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Hi guys.

Getting a bid tired of unreliable lap counters and was looking for a way to build my own. Any clear articles on building either a light bridge or some other reliable type of lap counter hardware would be appreciated.

I'm not to worried about the software side as i will probably write my own.

Cheers

Was
 

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Julius Wilkko
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Hi!

Note that Gregorys hardware is for HO scale where you can place LED emitter and sensors very close with each other. In my opinion this cirquit will be very hard to get working 100% reliably in 1:32 scale where the emitter to sensor distance is greater. You can try to replace the LEDs with cheap lasers and use fast photodiodes as sensors. I have provided circuit diagrams here once before. Try n ´search, maybe you find them.

Cheers!

Julius
 

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Mampara , I am using Infra Red LED,s mounted 3" above the track .
They are giving the odd missed hit , this problem i think is caused by using the same power supply as the track ( car draws more power/light dim,s ) . I intend to get a dedicated 12V supply just for the LED,s .

Richard
 

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Brian Ferguson
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I use simple Radio Shack items, high-power (100ma) IR LEDs in a bridge 2.75" off the track surface, and matching RS photo-transistors pushed up from underneath and "looking" through the bottom of the slot at just below slot depth. I drive the LEDs with a separate supply at 6V through a 68 ohm resistor to drive them at a very safe level of around 88 ma. In tests at 100ma, the system worked fine at 3".

In several years, I have yet to experience a missed count or a failure of any component.

For my next track, I plan to use some higher power (200ma) IR LEDs and matched photo-transistors that offer increased sensitivity at more precise beam angles, something that is relatively easy to account for in a bridge-based system. I expect to get proper results with a gap as large as 4 to 4.5" between LED and sensor.

Personally, I think optical is the easiest way to go. The only requirements are that the units (LEDs and photo-transistors) must be "matched", that is, the LED emits at a spectral frequency that is very close to the optimum frequency for the photo-transistor, and that the IR LED is a high-power item (100ma or more). Oh, and yes, a separate power supply for the IR LEDs is an absolute must - clean power = clean light.
 

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QUOTE (Fergy @ 16 Dec 2004, 05:10)I use simple Radio Shack items, high-power (100ma) IR LEDs in a bridge 2.75" off the track surface, and matching RS photo-transistors pushed up from underneath and "looking" through the bottom of the slot at just below slot depth. I drive the LEDs with a separate supply at 6V through a 68 ohm resistor to drive them at a very safe level of around 88 ma. In tests at 100ma, the system worked fine at 3".

In several years, I have yet to experience a missed count or a failure of any component.

For my next track, I plan to use some higher power (200ma) IR LEDs and matched photo-transistors that offer increased sensitivity at more precise beam angles, something that is relatively easy to account for in a bridge-based system. I expect to get proper results with a gap as large as 4 to 4.5" between LED and sensor.

Personally, I think optical is the easiest way to go. The only requirements are that the units (LEDs and photo-transistors) must be "matched", that is, the LED emits at a spectral frequency that is very close to the optimum frequency for the photo-transistor, and that the IR LED is a high-power item (100ma or more). Oh, and yes, a separate power supply for the IR LEDs is an absolute must - clean power = clean light.
<{POST_SNAPBACK}>
Can you show a wiring diagram? Thanks.
 

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Another question on this subject. Which pc port do you guys use? In Gregory's software it says that it uses everything from the game port to the printer port. I want to use the COM port seeing thet I've got a printer attached. But it still doesn't work.
 

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Why do you want to use a lightbridge? It is easier ( and more reliable) to use a "optic sensor" like the CNY 37. The distance between the transmitter and the receiver is 3 mm. I use them in mine woodtrack. They cost around €1,50.



I use four sensors. Two for both lanes and two for the pit. The SN7402 is a XOR IC and gives a signal to the computer when a car passes through the pit or crossing the start/finish line.



The rest of the print is based on hardware found on the following site:

T.U.R.M - The Ultimate Race Manager

And I was also inspired by the next site:

http://www.carrera4fun.de/
 

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Although I have a 'homebuilt' mdf track, I bought the 4lane DS system from Pendleslotracing and used 'dead strips' for about a year. Then looked on ebay UK and found a DS 4lane light bridge, had to construct a new piece of track with the correct 'Scalextric/SCX' lane spacing, works faultlessy with the counters. I believe that if you have a PC to spare, software has already been written, the name 'Criccrac' (or something similar, saw it on slotcarcademy pages, - just google it) comes to mind, just might save you you a lot of time. Hope this helps. ( PS, beware if night racing, there is a distinctly 'pink' glow emanating from the light sources)
 
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