IR LED and Phototransistor Array Dartboard Scoring

Discussion in 'The Projects Forum' started by mbasile35, Feb 25, 2015.

  1. mbasile35

    Thread Starter New Member

    Nov 2, 2011
    Hey everyone,

    I'm looking to add electronic scoring to a bristle dartboard and my idea is to use a grid of IR LEDs and and Phototransistors. Right now, I'm just looking into putting together some hardware and then software/ interfacing will come later.

    I'm a little confused on a few things regarding IR LEDs and phototransistors. First off, here are the parts I have found. By no means am I set on these, they just seemed like a cheap and simple place to start. LED and Phototransistor. My first concern is how many LED/ Phototransistor pairs would i need to get a precise enough reading on the dart's position. I'm thinking since a dart tip is pretty thin that I would need a good amount of pairss. I should also mention that the scoring area is going to be 28" x 28". I'm also worried that if the pairs are too close then light from other LEDs can bleed into a photo transistor. For example, if the path between LED 2 and Phototransitor 2 is broken, would the beams from LED 1 and 3 be enough to bleed around the obstruction, and cause phototransistor 2 to still receive light?

    Thanks in advance
  2. Bernard

    AAC Fanatic!

    Aug 7, 2008
    I believe that this project is dead on arrival. Assuming sansing is beam break, there is a much greater chance of hitting a sensor pair than the board & if covering whole board, it might take 25,000 pair of sensors, assuming dart point of 3 sq mm. ?? Maybe I missed something.
    Or maybe this is a large XY key-pad wiyh sensors spaced 3 mm. Now to find something like a 3 mm laser beams spaced at 3 mm. Could be done? laser at a distance with bar lens & staggered line of 3 mm mirrors, each adjustable so as to hit proper sensor.
    2nd edit. Dart can have blunt point, maybe even 5 mm dia or greator. If impact point is registered, no need for dart to stick?
    Last edited: Feb 26, 2015