yeah, the only way to run the kart while not moving is to put something under it so that the wheels are off the ground and turn the wheels over while they are in the air. One problem with using the axle for rpm is that it requires an equation dependant on what the axle sproket size is, and I change the sproket regulary depending what track i go to so i'd have to take the thing apart and re-program it for each different sproket. Would there be any way of having a menu on the screen to chooses the sproket size? for example, program the pic to do the math for sprokets ranging from 65 teeth to 95 and then choosing which sproket to use with a button?

 

If you plan on using an LCD, you could definately have a way to change conversion factors. Also, the little (1,2,4)x(16,20,40) LCDs are super easy to use with a micro.

 

so what sort of circiut am I looking at here? what sort od chips should I use and what do you mean by (1,2,4)x(16,20,40)?

 

Have a look at the code at ftp://ftp.epemag.wimborne.co.uk/pub/PICS/PICagoras/ which is a bike computer - it could easily be adapted to do what you want, and is designed for variable wheel sizes. As already mentioned, you only need a single sensor as you don't have any gears or clutch, a simple bit of arithmetic will convert between speed and revs - although displaying both is really a bit pointless! - but I understand it's to look good on a GCSE project!.

The LCD numbers quoted are the size of them, 1x16, 2x20 etc. it was just a shorthand method of listing them.[/quote]

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

is that link right? ie crashes when i try to click it

 

Yes, I just clicked on it and it opened fine. Try using the same address in an FTP program if you have problems with IE, or follow the web links for downloads on their site at http://www.epemag.wimborne.co.uk.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk