View Single Post
  #3   Spotlight this post!  
Unread 12-02-2006, 19:46
Tom Bottiglieri Tom Bottiglieri is offline
Registered User
FRC #0254 (The Cheesy Poofs)
Team Role: Engineer
 
Join Date: Jan 2004
Rookie Year: 2003
Location: San Francisco, CA
Posts: 3,187
Tom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond reputeTom Bottiglieri has a reputation beyond repute
Re: Tach-like Sensor

Quote:
Originally Posted by 6600gt
It might, but you can only calculate the theoretical speed. You can also try the gear tooth sensor.

You might be able to use a decent powered led and a phototransistor. Put the ball will pass in between them and cut the light to the phototransistor. Set the interrupts to fire on the falling edge(when it reads 0). Then recored the time at that point of a timer and set the pin to fire on high next and when it fires again on high record the time again. The ball is usually a constant 7 inches, so using that and the time you can calculate the velocity. Go to radioshack and ask them.
It is more complicated but I think it will be much more accurate.
Sorry, I haven't tired it, so I can't prove it.
He wants to measure the shooting wheel speed, not the actual velocity of the ball.

Yes, that sensor will work fine. You could also use the IR sensors that came in the kit this year.