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O.K, I know we have discussed this before but I have never seen a list of required components to assemble a light bridge or the recieving led or a wiring diagramn for the computer leed. Help me out, guys, and give me a list of components to get from Dickies so I can setup a timing system. Particularly a system that won't need a light bridge if it exists.

 

Ta


Stu

 

Old racers race harder

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follow the link stu. Ive built and tested this circuit and it works. Its bullet proof. If you use background lighting you are always going to run the risk of miss-timing. Your call however. To get rid of the light bridge use the dick smith photo transistor as it response curve goes way into the visible light and not just UV. personally I think this is dangerous and will lead to miss-timing.

 

I cant comment about how well any other circuit may work but the one I designed works a treat.

 

http://www.auslot.com/forums/index.php?sho...20&start=20

 

cheers

rick1776


cheers

rick1776

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Theres a IR led and reciever you can buy from jaycar.

 

ZD1901

 

productLarge_3109.jpg

 

I used one for my hill climb. It fit nicely into the slot. no light-bridge required.

 

as for the wiring I set it up to the joystick port as per http://www.hoslotcarracing.com/

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I have no doubt Rick's circuit is a pearler, but it may be beyond a lot of people's ability to build it.

 

I personally see no need to go beyond the basics of

1) an LED of suitable wavelength emission directly above the track with a resistor in the line of each LED of suitable value so it doesn't think it has unlimited power to suck up and go POOOOOOOF. This being above

 

2) A sensor/photo-transistor/photo-interruptor/thingummyjig what runs off and looks for light roughly f the type what the LED is emitting, and gets all excited and goes yeah baby, or get lost dude depending on if it gets enough; which is wired to some pins on the parallel port of a computer.

 

There may be exceptions as parallel ports have a bit of fluctuation in performance, but that is a tiny minority, so I reckon it's worth doing it the simple way first before embarking on an electronics build process that is outside your comfort zone and create more difficulty for you.

 

There are several threads on forum which give diagrams, resistor values etc, I've posted these at least twice in the last 6 months, so I'd encourage you to do a search, you may turn up all manner of other interesting things.

 

Alternately you can do what Johnno suggested, where the LED is on one side of the slot and the sensor is on the other side, all in the same device. [wiring is the same, it's just the physical arrangement of LED and sensor that is different].

I know a club and related bunch of home race members who always/only use that system.

 

My caution having used it myself, is that the "line of sight" between the emitter and sensor is 2 -3 mm below track surface and when I mounted mine 1.2 metres into a straight, I found my higher torque and better gripping cars would actually lift part way out of the slot under acceleration, and the guide would sometimes fail to break the beam. Alternately, putting it mid straight meant that at any speed greater than 13-14 feet a second [from memory -I forget the math and probability calculations], the sensor might "miss" the break of the beam by the slot guide, and fail to register a lap, depending upon how often the sensor "looks down the circuit" . At 5 or 10ms samplings for older computers, it missed laps regularly, at 1ms samplings, it wasn't too bad, but was certainly nothing like bullet proof.


Recovering Slot Addict :ph34r:  *  Custodian of many used screws (mostly loose :rolleyes:)  *  Total kidder  *  Companion of other delusional slot addicts :lol:  

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Thanks guys.

 

Rick, how big is the bread board you used and did you mount it in a box or just screw it to the bottom of the track?

 

SlotsNZ, I got a piece of paper on the wall that SAYS I've got a bigger comfort zone than the average Fred so blowing things up doesn't worry me. I blew up a few things at tech including a couple of batteries just for the hell of it. :angry:


Stu

 

Old racers race harder

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Thanks guys.

 

SlotsNZ, I got a piece of paper on the wall that SAYS I've got a bigger comfort zone than the average Fred so blowing things up doesn't worry me. I blew up a few things at tech including a couple of batteries just for the hell of it. :P

 

hee hee, if it's that big, can I park up there I while, I run out of mine just wandering from the computer to the coffee machine :angry:

 

Glad you took me the right way, I was partly writing specifically for your situaiton, and partly for the other joe-slot-citizens that might read the thread and ponder their timing options.

 

Likewise for you Rick - not knocking what you do either, just postulating . . . . . or some word like that . . . . another common option.


Recovering Slot Addict :ph34r:  *  Custodian of many used screws (mostly loose :rolleyes:)  *  Total kidder  *  Companion of other delusional slot addicts :lol:  

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Time to play spot the novice.

 

How do you display the output of the timing systems? Do they need to be hooked up to a PC?

 

N

Edited by Nick

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Time to play spot the novice.

 

How do you display the output of the timing systems? Do they need to be hooked up to a PC?

 

N

 

 

Simple answer, yes. Don't worry about being a novice though, Nick. We ALL were at some time in the distant past, a bit more distant for some than others. :rolleyes:


Stu

 

Old racers race harder

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I used reed switches on my HO track - not sure if they'll work for 1/32nd, but at about $1.50 a piece they are cheap enough to experiment. I used these as I wasn't keen on a light bridge either and my track needs to lay flat against a wall when in the 'non racing' position. Otherwise the photo-interrupters as mentioned above, but I found them to be cheaper at Altronics - about $2 compared to the Jaycar $5.50 or so.

 

Look at the HO website mentioned above, it gives the wiring diagram for older type computers (ie COM1 and Printer ports, rather than USB) and the author of that site has also produced a piece of software called Laptimer 2000 which is what I use. Again, this is for HO so your milage may vary.

 

Hope that helps!

 

Richard

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Richard, the reed switch idea did cross my mind but I'm running non-mag so nothing to activate it.


Stu

 

Old racers race harder

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Theres a IR led and reciever you can buy from jaycar.

 

ZD1901

 

productLarge_3109.jpg

 

I used one for my hill climb. It fit nicely into the slot. no light-bridge required.

 

as for the wiring I set it up to the joystick port as per http://www.hoslotcarracing.com/

 

We actually use these on the Phillip Island Raceway and they have never missed a beat. They are in the middle of the 13 mtere straight so cars are travelling at top speed when they cross. Average lap speed in real terms is 15 kph so I'd say they cars were croissing the sensor at 25kph - and a theoretical max speed of 35kph. The only misscounts have come when Joe Public have buggered up the guide braids lifting the whole from end of the car.

 

The trick is to get the voltage correct. We run them at 1.25v REGULATED. It must be regulated else forget it.

The big bonus with using these is that because the PI track is so big and more importantly its very spread out we were looking at having a long cable run from the sensors to the PC which is not ideal. After testing we ended up with a huge run of 35 metres from the startline to the PC. Amazingly everything works without a beat. If we had used the ordinary in slot sensors we would have been very much restricted in terms of cable length - maybe 5 metres max but even then its not recommended.

They are a pain in the arse to fit though compaired to just drilling a hole and slipping an LED shaped sensor in

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Stu,

 

The cct should fit onto a 2" X 2" bread board. I used one of those plastic test bread boards and layed the cct out approx 1" wide by 3" long to test it. Two guys in out club wanted a more robust timing system. I dont think they built the cct in the end but thats another story.

 

The IC has enough op amps on it so that each IC can do 2 lanes. However the wiring gets a little bit more complicated. If you want to keep it simple just use one IC for each lane and build 4 seperate ccts. The IC is only about $1.50 so cost shouldnt be an issue.

 

You can use the photo interuptor as suggested by aastes but I would suggest that you then definitely must use my cct as it has a pulse stretcher built into the device. Using the interuptor the only thing setting it off would be the guide flag. If the flag is only 20mm long and your car is doing 6m/s top speed then the amount of time the flag is in the way of the photo interuptor is 3 milliseconds, 0.003 seconds. If the port is not being updated faster than every 3ms then you will miss laps. My cct has a pulse stretcher that takes this out to half a second. Even the slowest PC will update the port faster than this.

 

I know the cct looks complicated but if you lay the components out as per the drawing and then use hook up wire it shouldnt be that hard. I know that there are lots of easier ccts out there and some people connect the IR receiver directly to the port. However depending on the port etc the output of the IR receiver may be "loaded down" to the point where it may not trigger reliably. So you have one guy saying it works fine and then another guy saying he cant get it to work at all.

 

cheers

rick1776


cheers

rick1776

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That is excellent news Rick. Probably won't need to stretch the pulse as it is going in to a single lane rally track. Will only need the one IC as well. This will be in the door track I built (update pending) so there are no long straights. Longest straight is 6'3" and that is along the full length of the door. No hope of excess speed :)


Stu

 

Old racers race harder

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