28 March 2014
BUILD IT YOURSELF
Using baseball as an example, when it comes to sports, umpires are usually the ones
in the 'hot seat' — especially when a close call decision is made. Sometimes a video
playback is used for confirmation, but usually umpires are pretty good at being
accurate. However, it certainly doesn't mean they can't make a questionable call now
The project in this article has proven itself to be a superb “umpire” that will make the
right decision — even among 10 inputs at once that are all within a ~100 µS time
frame. During testing, I used four phototransistors wired in a single row, one-half inch
apart. Each was wired to an identically-configured input, just as indicated in the
Figure 1 schematic.
Using a handheld IR emitter and doing it several times, I swiftly passed it over and
across the row of phototransistors as fast as I could; first from left to right with a 1, 2,
3, 4 display; then, from right to left, displaying a 4, 3, 2, 1, and not one failure!
Remove the doubt!
with this low cost,
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By John Mastromoro
A MULTI-STAGE HIGH SPEED