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Neat project! > Instead of a rotary encoder to measure the tape rotation, it now uses an IR led and sensor. I don't get it; how does this work? Are there openings at certain positions in the reel that it detects the light through? Why is this better than the rotary encoder design?
Earlier quoted context omitted.
it's not, the dispenser is a jab at the kind of trinket stalls that form around holy sites. what i don't understand is how the dispenser compensates for the changing radius of the tape roll in order to measure accurately. i suspect that it doesn't.
You're right that it doesn't consider changing diameter, though I did contemplate some approaches for doing that. But, since it only needs whole-inch resolution, using the diameter of a half-full roll of tape gets close enough for novelty purposes.
Earlier quoted context omitted.
it's not, the dispenser is a jab at the kind of trinket stalls that form around holy sites. what i don't understand is how the dispenser compensates for the changing radius of the tape roll in order to measure accurately. i suspect that it doesn't.
Divine intervention, presumably. They don't bless those tape dispensers for nothing.
Talk about Baader–Meinhof phenomenon. Just a week ago I became aware of Father Ted and watched only the show with the tape dispenser because it was recommended to me by Youtube. This article is year old, and shows up now in my feed.
Yesterday I found out about the Baader-Meinhof phenomenon and now I see it mentioned! Must be the Baader-Meinhof phenomenon phenomenon.
Neat project! > Instead of a rotary encoder to measure the tape rotation, it now uses an IR led and sensor. I don't get it; how does this work? Are there openings at certain positions in the reel that it detects the light through? Why is this better than the rotary encoder design?
> Are there openings at certain positions in the reel
Yes, that's exactly it! The spool has holes, and there's an IR emitter/detector on either side. You can view the STLs on the GitHub repo or Printables and see for yourself.
It's better than the rotary encoder [for this project specifically] because it's cheaper and doesn't require the sensor to be a load-bearing part.
Earlier quoted context omitted.
You're right that it doesn't consider changing diameter, though I did contemplate some approaches for doing that. But, since it only needs whole-inch resolution, using the diameter of a half-full roll of tape gets close enough for novelty purposes.
How about measuring the linear tape motion in a similar way that laser mice measure surface movement?
I genuinely never thought I'd see Father Ted, let alone the lourdes tape dispenser on the front page of HN. What a great day.
This looks like the type of application which, if mass-produced, would have the electronics done on a $0.10 mask-programmed COB.
They could do a Mrs Doyle on that: “Go on, go on, go on, go on, goes on” Or that gives you a coup of tea instead
I mean, I wouldn't put it past Mrs Doyle if some government got in the way of her serving tea, I suppose.