Swimmer block departure time

[Douglas]

First, I'd like you to know that I'm a novice.

I want to record the moment that a competitive swimmer leaves a
starting block, i.e. the instant the toes leave the block. As a basis
of this, I'm thinking of using a piezo electric device, clamping this
between the block and the pool deck, and recording the change of
voltage.

An alternative idea is to use a light beam (laser) that would broken
while the toes are on the block, and made when the toes just left the
block.

Do you think any of these sounds like a reasonable way to proceed?

Thank you,

Douglas

 

[Robert Monsen]

Douglas wrote:

First, I'd like you to know that I'm a novice.

I want to record the moment that a competitive swimmer leaves a
starting block, i.e. the instant the toes leave the block. As a basis
of this, I'm thinking of using a piezo electric device, clamping this
between the block and the pool deck, and recording the change of
voltage.

An alternative idea is to use a light beam (laser) that would broken
while the toes are on the block, and made when the toes just left the
block.

Do you think any of these sounds like a reasonable way to proceed?

Thank you,

Douglas

Yes, sounds reasonable. Here is a link I found:

http://www.media.mit.edu/resenv/classes/MAS836/Readings/MSI-techman.pdf

Also, conductive foam can be used as a pressure sensor, since it's
resistance varies according to pressure. This could be a cheaper way to go.

http://www.inventables.com/i/itemview_shared.asp?ItemID=667

(I had to give my email to see the link above, so they may be soliciting
for leads.)

The laser thing would be hard to control, I think.

Don't swimmers just go on the gun? You can easily measure a sound as
loud as a gun, and use it to start a clock.

How will you measure the end of the lap? That seems a bit more difficult.

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.

 

[Larry Brasfield]

"Douglas" <mm2ps@yahoo.co.uk> wrote in message
news:4cec047f.0501191017.b7dbddb@posting.google.com...

First, I'd like you to know that I'm a novice.

I want to record the moment that a competitive swimmer leaves a
starting block, i.e. the instant the toes leave the block. As a basis
of this, I'm thinking of using a piezo electric device, clamping this
between the block and the pool deck, and recording the change of
voltage.

This would be good for recording the delay from starting gun
to launching effort. The toes off point would less distinct.

I would think you want to record also the starting gun sound.
Maybe an embedded microphone would do both jobs. I
expect that pushing off generates detectable noise and that
relative quiet would mark the toes gone condition.

An alternative idea is to use a light beam (laser) that would broken
while the toes are on the block, and made when the toes just left the
block.

Ordinary LED light would do. A simple circuit with one
NPN transistor, one NE567 tone decoder, and an op-amp
will make a sensitive thru-beam detector that would continue
to work right with water on the transmitter or receiver.

Do you think any of these sounds like a reasonable way to proceed?

Yes, more or less.

Thank you,
You are welcome.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.