in advance for suffering my need for answers that Incan understand.

 

[playmofire]

The loco or powered-car just needs to get fully into the dead section of track at either end, how slow or fast it does that it is not of great relevance

Strictly speaking, it's the pickups on the loco which need to get fully into the dead section. So an 0-4-0 tank with all four wheels picking up will need a shorter dead space than an 0-6-0 tank with all six wheels picking up power. A tender loco with pickups on the loco and tender will need to have dead space for both loco and tender.

As regards speed, as the loco/train does not stop dead, there needs to be some space spare in the dead space to take account of this.

 

[landymad]

Strictly speaking, it's the pickups on the loco which need to get fully into the dead section. So an 0-4-0 tank with all four wheels picking up will need a shorter dead space than an 0-6-0 tank with all six wheels picking up power. A tender loco with pickups on the loco and tender will need to have dead space for both loco and tender.

As regards speed, as the loco/train does not stop dead, there needs to be some space spare in the dead space to take account of this.

Yes I’ve just got an 0-4-0 testing the setup at the moment on a 5ft length of track with the diodes across the last join (so last foot or section of LGB track)

 

[JimmyB]

Yes I’ve just got an 0-4-0 testing the setup at the moment on a 5ft length of track with the diodes across the last join (so last foot or section of LGB track)

just a thought, you have power to the "other" last rail, opposite the diode track, and you have tested that the power is there.

 

[landymad]

just a thought, you have power to the "other" last rail, opposite the diode track, and you have tested that the power is there.

I will check this evening

 

[Software Tools]

I do fully understand how Diodes work

It is not complicated .....

 

[dunnyrail]

It is not complicated .....

View attachment 322471

Possibly to you, but that does not help. I understand fully how the positive works, but not how the negative flows.

 

[Gizzy]

Possibly to you, but that does not help. I understand fully how the positive works, but not how the negative flows.

Simply put, there is NO negative flow. Current only flows in the direction of the arrow/triangle and is blocked going the other way. A one way valve in water analogy.

So a DC current is blocked. An AC (sine wave) current would have the negative part blocked so you get Half Wave Rectification.

For Full Wave Rectification, a bridge rectifier of 4 diodes is used. A capacitor is used after the bridge to smooth full wave to a more constant, level DC voltage....

 

[playmofire]

But the good news is that, if like me and others, you don't know how diodes work, so long as you follow the instructions and all is well with the shuttle itself, then everything works.

 

[landymad]

But the good news is that, if like me and others, you don't know how diodes work, so long as you follow the instructions and all is well with the shuttle itself, then everything works.

Sorry I haven’t been in touch Gordon, I’m going to be testing for continuity tomorrow once I borrow a multimeter. (I am still here haha)

 

[playmofire]

Sorry I haven’t been in touch Gordon, I’m going to be testing for continuity tomorrow once I borrow a multimeter. (I am still here haha)

No problem, Andrew, and I hope that you can get th shuttle sorted out. At some time when time permits, it would be good to see the rest of your Playmobil buy.

 

[Paul M]

But the good news is that, if like me and others, you don't know how diodes work, so long as you follow the instructions and all is well with the shuttle itself, then everything works.

For a Christmas gift, my wife bought me an LED lighted tree that with all the components requred. There's clear enough instructions with the comment to check that the various stages work correctly before continuing. Unfortunately it doesn't tell how to fix any problems you might come across though......
TBH, I'm really looking forward to starting it, it's been sometime if been let lose with a soldering iron

 

[Software Tools]

understand fully how the positive works, but not how the negative flows.

There is no "negative flow".... once again, the polarity reverses on the section of track between the diode isolated sections!

 

[-bbbb]

Possibly to you, but that does not help. I understand fully how the positive works, but not how the negative flows.

When the power connects to the rail, the entire rail between the two diodes is electrically considered one point; It will measure practically the same voltage at any point on that part of the rail. The electrons want to go anywhere they can go electrically, but they can not travel across one of the diodes because one will always be backwards in reference to the power source. When the polarity of the power coming to that rail reverses(i.e. the direction of the trains travel is reversed), then the other diode is considered backwards, but the first diode now allows the electrons to pass through. So one diode is always open and the other is always closed, which one is closed or open depends on the polarity of the power between them, and that changes periodically due to the controller.

I think you could achieve the same effect if the diodes were on different rails, but they would need to be facing opposite directions instead of the same direction in that case.

 

[playmofire]

When the power connects to the rail, the entire rail between the two diodes is electrically considered one point; It will measure practically the same voltage at any point on that part of the rail. The electrons want to go anywhere they can go electrically, but they can not travel across one of the diodes because one will always be backwards in reference to the power source. When the polarity of the power coming to that rail reverses(i.e. the direction of the trains travel is reversed), then the other diode is considered backwards, but the first diode now allows the electrons to pass through. So one diode is always open and the other is always closed, which one is closed or open depends on the polarity of the power between them, and that changes periodically due to the controller.

I think you could achieve the same effect if the diodes were on different rails, but they would need to be facing opposite directions instead of the same direction in that case.

I think what you say in your last sentence is correct. On one occasion when I had set up a shuttle I noticed that it was working but the split rails were on different sides of the track. I was puzzled by this but simply altered the track to the correct pattern. Thinking about it, it would mean that the diodes were facing opposite directions when the split rails were on opposite sides. I recently tidied up and can't find my Playmobil shuttle at the moment, but as soon as I do, I'll experiment a bit.

 

[dunnyrail]

When the power connects to the rail, the entire rail between the two diodes is electrically considered one point; It will measure practically the same voltage at any point on that part of the rail. The electrons want to go anywhere they can go electrically, but they can not travel across one of the diodes because one will always be backwards in reference to the power source. When the polarity of the power coming to that rail reverses(i.e. the direction of the trains travel is reversed), then the other diode is considered backwards, but the first diode now allows the electrons to pass through. So one diode is always open and the other is always closed, which one is closed or open depends on the polarity of the power between them, and that changes periodically due to the controller.

I think you could achieve the same effect if the diodes were on different rails, but they would need to be facing opposite directions instead of the same direction in that case.

I think I get it now, my lightbulb moment was a memory of School where we were told to think of Electricity as water going through a pipe. It only goes the opposite way to where the water pressure comes from (+).

 

[landymad]

No problem, Andrew, and I hope that you can get th shuttle sorted out. At some time when time permits, it would be good to see the rest of your Playmobil buy.

Yes definitely, I’m waiting on a friend to get the board checked out by his tutor at college. Failing that I’m going to go to my local model railway club to see if they can suss it out but that’s not until March.

 

[landymad]

Small update but no new news.
The shuttle unit has taken a backseat for the past few weeks until last weekend when I decided to have another look.
I noticed that the solder for the diodes hadn’t stuck as well as I thought (due to me not heating the rail enough.
Anyway I got the rails removed and soldered diodes properly. Checked both diodes that the train stopped once it had passed then I could manually drive the train out with the controller.
Had circuit board checked by friends tutor and he said it all seemed to test well and he couldn’t see any problem with it.
I’ve just put it all back together and tested and I’ve still got the same problem as before.
So back to the drawing board or wait until the open day at the local g scale club in March.