Ideas..are welcome wanna make a laptimer..

[TKS]

hi all,

i'm a racer and i wanted to know if it is possible to build a laptimer using..

a sender on the wall @ 1 point of the circuit and a reciever in the car

when the sender /reciever passes east other @ the higest level of recievement he stoppest the watch and startst the next round..

any one ideas..??

and how can i make a close sender / reciever lets say 11 meters..???


TKS

 

[DirtyLude]

I've been thinking about this as well, and I can't think of anything good.

All the ones I've seen require equipment on both sides of the track. I'd like something I can just setup on the side of the track that isn't in the way, that way I can time and datalog practice sessions.

I was thinking RF to identify the car with some kind of tripper on the car itself, but IR would be overwhelmed by bright daylight and a laser diode is too narrow.

Dealing with RF alone, I've found it too difficult to figure out some kind of scheme to trigger on the falling edge of the signal strength.

 

[TKS]

mhhh

i was thinkking...

that if we use a microcpu we could build it easyer

like this..

if we build a small receiver/sender

the sender unit we place @ the start finish line..
(we create it that way that it has 11 meters of range..)

when the reciever recieves its signal it starts the time..

(then because it keeps recieving we build a timer in for 10 seconds..)

soow we are well passed the range..

then it keeps scanning for the signal and then..when we did the round it
locks the time and resets the clock again...

a microcontroller can be very accurate..and fast to do the job..

better is to use a chip from philips wich has a clock inside..it..

(or use 2 pic's..) 1 for the clock and 1 for the start and stop etc..

i think i2c is enough for this..

maybe 1 pic is also enough..


if you draw a circle of 11 meters and you imagine the walls than you can calculate how accurent it is..(offcourse it depends of your speed..but if your speed = 11meters a sec.. then our timer will be as accurent as 1 sec..

(if you pass the symolic range not every lap @ the same place..

i place it @ zandvoort where we reach a speed of 190Km/h..
that's +/- 50meters a second.. that means 50/11 =x acc= 1000/x

= 200miliseconds.. in the very **** event..

(our range should be as minimum as the street is withd if you untherstand my idea..??

out timer is

TKS

 

[DirtyLude]

You can use whatever microcontroller and only 1 would be needed. You can interface with a Real Time Clock (RTC) chip for time, and if you set it once, you could sync it up with any datalogs you might make as well.

Using RF range won't be all that accurate with a single receiver, and I've found that too many things effect range for it to be usefull as a good measure of distance. Maybe a directional antenna or something would work, but I'm not good with RF and I've found antenna tuning and general RF to be pretty complex if you want to do it right.

I'm not good at RF all together, but the idea I outlined above should be the best RF solution. No matter which side of the track you are on, as you get closer the receiver the signal will strengthen, until you pass the receiver. As soon as you pass the receiver the signal will weaken. If you can log the signal strength, whenever the strongest signal was recorded on the pass by will be the time you passed the receiver.

This should be equally accurate if you pass the receiver on the inside or outside of the track.

Of course, I'd like to see a none RF solution if possible. Like I said, RF has not been kind to me.

 

[gtrman1992]

I am almost finished this project. Don't worry about a RTC just get a crystal running at 3.768MHz for 1/100sec or 18.432MHz for 1/1000sec

 

[DirtyLude]

I am almost finished this project. Don't worry about a RTC just get a crystal running at 3.768MHz for 1/100sec or 18.432MHz for 1/1000sec

That's fine to recording the actual elapsed time, but it would better to attach an actual time of day and perhaps a date to the elapsed time log. It would be easier to keep better logs of lap time improvements over a season or even multiple seasons.

It would also allow you to match them up with in car datalogs with date/time stamps on them, which I'm also working on.

Of course that's all just secondary to getting the correct elapsed time.

Do you want to elaborate at all? No offense, but I've seen it happen quite often when someone kills a discussion by saying they've almost completed a project, and then never updates anything.

 

[TKS]

Well

i hope you can post comse information on how you did you project and what kind of components did you use...


personally taken i'm more a computer man..
and microcontroller man i don't know nothing about signal stregst..

i only know.. that if you cut a atenna the signal is broken
and the range may improve or be weak and les stable etc

whit other words radio grapgy trasmission is like hokus spokus for me..


TKS