Adding Rear & Brake lights to digital cars

RichG · Jun 17, 2005

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.....

Ian B · Jun 17, 2005

Rich,
Great article is there anything that you would not contemplate taking to bits? Bet you were just like this as a child with the radiogram or record player! Still I can't wait to follow this atrticle to the end

.

Cheers
Ian B

RichG · Jun 17, 2005

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.

RichG · Jun 17, 2005

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.

RichG · Jun 17, 2005

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

astro · Jun 17, 2005

Fantastic! The GT40s always missed having working lights at all, its great to see it with working brake lights!

On the GT40 in the xbox game Forza, the top and bottom lights seem to be wired together so they both come on together... but I am not sure whether this is correct or not.

Maltese · Jun 17, 2005

Excellent, RichG!

Has no one else seen this on the chip? Were there Scaley instructions on hooking up the brake and headlights? Why would that not have been published?

You are awesome, RichG. Do you have an inside Scaley line or are you just figuring this stuff out as you go along?

Do the tail lights flicker when you go over the switch track/finish line?

-Maltese

RichG · Jun 17, 2005

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.

drummer · Jun 17, 2005

Totally wicked! Ive said it before -- You da man!
I can't wait to do this! Im off to the shelf to see how many of my cars are suitable.

I guess we should all be thankful to Scalextric for the foresight.
woohoo!

tvwino · Jun 17, 2005

Rich,
you've done it again - I wish I had a dollar for every time I looked at the early saloon boards and wondered what all the unused pads were for...

well, now we know!!

Awesome - will have to take a look at my shelf now too.

SinclairZX81 · Jun 18, 2005

Damn you Richard! Now I am going to have to wire all my cars like this!

Couple of questions (as always):

1) What about headlights?

2) What happens when you run the car on analog?

RichG · Jun 18, 2005

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.

tvwino · Jun 18, 2005

QUOTE (RichG @ 18 Jun 2005, 18:40)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.
<{POST_SNAPBACK}>

Rich,
I'm definately going to play with this, although had planned using the F1 chip, but will revert to the saloon chip now to make this happen (couldn't see anything on the F1 chip during a brief look in one of my recent conversions).

OK, as for the yellow exhaust flames... well, we all have off days sometimes don't we, even you it seems

Yes, it would be an LED too far!

Overdrive make those yellow flame options, can be added to some of their light board kits... but never has it even been close to something i've thought worthwhile.

Cheers - keep up the good stuff, and no more dumb ideas please, you've had yours now for 2005!!

Mike

RichG · Jun 18, 2005

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

drummer · Jun 18, 2005

Morning bleading edgers, Rich, dont know if you have a Scalextric mini, but wonder whether we could attach the rear light circuit board via same method?

RichG · Jun 19, 2005

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?

hiredassassin · Jun 20, 2005

Rich, brilliant work AGAIN!!

I will certainly be attempting this with some of my cars - eventually

i just had a few questions:

1. if you hook up headlights/taillights using the digital board points, do they stay on all the time, or do they increase in brightness with the throttle? (i have only done 1 conversion so far, and i hooked up the headlights directly to the guide terminals)

2. in the above method of attaching headlights (direct to guide), the lights are only dim (im guessing this is beacause the power form the rails is ac not dc, so the led (being polarized) is actually flashing really quickly at the same frequency as the ac power - only on half the time), can you see a way of getting past this and making the headlights brighter? If not can you devise a circuit for attaching headlights to the digital board that stay on all the time?? (i only ask this cos you seem like a man who needs a mission! )

also, i dont know if you know or not... leds can be shaped and filed down to size or different shapes to suit different cars if you need. You just need to finish off with a very fine sandpaper or file and then give it a coat of clear - as long as you dont hurt the metal contacts within. I used to do this for my model trains..

and... i reckon the exhaust flash is a great idea!

RichG · Jun 20, 2005

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.

beach cruiser · Jun 22, 2005

Thanks very much for the information and work shared. As the knowledge spreads, more people benefit, probably more than you might have have considered. I don't see a lot of people who have much experience with this feature, so they do not know if they would like it or not.

Working brake lights did it for me. Scalextric style lights were ok , but did not offer a big advance in realism, whereas a working brake light advances the little miniature car effect.

Lights are such a great feature, and as knowledge grows, so will demand in the market place. I have often seen buying decisions reached because of the car being lighted. Not just me, although that is often the case, but little kids and the wives buying to please little kids and husbands.

I'm planning to implement the knowledge you have shared. I would have had no chance to improve my cars in this way without this post, being limited to off the shelf parts and a slight understanding of what's going on with the parts.

I would like to try and repay in kind, if possible. Connectors to ease body removal are hard to find for a reasonable price, in my experience. Hobby shops have miniature plugs for trains, but at a cost almost or equal to a large part of the entire lighting project.

I stumbled across inexpensive miniature plugs sold as computer parts for power supplies to fans and stuff on the boards. Some are a little bigger than a modeler's optimum choice for size, but acceptable, and the price is in line with normal parts. They come prewired as a jumper cable, so the plugs are already connected on each side. Angle cut the wires as needed, and you have in hand a male and female plug with factory attached leads, ready to install. Even the the colors of the wires match those in most cars, and look very much like some plugs used on Fly circuit boards.

hiredassassin · Jun 22, 2005

QUOTE (RichG @ 19 Jun 2005, 18:39)Don't quite understand the question, there is no rear light circuit board as such, just a couple of components and the Led's?

if the min's rear lights are same as the 307, they are mounted on a pcb, with an inline resistor and diode for each led. dont know the values.

Do you think this set up would still work, taking into account these extra components?

ill be trying on the weekend...

RichG · Jun 23, 2005

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

RichG · Jun 23, 2005

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.

tvwino · Jun 23, 2005

QUOTE (RichG @ 23 Jun 2005, 21:12)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?

Rich,
as requested, here is a pic of the mini rear light board - hope the clarity is OK.

Cheers, following this thread with interest.

Mike

I edited the picture to shrink it 'tvwino'. Please can you keep your pictures to 600 pixels wide so the rest of use don't need multiple linked monitors to see the picture? thanks!

RichG · Jun 23, 2005

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

tvwino · Jun 23, 2005

QUOTE (RichG @ 23 Jun 2005, 22:01)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.

Richard
<{POST_SNAPBACK}>

Rich,
your assumptions on the track layout are spot on - although the reason you were confused and have outlined the blue tracks is that the light patches are actually the board, the dark patches are the tracks. So to answer your question, the blue doesn't go anywhere - your red tracks are spot on.
...and the resistors are 1K

N.B. side note to swissracer, and everyone who doesn't have a 50 inch widescreen monitor on their desk - sorry for the size of my picture, didn't think about pixels - just focused on getting it reduced to below 1MB from it's original size.

RichG · Jun 23, 2005

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.

Adding Rear & Brake lights to digital cars

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