In Car stopwatch. Anyone?

[KMS]

Has any of you ever bumped into In Car Timer DIY kit?
I mean kind of a stopwatcg that tells you your last lap time on race/oval track.
I can not afford Hotlap or Intercomp In car infrared timing systems for 250-300€/$ But I could invest for an inexpensive DIY kit that tells laptime in car for the driver. No other functions required. I don't want to pay for Laptop interface or memory for 999laps or datalogging. Just a simple big screen stopwatch situated in car and some simple Infrared/radiosignal triggering from the track side.
Anyone ever seen anything similar?
I did the search at this forum and I found one almost similar for race horses, but it will not do in my case since the display must be inside a car for the driver to see. Also there are other cars on track at the same time so I can not use infrared gate type triggering. This must be done only from one side of the track by somekind of a beacon.<p>Anyone have any ideas? This is bit tricky I suppose But I think there must be an easy solution... I hope.

[russlk]

A modulated IR transmitter at trackside and IR receiver in the car with bandpass filter to eliminate extranious signals. The received signal latches the display and resets the counter. How many minutes and fraction therof do you need?

[KMS]

I knew that someone has an idea <p>Typically times are under 2 minutes and tenth of a second should be sharp enough. like: 1,35.4<p>How can i read time at every lap? Normally stopwatch misses every second lap. Should I use two timers and read them in turns?<p>Teemu

[russlk]

The counter reset time would be small enuf that you can neglect the error, less than .001 sec.