Pages: [1]   Go Down
Author Topic: 100m race timer  (Read 842 times)
0 Members and 1 Guest are viewing this topic.
0
Offline Offline
Newbie
*
Karma: 0
Posts: 23
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Hey all! ;D

I want to make a 100m race timer with a sensor to sense the start and a sensor for the finnish, i was thinking of shining a Laser into an LDR and measuring someone run through the laser that way? what do you think? and how will i send data from 100 m away? any ideas?

Thanks
« Last Edit: June 15, 2009, 10:50:47 pm by apophisadair13 » Logged

Manchester (England England)
Offline Offline
Brattain Member
*****
Karma: 514
Posts: 31550
Solder is electric glue
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Yes a laser sounds good. However, you might want to pulse the laser and use a photo transistor and amplifier to minimise interference from ambient light.

As to getting the signal over the distance, I assume you don't want to run a long wire so I would guess that wireless would be the best. Just a straight forward TX and RX would probably do.
Logged

0
Offline Offline
Newbie
*
Karma: 0
Posts: 23
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Thanks, just a another question, why pulse the laser?
Logged

Global Moderator
UK
Offline Offline
Brattain Member
*****
Karma: 240
Posts: 24454
I don't think you connected the grounds, Dave.
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
why pulse the laser?
So that you can distinguish it from constant sunlight more easily.
Logged

"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

0
Offline Offline
Newbie
*
Karma: 0
Posts: 23
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Will just shielding the sensor work...?
Logged

Manchester (England England)
Offline Offline
Brattain Member
*****
Karma: 514
Posts: 31550
Solder is electric glue
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

It might, being a laser you could put the sensor at the end of a tube but it is more tricky to set up and you still have some problem with stray light.
Logged

0
Offline Offline
Newbie
*
Karma: 0
Posts: 23
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Do you have any other suggestions for detecting a person running past a specific point?thanks for the help
Logged

Manchester (England England)
Offline Offline
Brattain Member
*****
Karma: 514
Posts: 31550
Solder is electric glue
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

How about a web cam running some image processing software. You only need look at a small vertical bar of the image to see if something has moved and trigger the timer.
Logged

0
Offline Offline
Newbie
*
Karma: 0
Posts: 7
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

I'm looking to do something similar..  I saw this on you tube, Laser Tmer version

But wasn't sure what bits of equipment I would need.  I'm new to electronics, but not to programming..  Any advice?

Thanks
Logged

0
Offline Offline
Newbie
*
Karma: 0
Posts: 23
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

What kind of accuracy should i expect? and how long will the wireless signal take to register, approx?
Logged

Pages: [1]   Go Up
Jump to: