Low cost lap-timer...interested?

[skelstar]

I did a similar thing a couple years back and made a laptimer using a BS2 microcontroller plus 4x20 LCD and mounted a trigger button on my handle bars. It was very clumsy and limited but did the basics.

I now use one of these laptimer stopwatches and wired up the lap button to my horn button and it velcros to the top of my triple clamp. It does a great job for a fraction of the price and is way more convenient. I did plan to connect up an IR sensor trigger + beacon but never bothered because it does an adequate job as it is.

So you might want to consider this before attempting to reinventing the wheel.

I think I did read your post about it (last year sometime?). I have a new implementation in the next post. Ta for the input.

[skelstar]

Heres the proposed system:
# Theres a FM transmitter on the side of the track, non bike specific. It transmits a pulse train. A certain frequency (maybe 1kHz).
# Theres a FM reciever on the bike that is tuned to the frequency the Txtr is transmitting at.
# The output of the rxvr is pre-amped into a microprocessor.
# Processor listens for 1khz pulse train in the signal from the radio. Very easy.
# Proc takes a lap time and sends to display for reading at convienient time.
# (not displayed) there will also be a button to start/stop. This allows a txtr to be placed on the end/start of a loop/route and you just have to start/stop it at one end (ie rimutakas/coro/22 etc).

Maybe we could have network around the country .

[MrMelon]

Maybe we could have network around the country .

Don't tell the govt that!

[ManDownUnder]

Hmmm...not a bad idea. Would have to make sure it didnt trigger by passing over a white line, and I dont want to determine colours (ie yellow tape). The less environmental influences the better.
Thanks everyone for the feedback though. Keep it coming! .

yeah I wasd thinking that.

The challenges are:
1) It needs to be very place specific (i.e. not triggering "about there"
2) Wide enough to be reliably hit every time
3) Trigger/signal not lost in a crowd (i.e. riding across the line with 10 others doesn't frustrate the system)

4) (to broaden market appeal) usable in cars too.

Maybe a cable hung high across the road, and the receiver pointing up with shielding arranged so the cable/signal is only "visible" for 1/100th of a second?!?

[skelstar]

yeah I wasd thinking that.

The challenges are:
1) It needs to be very place specific (i.e. not triggering "about there"
2) Wide enough to be reliably hit every time
3) Trigger/signal not lost in a crowd (i.e. riding across the line with 10 others doesn't frustrate the system)

4) (to broaden market appeal) usable in cars too.

Maybe a cable hung high across the road, and the receiver pointing up with shielding arranged so the cable/signal is only "visible" for 1/100th of a second?!?

Valid points.
If the beam is VERY specific there could, in theory, be a chance the unit ont he bike could miss it. If the beam was NOT very specifc (wide cone beam) then the accuracy goes out. Be lets be honest...the difference in time when youre nutting across the start-finish line is going to be very small. At 100km/h youre covering about 27m/s. 10 metres is alot. 1 second aint. Again I stress that this is not for the rider thats try to shave 0.2 secs off his lap time.

The 10 bikes across the line thing will have to be tested. I imagine the 'beam' signal will be scattered/diffused a bit...less so with bikes.

Easily useable in cars.

Thanks.

[skelstar]

Forgot to mention. Doesnt matter if it triggers 5metres infront of the txtr mounting point...so long as it triggers 'about' the same point each lap. Stringing wires above the track would be trouble-some I think. I wont be there to do it...in theory.

[cowpoos]

the trigger will transmitt for how far??? it won't set bikes off across the track on a different part of it will it....


what really needs to happen..........


I reckon we just get a van full of dancing girls in skimpy bikini's to the track with stop watches...problem solved...

[skelstar]

the trigger will transmitt for how far??? it won't set bikes off across the track on a different part of it will it....

Woo...thats thinking that is. Maybe it will...to be tested.
Thats thinking man! Oh...and the girls dont need the distraction nor complexity of using stopwatches when they should be DANCING!!!

[Brian d marge]

Actually if you could modify the enduro computer that was talked about in the mx thread with a simple start stop button ( small and easy to reach with thumb )

The other thing I need is a simple data logger, you can buy electronic kits that store the info and play back through a rs232 port with soft ware available on the net,
Its the potentiometer thats the biter , cheapest one I found was 160 euro ...

You see I have acces to a shock dyno, but its all guess work untill I give hard evidence.

A modified enduro computer would be mostly used to let me know if I could carry on with another lap rather than stop for gas !!!!

Stephen

[Marmoot]

You mean ACTUALLY having your missus on the track side to time you?

sorry to quote myself, but this alternative is byfar the cheapest. only cost $7 for a McD lunch for her.

[skelstar]

sorry to quote myself, but this alternative is byfar the cheapest. only cost $7 for a McD lunch for her.

Yeah but would that work day after day? ...

[Marmoot]

Yeah but would that work day after day? ...

only if you can give good satisfaction

[Bert]

Chicken .
I could have a memory, that would download afterwards through RS232. Not too difficult. Dont want to write software for computers though. Could just use a terminal program...or cycle through times on display. Real simple-like.

I might have the solution for you - software wise, as long as its a pic micro. software runs vb code and has its own screens that won't be to hard to mod to suit this application - and its free.
note some of the new pic's have built a-d converters, this could be useful for temperature logging.
A couple of us are playing with them at work at the moment.
transponder - what about a small yagi on track side sending a directional tone and a reciever on the bike that closes the circuit
PM me if you want a copy of the software.

[skelstar]

I might have the solution for you - software wise, as long as its a pic micro. software runs vb code and has its own screens that won't be to hard to mod to suit this application - and its free.
note some of the new pic's have built a-d converters, this could be useful for temperature logging.
A couple of us are playing with them at work at the moment.
transponder - what about a small yagi on track side sending a directional tone and a reciever on the bike that closes the circuit
PM me if you want a copy of the software.

I will probably use a PIC. A 16F876 if theyre still around. Im thinking of using some Jaycar FM bug type circuits and a hacked FM radio. Whats a 'yagi'...Ive not heard of this before. Is it an audible tone or ultra-sonic.
Thanks for the offer of the software but Ill be fine. Its going to be the fun bit .

[Bert]

I will probably use a PIC. A 16F876 if theyre still around. Im thinking of using some Jaycar FM bug type circuits and a hacked FM radio. Whats a 'yagi'...Ive not heard of this before. Is it an audible tone or ultra-sonic.
Thanks for the offer of the software but Ill be fine. Its going to be the fun bit .

opps - forward push aerial (work slang) - it would narrow down the transmitted beam.

I'm not sure if software writing is fun - your a twisted man, 16F876 are still around though they are getting a harder to find (though I'm cheep and only want to pay $5 for them not $11-$20).