🚀 go-pugleaf

Greetings.

Quite a while back I attempted to repair the tape deck
in my Toyota. I found that one of the plastic shafts that
rotates the casette's tape wheel had cracked, leaving a gap
in the gear teeth. I assume the reason for malfunction and
subsequent devouring of many a tape was a perpetual End of
Tape being recieved. I tried using similar salvage parts to
replace the gear but this didn't work. The reason for this,
I think, is that the original gear had a small disk magnet
fixed to its base, and beneath it was a small surface mount
component. I assume this is some sort of a tape speed
regulation. My question? The matter is rather academic at this
point, as this was a good excuse to buy a CD unit. However,
I am still very curious as to how the thing worked. Although
my EMAG is rusty, I would guess that a rotating B field was
somehow used to induce current in this sensor, which was
then used as a feedback. Does anyone out there have experience
with this type of arrangement?
Just extremely curious,

dparker@helios.ece.arizona.edu