[xavi]

(09-13-2013 06:28 AM)Nicola Wrote:  

(09-10-2013 12:59 AM)xavi Wrote:  Hello Nicola, welcome to the forum

1.- Cheap solution is to measure first the reaction time on take off, and then measure run:
a) take off: no platform. photocell connected to push button, athlete is with the foot just behind the photocell. When you press the button, athlete see the green light changing on Chronopic, and then he runs. When photocell is touched it ends.
b) run: athlete on contact platform has to run to photocell. (no reaction time).

2.- More expensive solution is to have button and two photocells and measure all together.

In my opinion, solution 1 it's ok.

Cheers.

Thanks for the reply, but I want to know the time that goes by:
1) I press button - lights light up the detachment of the foot off the ground
2) total time from when I press button until you arrive 30 meters barrier or platform
If I'm not mistaken I think the only solution is to have two cronopic.
But my fear is that the athlete must always start with one foot on the platform then the circuit is closed.
From this condition I have to press a button to start.
If I use two cronopic solve the problem? Can you explain how?
thanks

Hello

You can use two Chronopics, but the problem in this situation that they have to be synchronized. To synchronize, one solution is to push them at the same time, but this is not precise, there's always error. It's better to have some electric connection to send send the synchronizing signal to both. We are not currently selling this, maybe we can do it, but it's better if you ask any electrician friend or someone in your workplace that makes it. Then, protocol is:

1st chronopic is connected to contact platform
2nd chronopic is connected to start push button and photocell at the end of the 30m
both chronopics are also connected to a new push button used to synchronize

Athlete is outside the platform
You click on a reactive jump test (unlimited is ok). Jump protocols is better for this because you will know contact time and flight time.
Press "Start" on Chronojump.
Then you synchronize both Chronopics with a push button connected to both.
Then person gets in the platform
Then you when person is prepared, you push your press your button
Then athlete see signal and runs.

You will need to do some arithmetic operations in order to get the correct time.
If this is ok for you then we can continue thinking on this.

BUT in my opinion is a lot better to have only one Chronopic, a photocell just in front of the foot, and another photocell at the end.
You press start button and then the person start running. When foot leave the ground is detected by the photocell.

Cheers