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I've decided to split this into 3 as I haven't quite finished yet, but want to start sharing.

Part 1 Introduction, pulls together a few links from earlier posts and introduces the main components & issues.

Part 2 The Electronics

Part 3 The End Result.

I have allready posted on how I fitted the digital controll board on the Car chipping thread.

http://www.slotforum.com/forums/index.php?...=8621&st=15



Next I started looking into the Brake lights on the Le Mans 1966 Gt40 MKII.

Here is a link to the thread, am still not certain why some have 2 red rears and some a red & amber.

http://www.slotforum.com/forums/index.php?showtopic=8927



I have decided to assume that the lower ones are combined Rear & Stop lights. If anyone knows better, shout fast.

First step was to remove the lower lenses as I intend to replace them completely with Led's Then I drilled through 3mm from the outside and 4mm from the inside to allow the Led to protrude the correct amount.



So next on to the LEd's. After much searching I have chosen some Cylindrical 3mm through panel LEDs from Kingbright part No. L-1334SRT

They are a fraction small, but have the look of a rear light and are sufficiently bright. I sourced them from Rapid Electronics in the Uk @ 11p each.



Here they are in situ.



So thats it for now, here is a shot of the test bed for the electronics.



Part 2 how it works and how to wire it up next.....
 

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Part 2 The electronics

The electronics are simple, but not for the faint hearted if you are not used to soldering small components.

I am sorry if this is a bit trivial for some people but I guess we have a wide audience here in electronics terms, so I have tried to spell it out.




First on the left is the Saloon board.
We will be connecting wires to BK (Blue) Square Pad
HL (Red) Square pad
The circular pad next to BK (Green)

On the right you can see the wires connected



This is the circuit diagram with the same connections.

How does it work?

Green is Ground or 0V.

(HL) is intended for Headlamp connection. I am using this as the 5v supply for the Rear lights. This is connected with the Red wire through a 4K7 (4700) ohm resistor through a yellow wire to two Led's connected in series, the other end of the Led's goes to ground completing the circuit.

4K7 was chosen to give the desired brightness of rear lights and can be adjusted to your taste.

As soon as the car is put on the track the rear lights will come on with the headlights.

The diode (almost any diode can be used here, looking at Maplin 1N914, 1N4148, 1N4001 are all well over what we need, we are only taking 5mA) It connects to BK via the Blue wire. It serves to isolate BK from HL however it drops far less volts then the resistor so when the brakes are applied the brightness of the Led's increases.

In order to function you will need to select Braking On the control unit. If you select Dynamic or Both this means that in practice when you put the car on the track the Brake lights will come on immediately, driver has foot on footbrake.


As soon as the controller is depressed the brake lights go out leaving the rear lights on. Braking at the end of the Straight will of course bring them on again.


So thats how it works. In the final part we will connect it all up and go for a drive.
 

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Discussion Starter · #4 ·
So an interim post. Thanks for the feedback Ian, glad someone is interested in this. You have me spot on. By Boxing day all toys had been disassembled. By new year they had been modified.


Just wanted at this stage to post a warning.

This use of the motor control board, has no support from Scalextric. There is no instruction from them as to how to do this. It has been worked out by reverse engineering and guesswork.

I am confident that it will not harm the board. The Microcontroller outputs that are bing used are rated at 25mA and we are taking 5mA in brake mode & 1mA in rear light mode.

Some may feel that we have enough unsolved problems with controller boards without this. They are right.


Think carefully before proceeding.
 

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Part 3 Putting it all together

First job is to solder the resistor and diode to the leads coming from the controller.



They will tuck down the passenger side. A piece of heatshrink over the diode and then another piece over the pair of them. Will shrink down later.

Next we need to wire up the Led's and fit into the rear.



Green and yellow as in the diagram. Brown wire joins the two Led's.

Not pictured but a few drops of Superglue used to secure the Led's and wires.



As the rear and base are separate parts I have put joins in the wires to make assembly easier.

Finally what do they look like.




Engine off........................................................................light
s on..........................................................................Brak
ing Hard

Thats all folks, may try and do a video, what do you think?

Richard
 

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Discussion Starter · #8 ·
Hi Maltese

I have absolutely no connection with Scalaxtric. I suspect they dread my every post.


I just enjoy working out how things work, then adding and improving. Slot cars happens to be getting my time at the moment.

The Aux port was there for the taking, and the Brake lights were likewise. I suspect intended for future enhancement.

No mention in the documentation, but the latest boards were even marked as you can see, although I had found it before then. Have been dropping hints in posts for weeks.


No flicker from the brake lights, expept when the driver indulges in a bit of left foot braking.
 

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Good Morning Guys

Thanks for the nice comments, makes it all worthwhile.

Headlights if the car has not got them already can either be connected across the slot guide or connected to HL. But we must be carefull how much current we take, so I would recomend the Slot Guide.

Whats Analog? I am not sure but I think that Brake lights will be on permanantly. Will check and report back

Trouble is I have got another 5 to do, the first one is fun, but once you have proved the point, the rest are a bit less interesting. However they do look so much nicer than the Audi's, so will have to knuckle down.

I may go to the trouble of measuring the leads so that they can be made externally and just fit, that would probably help everyone. (but only for a GT40)

So had quite a long play in different light levels and I think the brightness is about right. If anything the brake lights are more light rear fog lights, but because they are only on briefly this is needed or you loose the effect.

They are sufficiently bright that they create a sheene on the track as if the track is wet at the end of the Mulsanne straight.


If you want to reduce the brightness level of the brake lights just put a resistor in series with the diode.

So we have heard from the "(B)leading Edge Team".
Would be interested to know what other people think.

Is this a modification you would consider?
If not why not?
Would you the mechanical bits if a wiring assembly was available?
Any other thoughts or comments?
Any other electonic features or gizmos you'd like to see in the car?

I have to say that Scalextric has got it nearly right again.

We have here a digital controller and digital light board for £11. That is fantastic value for money if you compare it with just the Slot.it lighting board at £14

The mistake, well the same one as the board itself, no plugs and sockets to make it easy to use, oh & they forgot to tell us.


Now I have toyed with Yellow Led's in the exhaust pipes that flash on briefly as you lift off
I think Slot.it do this
or is this an Led too far.
 

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Yes I knew that.


The F1 boards almost certainly have the brake / headlamp signals available on the chip. To save space they have omitted the 150 ohm resistors & connection pads. I guess F1 cars don't have lights.


I will confirm this for reference at some point.

I am only using the HL connection as a convenience, you could take that signal from the 5v line.

I tested the lights in Analog mode, the rear lights not the brake lights are on permanantly and vary in brightness, but thats analog for you.


Anyone with chip failures have a look at the F1 run stop / ID change thread, more input needed.

Richard
 

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Discussion Starter · #16 ·
I have no mini.
However I would be amazed if there was not a way of doing it.

Don't quite understand the question, there is no rear light circuit board as such, just a couple of components and the Led's?

Can you post a picture?
 

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Discussion Starter · #18 ·
First just to confirm what I have done and therefore tested.

I left the headlights in the GT40 unchanged. Connected to the slot guide. There seems to be a diode and then a series resistor for each headlamp. This means that they will be seeing as you describe a rectified square wave which will give less brightness than DC.

I have not tried them on an Analog track so do not know what they look like. They did seem a bit dim, but I just assumed that they were like that. I did quickly hook the car up to DC, but it was not on the track (at 12v) and they did not seem much brighter.

Will take a further look at this.

Two possible solutions.
Modify the headlamp board, replacing the single diode with a bridge.
Rum them from the HL output of the digital board.

For the moment I would recommend leaving them on the slot-guide. Need to make some measurements of current and check the capability of the 5v regulator on the control board.

When hooked to the digital board or driven off the slot guide, lights do not vary in brightness.

There is probably some degree of filing that an Led can stand before damage is done. However they are available in a lot of shapes and sizes. I would recommend looking for ones that are the shape you require.

There are some nice examples in the Overdrive range.

http://www.professormotor.com/cat_od.shtml

So thats one vote against & one for thew exhaust flash.
 

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Discussion Starter · #21 ·
All things can be made to work is my philosophy. This one will just need a little experimentation to find the simplest solution which gives the best result.

Here is my circuit for the rear lights.



Here is the circuit for the front lights in a GT40.

(I suspect the rear lights are similar, perhaps the resistor value is > 1K. If someone can check this in a Mini I will amend accordingly, but we will use this for now)

I hate this Smart Draw cct diagram program, I can't get the lines straight, if anyone knows abetter one let me know.



My circuit is designed to work from 5v the Scalextric one from 12V and of course is only trying to simulate rear lights.

So the possibilities.

1) Just cut and join tracks on the circuit board to recreate my circuit. The value of the 4k7 resistor may need changing dependant on the efficiency of the Led's.

2) My circuit can probably be made to work with parallel Led,s. This may reduce the amount of cutting & joining needed.

A starting point for this approach would be to short out with a small piece of wire the two 1K resistors. Now connect
BK to point A
HL to point B via a 4K7 resistor
Gnd to point C

This will work but depending on the efficiency of the Led's they will probably be too bright. Adjust rear light brightness by changing the value of the 4K7 resistor.
Adjust the brightness of the brake lights by adding a resistor in series with the BK lead.

Hope this makes sense perhaps someone can give it a go and come up with some values.

Richard
 

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Discussion Starter · #22 ·
OK you know me. This is not the easiest option but for me is the most elegant and the way I would go.

Still based on the GT40 front light board. The Mini rear light board is bound to be different can someone post one up?



Here is the original board



Here is a PaintShop modified one.

So we reverse L1 to put it in series with L2
We shuffle R2 across & it becomes The rear light resistor ( needs to be changed to 4k7)

We use R1 as a Brake light adjust resistor, will need reducing in value or a short as in the original design.

P1 becomes the BK connection
HL goes to one end of the moved R2
The LH end of the original R2 becomes Gnd

Of course this may all be useless if the Mini rear light board is very different. I suspect something similar will be possible.
 

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Hi Mike

Thanks for the picture. Just need to confirm where the tracks go,



Can you confirm that the tracks in Red are right.

In particular the connection to the - point.

The tracks in Blue are confusing me can you confirm that they do not connect to the Led's, and that I have got the Led tracks right.

Another Question. Is this a picture of a digital or analog mini? Wonder what happened to R1 & R2?

Richard
 

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Doh...

Ok that makes a lot more sense now, anyway assumptions were correct.


A series diode, then 1K to the Led fed from 12v either means the lights are very bright or very inefficient?

Analog or digi car?

Solutions 1 & 2 still hold. Will go and see if there is an "elegant" one.

Better go & edit my pictures.
 

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Here is the equivilant of the "elegant" mod above, Note **** This has been changed since original post ***

This is not easy when you have not prototyped it first.



So we reverse D2 to put it in series with D1
Remove R4

We use R3 as a Brake light adjust resistor, will need reducing in value or a short as in the original design.

I have used a wire ended resistor for the new R4 as more people have these. Drill hole in board at top to secure lead and solder to HL .

Remove Red & black wires from + & -

+ Becomes the BK connection
HL goes to one end of the new R4
The top end of the original R4 becomes Gnd
- Not used

Please also bear in mind that 4k7 is probably the wrong value, this is a theoretical modification, needs someone to do it and experiment with values.

Since when have Minis been rear engine rear wheel drive?
 

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Discussion Starter · #31 ·
Hi Guys

There are many ways to skin this cat. If the Brake or Rear lights are too bright, just add a resistor in series with the lead that feeds them.


It can probably be made to work with the Led's left in parallel. I would experiment, but have not got a car with the rear light board.

The key is simple get volts to the rear lights & increase it in brake mode.

Glad it works in practice.
 

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Discussion Starter · #33 ·
Hi H

That's good news. I was concerned that without the 1K series resistors that if the the Led's were poorly matched they would each have a different brightness. In practice they probably all come from the same batch and will be fine. Turning one Led round was always going to be a bit tricky so I think this will be the best solution.
 

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Here is something that you might like to try. As long as the Led brightness level is OK or too bright it can be made to work.



Remove the existing + & - wires to the board.

So no mods at all to the board, connect as shown.

If in Rear or Brake mode the Led's are too dim then this will not work. However if they are OK then we are done. If they are too bright in either mode then add a resistor in series with the appropriate lead.

Perhaps someone could try this & report back.
 

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Discussion Starter · #36 ·
No diode needed. It is using D3 on the board.

This method not tried yet so may not work. Problem is if Led's are too dim.

If Brake or rear lights are too bright put a resistor in series with either the HL or BK wire as appropriate.
 

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Discussion Starter · #40 ·
Hi Washout

As a starting point I would wire the Headlamps to the guide connected through a diode and then a single 1K resistor in series with each of the 4 led's.

The Brake lights wire to BK through a diode and the Rear lights to HL through a 4K7

So the front lights are the same as the Scaley GT40 except *4. The Rear & Brake lights are the same as my circuit except separated.

You could wire the Brake lights through a resistor instead of a diode. 470 ohms would be a good starting point.

Then just adjust the values of the resistors to get your desired brightness while not going outside the rating of the Led's or drawing more than 20mA from HL or BK.

Hope this makes sense?

Richard
 

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The current is quite low. For the headlamps I guess < 25mA. But have not seen the spec of the Led's. So almost any diode will do. A 1N4001 would be way over the top but are easy to get. If you are ordering from Rapid, see what they have got at >100mA.

I am using BAW62 because I have a load of them. 1N4148 also OK Both of these rated at 150mA

As I say most will be OK
 
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