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Slot car timing circuit

R

Ron Collins

Jan 1, 1970
0
I'm trying to put together a slot car timer for my son. I came upon a
design using and IR led and IR detector set from Radio Shack and hooking
up to the parallel port of a computer. I was able to get the computer to
register the output from the IR led but only if it was about 1 1/2"
away. Any farther and there was no response. The IR led is powered by
12V through a 100 ohm resistor. The IR detector is connected directly to
the parallel port. Am I doing something wrong?

Thanks - Ron Collins
 
T

the Wiz

Jan 1, 1970
0
Ron Collins said:
I'm trying to put together a slot car timer for my son. I came upon a
design using and IR led and IR detector set from Radio Shack and hooking
up to the parallel port of a computer. I was able to get the computer to
register the output from the IR led but only if it was about 1 1/2"
away. Any farther and there was no response. The IR led is powered by
12V through a 100 ohm resistor. The IR detector is connected directly to
the parallel port. Am I doing something wrong?

Thanks - Ron Collins

The IR detector may be designed for short distances. It may not be designed to
connect to the parallel port (voltage levels, current capabilities).

You may want to do a google search for
slot car timer
slot car timing
pinewood derby timer
pinewood derby timing

There are a number of circuits available, both build-your-own and commercial.

More about me: http://www.jecarter.com/
VB3/VB6/C/PowerBasic source code: http://www.jecarter.com/programs.html
Freeware for the Palm with NS Basic source code: http://nsb.jecarter.com
Drivers for Pablo graphics tablet and JamCam cameras: http://home.earthlink.net/~mwbt/
johnecarter [email protected] mindspring dot.dot com. Fix the obvious to reply by email.
 
R

Ron Collins

Jan 1, 1970
0
Thanks for your response. I'll have a look.
 
D

David Knaack

Jan 1, 1970
0
Ron said:
I'm trying to put together a slot car timer for my son. I came upon a
design using and IR led and IR detector set from Radio Shack and hooking
up to the parallel port of a computer. I was able to get the computer to
register the output from the IR led but only if it was about 1 1/2"
away.

If you haven't already, try shading the IR detector. A short paper tube
can often help, coloring it black with a marker might help also.
Experiment with the length of the tube.

You can also do the same with the IR LED. Sometimes the IR from the LED
can bounce off of the ground or other objects and continue to trip the
receiver. If the LED is fairly wide angle this can increase with the
distance from the receiver.

DK
 
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