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Nobby Berkshire
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Sorry for what seems like an innocent question. I'd search the other threads for an answer, but too many of them are so full of non-information, chest-beating, and self-opinionated stances about digital, that I can't be bothered to plod through them all!!!


Can anyone explain to me how digital laptimers work. With all the cars on one lane when the cars cross the counter, how does each one get registered and recorded separately. Or, is it the case that you have to get back in your own lane before you cross the line at the end of each lap?

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...encoded guide-flags like Carrera does - counting the interrruption of a light-barreer - or small transponders like the 1:10-RC-cars use. No big deal but 2 of 3 manufacturers still have not sorted out how a TIMING-system works....
 

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Hi Thomas,

QUOTE No big deal but 2 of 3 manufacturers still have not sorted out how a TIMING-system works....

Carrera has a timing-system, this means that SCX and Scalextric do not have a timing-system on their digital track
....so what the hell are they doing ????

Greetings from Zürich
Zubi
 

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Hi,

In Scalextric system cars has leds (photodiodes) in their chassis. Every led sends different frequency so thats how lapcounter is able to register every car separately.

I don't know that how SCX works.

Optional way is to replace leds with ultrasound sources (every car has own frequency). In that case lapcounter is able to separate cars from their sound.
(used allready in many other applications)

There is also more different methods for lapcounting without "barcodes" but those are cheapest.

Best regards:

Sami
 

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I had a look at how SCX does lapcounting.
There is a magnet under the start track and a reed contact on the decoder board in the car. The lane counter track itself can be connected at any place of the layout. It is receiving the counting signal together with the car ID through the track. Without having had a look at the signalling itself yet, this configuration seems to be quite different to DCC and looks more like a one-wire field bus technology with actors and sensors. DCC to my understanding has been a one-way protocol with loco decoders only receiving commands, whereas the SCX 'decoder' at least can send a counting signal to the counter device.
 

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Beppe Giannini
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Sami,

if I understand correctly what Nep72 told me, Scaley's LED has a dual function :
- it "blinks" all the time with the car's ID - which is actually picked up only on the start line - but then what's its life expectancy, or would the blinking be initiated by a magnet ?
- it "glows" when you push the lane change button - this (un-differentiated) signal is picked up by the sensor before each LC - but would this interfere with lap counting if you pass the start line with the lane change button pressed ?

Joerg,

congratulations for being the first (including Spain) to throw some light on SCX's lap counting - all we knew so far was that the car's ID was indeed picked up by the control unit, and the signal then sent to the lap timer tower via the rails (hey, I even know what a field bus is !)
We did not know about the magnet - now, it remains to be seen how the car sends its ID to the control unit, and this would be quite significant because it could be an application of that 3rd generation DCC technology Julius is (I believe rightly) counting upon for the "Standard"

Ciao
Beppe
 

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More questions about Scaley Digital.

Thinking how lap detector could work here, and based on the LED as emitter, I can't imagine the detector: car is travelling, LED emits a code, say it takes 23 milliseconds. In that time, car is 15 centimeters farther -remember these numbers, Beppe?- So, is the detector a 20cm row of detectors or something similar? I need more info here, I've not "seen the light".
 

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As we currently do not have any reliable information from the source, it is all assumptions. If I may add one more: the technically cleanest way would be RFID technology. A manufacturer would use that if he was keen on having a superior product which works independently from the track system used. But the costs for RFID transceivers still are significant, it would make time measurement pretty expensive, probably too expensive for a mass market.
The second possibility is what SCX are doing: The car-decoder is not sending out a signal, but it is receiving it and then forwards it together with it´s ID to the lapcounter device. This is significantly cheaper and my guess is that Scalextric are doing it the same way, maybe using light instead of magnetic impulses.
 

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Led technology is widely used in remotecontrols etc...

All frequences means different thing. As we know, blue light has differend frequency than green and red. It is same with IR frequences. It is not new invention and it is easy way to control and reconize things. Since scalex is using leds it is quite obious what they'll do with it.

Quite interesting info of SCX system.
 

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DT
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QUOTE (joergresch @ 1 Sep 2004, 10:47)As we currently do not have any reliable information from the source,...
Here it is:

QUOTE (From the source)Digital lap timers: The module in the cars has a small led that transmits a continuous pulse through an aperture in the bottom of the car. The pulse is unique to that car and is programmed in when you assign a car to a particular hand controller. In each lane of the start line half straight there are two sets of optical sensor, each 45mm in from the end of the track. The first sensor (on the right as you face the display on the hardware) is an optical sensor that picks up the pulse identifying the car. On the left (and on the start line itself) there is an LED/sensor combination throwing a beam across the inside of the slot (pretty standard stuff). The lap time is recorded when the guide blade breaks the beam. The trick is that the trackside hardware will register the lap time for a car whether it breaks the beam first and then gets a pulse from the car (i.e. car travelling left to right), or gets the pulse from the car and then breaks the beam (car travelling right to left).
 

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Beppe Giannini
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OK Nuro,

since you have Friends in High Places, can you get them to explain how the same LED triggers the LC ?

From this picture on SCI, it would appear that the half straight before the LC has four sensor locations too (althouh I doubt all would be used, maybe it's just to use the same mould)

http://p075.ezboard.com/fpockitfrm27.showM...opicID=61.topic

Oh, while you are at it, could you also ask if the LC blade is elecrically live, and if only the ingress blade moves (the exit one being fixed), and.........
 

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DT
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When I saw the demo of the prototype the LC blade was not live and the car stopped on that spot a few times. I pointed out to Adrian that it would be better to make it live and with a few electrical bits and pieces, you could change it's polarity as it changed position.

I'll ask about the rest.
 

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Beppe Giannini
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Thanks Brent,

quite informative - at least for us general populace

Yes, I can see digital becoming a sensor nut's paradise !


Ciao
Beppe
 

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A question, Carrera has a digital system that reads the cars guide flag?
This is exactly what I was thinking about and I think it would be the most versatile. I like the idea of changing a cars guide flag and getting a new ID for that car. It would be nice if you could just insert a small strip of encoded metal into an existing guide, like a strip of metal with a bar code on it.
I think the bulk of the decoding hardware should be somewhere else but in the car! I have 50 cars and if I want to bring them all up to digital readiness it might be cost prohibitive to say the least.
 

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Hi MrBug,
Carrera has 2 different ways of identifying a car. One is for communication between controller and car. This is done through a dip switch on the bottom of the car. The other identification is done through holes in the extra-long guide. This one is for measuring the time and counting the laps of a car. Either of these 2 identification system is for a maximum of 4 cars. This number can not be extended. It is not possible to use barcodes instead of a hole in the guide. Cars travel too fast to read a barcode. Carrera does not offer a possibility to upgrade your existing cars. The only way to get a Carrera car decoder is to buy a PRO-X car.
Best
Joerg
 

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Humor me for a second.
Everyone told me cars traveled to fast to make a reliable lap timing sensor system based off the guide flag but I did it. I watch the check out girls at the food store chuck the items across the laser and unless the item's bar code is on an angle it reads it no problem. Has anyone tried to read a simple bar code off the guide flag? The complexity of the bar code does not need to be 10 digits long in fact 2 digits would be fine and even 1 might work.
I'm just thinking here, I know bar code reading software has matured to the point where it is almost freeware or at least I'm sure I could find the source somewhere on the net. If the lap timing could be a separate identity to the car's controller would this not reduce the complexity of the controller?
 

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Hi MrBug,
you should try it, because it would be great and it would be cheap.
But I don´t think that you would manage to get something to work, because good scanners (the ones which cost 2000$) make
2000 Scans/sec with a min. resolution of 0.191 mm. So, this would count to a maximum speed of 38.2 cm/sec. An average slotcar makes about 25 km/h, which is 6.94 m/sec, 20 times more than that good scanner would read. Reducing the barcode would mean that you have to leave a standard and re-invent the wheel.
Best
Joerg
 

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Beppe Giannini
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Joerg,

I don't want to get into this for a moment - although I had the same thought as Brent, you only need to read a number from 1 to 6 and maybe you could get away with a largish sticker on the car's belly

I believe the real issue is :
QUOTE I think the bulk of the decoding hardware should be somewhere else but in the car

Well, the only alternative would be finding real smart mice (possibly from Kerpen)


Ciao
Beppe
 

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Julius Wilkko
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Hi all!

Interesting conversation. I have come to conclusion that you need a combination of technologies to provide accurate 1/100 timing in digital slotcar systems.

I will try to use RFID type of technology for identifying each car. Each car will have a RF transmitter that is not trying to send any data, just car-specific frequency. It´s just like Scalex system but the LED is replaced by RF. As supporting technology I plan to use IR-gate at the track. These sensors will provide accurate timing.

How lap-timing is actually done?
When a car is approaching starting line, an antenna below the track surface detects that the car (ID1-16) is approaching. It relays the information about this to the timing processor at the command station or to a PC. Command station will now start listening starting line sensors that will provide accurate timing. These sensors can be LDR, IR, Laser, whatever. When the car is detected by these sensors, timing processor/PC sees this and combines the car ID(car1-16) with the accurate timing information from the sensors.

All this is just theoretical. I haven´t tested anything yet. This way it could be possible to achieve 1/100 or maybe even 1/1000 accurate timing in digital systems.

Julius
 
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