Drag race Christmas tree
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From: pimpom on 19 Nov 2009 01:44 A bike drag race is being formally organised for the first time in my state by local enthusiasts and a government department. As they can't afford a full set of pro equipment yet, they asked me if I could rig up something for them - not for free, but obviously at a significantly lower cost and, if necessary, with limited features. ATM, they are most concerned with the start line rather than with things like accurate measurement of elapsed time. Everything will have to be built from scratch. Commercial units are out of the question for now. This is not just due to cost, but also because we don't have easy access to the services and facilities you take for granted in more advanced places. I can't even ride a bike and what I know about what's needed is what I've gleaned from the internet over the past 24 hours. None of the organisers know all the details either. The event is to take place about 3 weeks from now, so I told them that I'll do some investigations but can't promise anything at such short notice. I may need help with the technical side if I decide to take up the project, but for the moment, could you please answer the following general questions first? 1. Do Christmas tree light starting systems normally come integrated with timers and sensors for elapsed time? 2. How much do they cost? I expect that this varies with the level of sophistication, but some ballpark figures will help. 3. Are they usually standalone units or software controlled from a PC?
From: D from BC on 19 Nov 2009 02:47 On Thu, 19 Nov 2009 12:14:37 +0530, "pimpom" <pimpom(a)invalid.com> wrote: >A bike drag race is being formally organised for the first time >in my state by local enthusiasts and a government department. As >they can't afford a full set of pro equipment yet, they asked me >if I could rig up something for them - not for free, but >obviously at a significantly lower cost and, if necessary, with >limited features. > >ATM, they are most concerned with the start line rather than with >things like accurate measurement of elapsed time. Everything will >have to be built from scratch. Commercial units are out of the >question for now. This is not just due to cost, but also because >we don't have easy access to the services and facilities you take >for granted in more advanced places. > >I can't even ride a bike and what I know about what's needed is >what I've gleaned from the internet over the past 24 hours. None >of the organisers know all the details either. The event is to >take place about 3 weeks from now, so I told them that I'll do >some investigations but can't promise anything at such short >notice. > >I may need help with the technical side if I decide to take up >the project, but for the moment, could you please answer the >following general questions first? > >1. Do Christmas tree light starting systems normally come >integrated with timers and sensors for elapsed time? Dunno. > >2. How much do they cost? I expect that this varies with the >level of sophistication, but some ballpark figures will help. 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. http://www.onsemi.com/pub_link/Collateral/MC14017B-D.PDF + a generic timer chip (555). > >3. Are they usually standalone units or software controlled from >a PC? > 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.
From: PeterD on 19 Nov 2009 08:55 On Thu, 19 Nov 2009 12:14:37 +0530, "pimpom" <pimpom(a)invalid.com> wrote: >A bike drag race is being formally organised for the first time >in my state by local enthusiasts and a government department. As >they can't afford a full set of pro equipment yet, they asked me >if I could rig up something for them - not for free, but >obviously at a significantly lower cost and, if necessary, with >limited features. > >ATM, they are most concerned with the start line rather than with >things like accurate measurement of elapsed time. Everything will >have to be built from scratch. Commercial units are out of the >question for now. This is not just due to cost, but also because >we don't have easy access to the services and facilities you take >for granted in more advanced places. > >I can't even ride a bike and what I know about what's needed is >what I've gleaned from the internet over the past 24 hours. None >of the organisers know all the details either. The event is to >take place about 3 weeks from now, so I told them that I'll do >some investigations but can't promise anything at such short >notice. > >I may need help with the technical side if I decide to take up >the project, but for the moment, could you please answer the >following general questions first? > >1. Do Christmas tree light starting systems normally come >integrated with timers and sensors for elapsed time? Some do come with everything, but all integrate with the system so that there is coordination between timing and start. > >2. How much do they cost? I expect that this varies with the >level of sophistication, but some ballpark figures will help. Check Jegs, or one of the other automotive (custom/racing) supply houses. There are choices there. > >3. Are they usually standalone units or software controlled from >a PC? > 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)
From: pimpom on 19 Nov 2009 09:48 D from BC wrote: > On Thu, 19 Nov 2009 12:14:37 +0530, "pimpom" > <pimpom(a)invalid.com> > wrote: > >> >> 2. How much do they cost? I expect that this varies with the >> level of sophistication, but some ballpark figures will help. > > 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. > http://www.onsemi.com/pub_link/Collateral/MC14017B-D.PDF > + a generic timer chip (555). > 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.
From: pimpom on 19 Nov 2009 10:54
PeterD wrote: > On Thu, 19 Nov 2009 12:14:37 +0530, "pimpom" > <pimpom(a)invalid.com> > wrote: > >> A bike drag race is being formally organised for the first >> time >> in my state by local enthusiasts and a government department. >> As >> they can't afford a full set of pro equipment yet, they asked >> me >> if I could rig up something for them - not for free, but >> obviously at a significantly lower cost and, if necessary, >> with >> limited features. >> ..............<snip>................ >> >> 1. Do Christmas tree light starting systems normally come >> integrated with timers and sensors for elapsed time? > > Some do come with everything, but all integrate with the system > so > that there is coordination between timing and start. > OK. Thanks for the reply. >> >> 2. How much do they cost? I expect that this varies with the >> level of sophistication, but some ballpark figures will help. > > Check Jegs, or one of the other automotive (custom/racing) > supply > houses. There are choices there. > 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. >> >> 3. Are they usually standalone units or software controlled >> from >> a PC? >> > > 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) 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? |