[SinclairZX81]

For those racing against the machine by taping a controller trigger, here's a neat twist to make a perfect mimic car.

Normally a 'tape-ghost' car will never change lanes because it will signal to an upcoming LC section to flip to the don't change position, which makes for a rather boring racing partner who sticks obstinately to whichever lane he started on...

...unless you disable the signal LED (a piece of black electrical tape over the LED will have the desired effect.) I discovered this because the LED in one of my Boxers blew up. The car still drives, but it can't change lanes - or to be precise - it can't signal the LC flipper to move either way. What this means is that it will simply take whatever line the preceding car took. So if I change lanes at LC 1, ghostie changes lanes at LC 1 and if I didn't change lanes at LC 2, neither does ghostie! He perfectly mimics whatever I do lap after lap!

I managed to set ghostie up at a fast enough speed that he was fishtailing some of the corners and challenged him to a 20min endurance race. My Skoda is less 'stuck down' than the Boxster and while I was faster he was ruthlessy consistent. I'm glad to say I won, but it was a lot of fun and we collided more than a few times!

 

[martinkay]

Great idea, I will try that today. Previously I had been taping over the lane change button to get the tape-ghost car to change lanes (but then of course it does it every time).
Cheers
Martin

 

[SWoRd]

Hi Sinclair

Thank's for the tip with taping the LED.

QUOTE (SinclairZX81 @ 10 Jan 2005, 09:03)For those racing against the machine by taping a controller trigger, here's a neat twist to make a perfect mimic car.It's also possible to make a more permanent ghost car controller using a 2,5mm minijack and a 4,7Kohm potmeter ... it's a bit easier to adjust the speed accurately that way.

 

[astro]

Great idea, can't wait for my set to arrive!

To the electronic geniuses - presumably the socket sends a control voltage through the controller to be able to work out the resistance provided by the controller/pot.

Could this be used to power a simple flipper circuit or flashing led type thing, so that the dummy controller would give randomly (or just every 1/4 second alternately) the button pressed and button not pressed data to the base?

I am pretty sure it could be done - maybe requiring battery power. I just don't have the expertise to either do it or know how complex it would be to do.

 

[Skeeter]

i wonder if presure would promote scalextric to make something like this. just have a small device that clips in with a throttle controll and randomly presses the LC??

 

[martinkay]

I tried this today - must have done something wrong - taping the underside of the car means it doesn't register its car ID when passing the powerbase, so doesn't figure in race times or positions...

 

[SWoRd]

QUOTE (Skeeter @ 10 Jan 2005, 14:11)i wonder if presure would promote scalextric to make something like this. just have a small device that clips in with a throttle controll and randomly presses the LC??That should not be too difficult. All you need to do is add 8,2Kohm in series with the potmeter from time to time.

You can do this by supplying the resistors with a random LC signal through a N-channel FET transistor that will occationally short the 8,2Kohm lane change resistor.

Here's a small diagram.

 

[astro]

nice - the change signal does not have to be random. If it is a regular 0.2ish second alternating signal, it will be pretty random which LCs it changes on and which it does not

 

[SinclairZX81]

QUOTE (martinkay @ 10 Jan 2005, 20:49)I tried this today - must have done something wrong - taping the underside of the car means it doesn't register its car ID when passing the powerbase, so doesn't figure in race times or positions...

<{POST_SNAPBACK}>

Of course! I guess I was having so much fun I didn't even notice! Oh well, if you're not bothered about who actually won etc., its still fun!

 

[SinclairZX81]

QUOTE (SWoRd @ 10 Jan 2005, 21:10)QUOTE (Skeeter @ 10 Jan 2005, 14:11)i wonder if presure would promote scalextric to make something like this. just have a small device that clips in with a throttle controll and randomly presses the LC??That should not be too difficult. All you need to do is add 8,2Kohm in series with the potmeter from time to time.

You can do this by supplying the resistors with a random LC signal through a N-channel FET transistor that will occationally short the 8,2Kohm lane change resistor.

Here's a small diagram.

<{POST_SNAPBACK}>


Sweet! Ummm... any chance you could post a full circuit diag with the pot too? WOuld I need to sacrifice a controller to build such a little black box?

I am pretty sure that Scalextric have digital challenger software on their to-do list, but who knows how long it will be before it happens.

 

[SWoRd]

Hi Sinclair
QUOTE (SinclairZX81 @ 10 Jan 2005, 21:51)any chance you could post a full circuit diag with the pot too?The pot is there ... it's the 4,7Kohm resistor with the arrow going through.

 

[SinclairZX81]

QUOTE (SWoRd @ 10 Jan 2005, 23:02)Hi Sinclair
QUOTE (SinclairZX81 @ 10 Jan 2005, 21:51)any chance you could post a full circuit diag with the pot too?The pot is there ... it's the 4,7Kohm resistor with the arrow going through.
<{POST_SNAPBACK}>


Doh!

OK, I understand the circuit, current comes in through the pot and then either runs through the 8.2Kohm resistor if the FET gate is open or through the FET if it is closed, right? Because current always flows throught the line of least resistance

So one little circle is + and one -, right? They go to the post and shroud (or whatever) of the minijack.

I don't understand the line coming out that is labelled LC signal... Is that just a label?

Do you have part numbers that are suitable to build this thing?

 

[SWoRd]

QUOTE (SinclairZX81 @ 11 Jan 2005, 00:55)OK, I understand the circuit, current comes in through the pot and then either runs through the 8.2Kohm resistor if the FET gate is open or through the FET if it is closed, right?Exactly.

QUOTE Because current always flows throught the line of least resistance

So one little circle is + and one -, right?Yes.

QUOTE They go to the post and shroud (or whatever) of the minijack.Yes.

QUOTE I don't understand the line coming out that is labelled LC signal... Is that just a label?Thats where you connect the circuit that you want to control the lane change.

If you want the lane change to be activated, you must put 0V on the "LC signal". This will turn off the FET and thereby insert the 8,2Kohm resistor.

If you apply 5V to the FET (and you have chosen a logic level FET), the FET will go on, shorting the 8,2Kohm resistor and leaving only the potmeter resistance between the minijack tip and sleve connections. Hence the lane change will be deactivated.
QUOTE Do you have part numbers that are suitable to build this thing?

I haven't been looking into that, but any logic level N-channel FET should do. It will draw less than 1mA, so you don't need a power FET.

You can also use a small NPN transistor (like BC547) if you prefer. Using two transistors two capacitors and four resistors, you could build a multivibrator to control the lane changes with a pseudo random signal.

 

[Skeeter]

QUOTE (SinclairZX81 @ 10 Jan 2005, 20:51)I am pretty sure that Scalextric have digital challenger software on their to-do list, but who knows how long it will be before it happens.
<{POST_SNAPBACK}>

surely if the challenger could learn both lanes, and be able to tell when its changed lane, thats all it would need? and of course it would randomly change lane. this would make a more competitive car to race against rather than one with a fixed throttle (also, if u have a fixed throttle, surely the car will pick up speed on a long straight, and it u have a hairpin at the end, not attampt to slow down) <-- a challenger would!

 

[SinclairZX81]

QUOTE (Skeeter @ 11 Jan 2005, 01:26)QUOTE (SinclairZX81 @ 10 Jan 2005, 20:51)I am pretty sure that Scalextric have digital challenger software on their to-do list, but who knows how long it will be before it happens.
<{POST_SNAPBACK}>

surely if the challenger could learn both lanes, and be able to tell when its changed lane, thats all it would need? and of course it would randomly change lane. this would make a more competitive car to race against rather than one with a fixed throttle (also, if u have a fixed throttle, surely the car will pick up speed on a long straight, and it u have a hairpin at the end, not attampt to slow down) <-- a challenger would!
<{POST_SNAPBACK}>


Yeah. But what I meant was no separate special challenger car should now be neccesary. Any car coul be set to be a challenger. All the stuff the current Challenger ca r does using its internal firmware would now be handled by the Digital Power Base software/firmware/whatever.

 

[SinclairZX81]

QUOTE (SWoRd @ 11 Jan 2005, 01:12)QUOTE I don't understand the line coming out that is labelled LC signal... Is that just a label?Thats where you connect the circuit that you want to control the lane change.

If you want the lane change to be activated, you must put 0V on the "LC signal". This will turn off the FET and thereby insert the 8,2Kohm resistor.

If you apply 5V to the FET (and you have chosen a logic level FET), the FET will go on, shorting the 8,2Kohm resistor and leaving only the potmeter resistance between the minijack tip and sleve connections. Hence the lane change will be deactivated.
<{POST_SNAPBACK}>


Now you lost me again. I thought this diagram was all I needed. Now you are saying I have to connect some other stuff to the FET and LC lines?

My apologies, I am a designer not an electronics engineer!

 

[bmacminn]

I taped the underside of my car. The car stil registered time and it did follow when I changed lanes (although I did not understand why at the time

)

I also noticed the car that I taped would register as car #1 (i had it set as two) from time to time.

If I wanted to have two cars on 1 control and I only wanted 1 car to score, could I just start 1 of the cars before the start finish line?

brian

 

[astro]

my guess of the lap counting method is: the led says which car, the guide flag (scalextric say it is important the guide is black for lap counting to work properly) says WHEN the car crosses the line;

My understanding of what is happening is that the base sees the main untaped car's led and goesok, thats LED #1. Then that cars guide passes the sensor, and it goes 'right, a lap for car #1.

When the untaped car passes the led sensor, nothing happens. When the guide flag crosses the guide sensor the base goes 'errrrm, ok someone has done a lap, the last LED i know about is car #1. Must be another lap for #1'

You could test this theory if you have a spare black or blue guide. after the car #1 has done a lap, dust slide it along the slot and see if another lap is counted for the same car. I am still awaiting my dogotal, so cannot test for you yet.

If this is the case, you need a white or clear plastic guide