Drag race Christmas tree

Dunno.

If it's just light 1 then light 2 then light 3 then light 4 etc.. Guessing under $10.00 in control electronics. Lamps or power LED's will add to cost. A microcontroller can be programmer or perhaps use ye old 4017.

• a generic timer chip (555).

Dunno. I make electronic stuff. I don't shop for it. A programmer could write up some code for a laptop to signal the lamp switching electronics.

Some do come with everything, but all integrate with the system so that there is coordination between timing and start.

Check Jegs, or one of the other automotive (custom/racing) supply houses. There are choices there.

No, standalone. But: you could easily build one using a PC's parallel port and a bit of software if you are running an early version of Windows, or running DOS (to allow easy access to the port).

If your PC has a game controller that is another option, but these have fewer ports for output.

Even a couple of serial ports (the control lines) could be made to work for your needs if you don't need a big countdown. (say a single amber then green)

I'm thinking of something a bit more complex than simple running lights, and more accuracy than a 555. I /have/ been considering a

4017, fed from a 4060 14-stage counter with a 32.768 KHz crystal oscillator to get the 0.5 sec countdown. Then there will be the detectors for position and foul starts, etc.

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OK. Thanks for the reply.

I've found out a bit more about that side of the matter. Portatree seems to offer low-cost solutions. But "low-cost" is relative and customs hassles make it impracticable to buy from such sources (I'm in a remote corner of India). In any case, I asked about prices mainly to get an idea of what's involved with commercial products.

Again, that question was mainly to get a feel of how it's usualy done. I'm not so hot with programming and a computer-controlled option will still involve designing and building the external hardware like sensors, power supplies, lamps support structure, lamp drivers, etc. Given the limited amount of time available, I think I'll stick to a purely hardware approach.

I've been thinking of using a crystal oscillator-counter with a 2 Hz output - probably a 4060 - and good old 4017 decade counter, latched at the 4th pulse.

There's still an important gap in my understanding of how it all works. The sources I've read say that the prestaging and staging points are detected with two beams of light, 7 inches apart, near the starting line. Fine, I guess I can use laser pointers and photosensors coupled with the countdown circuit. The gap is that none of the sources say how a foul start (before the green GO light comes on) is detected. No mention of a third beam.

Since the staging detector beam is already cut off by the vehicle's front wheel before the countdown begins, I don't see how that can be used. Detecting the instant the front wheel /leaves/ the beam seems unsuitable as variations in the size and design of the wheel will introduce a factor of uncertainty. Can you or anyone else provide some enlightenment?

Puzzle solved (I think). Although I have not seen a specific statement to the effect, I've come across some indication that the time a racer leaves the starting line /is/ taken as the moment the front wheel leaves the staging marker beam, thereby no longer blocking it.

I also read that the beam is placed about an inch above ground. At that height, the wheel of a car or bike would be roughly a foot wide. From a standing start, the time taken for a part of that foot-wide section to cross the beam will be an appreciable fraction of a second. As a point of academic interest, that's quite significant when reaction and elapsed times are measured to within a millisecond.

You don't need precision timing for the Xmas-tree, just so it's consistent from light to light, so the driver has a sort of countdown.

As far as staging beams, the vehicls stops at the first beam, with some kind of "ready" indicator. If the vehicle interrupts the second beam befor the tree goes green, then it's a foul. Is there some kind of structure between the two lanes at start? That way you could have two "foul" beams, so you could tell which one fouled.

So, press the "ready" button, the red light at the top of the tree comes on, and if the contestants are "staged", you're ready to go Maybe put some kind of interlock, so you can't start until both vehicles are "staged". Operator presses "Go" button, the tree counts down, and as soon as the green comes on, send a "start" signal to the timer at the end of the track. I don't know how you'd arrange for two "finish line" beams without something between the lanes, but when somebody wins, who cares what the loser's time was? ;-)

Good Luck! Rich

Close but no cigar. Interrupting the first beam lights the Pre-Staged light. Interrupting the second beam lights the Staged light. When both cars are staged, the Starter initiates the tree. Uninterrupting the first beam before the green light lights the Foul light.

A handicap can also be dialed into one side of the tree. I've seen a 19-second car run against a 14-second car in bracket racing.

According to what I've learned these past few days, even *that* is still not quite correct. Going past the first beam before the start (called "deep staging") is usually allowed, but it carries the risk of also going past the second beam and being disqualified.

If you have a parcel service like UPS, I think Digikey will deliver parts, but other shops can deliver full systems, too, if there are no export restrictions to your place.

3 weeks is not much time for building a professional system. The low-cost solution: Some switches, some lamps and a human operator (someone sitting beside the start line and switching the switches while watching for false starts :-)

--
Frank Buss, fb@frank-buss.de
http://www.frank-buss.de, http://www.it4-systems.de

Thanks for your interest, but no way is that possible. In this remote place - really the most isolated state in India - I can't even get things shipped quickly from another state.

It's an interesting project but the short time available is frustrating, especially since I've never anything similar to this before. But the fully manual option is just not acceptable (I assume the suggestion was made tongue-in-cheek :)). They might just as well count 1-2-3 with a megaphone.