24 May
2012
24 May
'12
2:16 a.m.
On Wed, 23 May 2012, Chuck Guzis wrote:
Okay, folks are suggesting phototransistor+light
source for this kind
of thing. But I was wondering...
Does anyone know of a tape (or card) reader that uses a slight vacuum
(or positive pressure) (player piano style) to read the patterns?
Such a method wouldn't be sensitive to the material (e.g. clear
mylar) used for the medium.
Fast paper tape readers (like the Facit PE1000) have a capacitive read
head. It generates a HF, and the paper tape acts as dielectricum that
changes its constant depending on hole/no hole. This change is then
detected by the read circuitry.
Christian