timing system

[complementorylex]

i need to create a system that has two gates. when the first gate i
broken it starts the timer and when the second gate is broken it stop
the timer. i was thinking about using something like this
http://www.electronic-kits-and-projects.com/3130.htm
or like this
http://www.maplin.co.uk/Module.aspx?ModuleNo=31800&doy=15m10
or like this
http://www.maplin.co.uk/Module.aspx?ModuleNo=27513&doy=15m10

oh and i need it to do it through the computer.
does anyone think its possible and quite cheap

 

[cnctut]

An old Apple computer with the 6502CPU works well for this application.
This computer has several 1 bit input ports that are addressed and can
be checked with a simple assembly language program. Bit location 1
on--start counter. Bit location 2 off--stop counter. Photo diodes or
Csd(?) will work for on/off bit switches--or of course you could use
simple wires or actual switches.

Good luck.

 

[complementorylex]

ok but im having diffuclty in finding a an apple comp like that. doe
anyone have any other ideas?
i know this is probably completely incorrect but i was thinking gettin
a USB connector and finding the red and the black wire and connectin
that to the infra red gate. (que laughter)
basically i want create a timing system like i imagine they would hav
for something like the 100 metres where breaking the first gate start
the timer and breaking the second gate stops it.
Many thanks

 

[Stan]

}basically i want create a timing system like i imagine they would have
}for something like the 100 metres where breaking the first gate starts
}the timer and breaking the second gate stops it.

Use an older Mac with modem & printer ports...first IR triggers
through modem port, 2nd thru printer port, assuming a Mac serial port
can communicate up to 100 meters from the PC. Programming the Mac
ought to be not difficult, assuming you can program.

Stan.