Hi Roy.

15-Feb-04 04:06:13, Roy J. Tellason wrote to Greg Mayman


 RJT> Greg Mayman wrote in a message to Roy J. Tellason:

 RJT>> No,  the data sheet specifically mentioned vcr and audio
 RJT>> cassette applications. I can see reversibility being a good
 RJT>> thing if you're running a tape cassette and have a bidirectional
 RJT>> capability in the deck -- you'd have the mechanism switch
 RJT>> capstans, but the motor would also need to spin in the other
 RJT>> direction.  VCRs? Hm,  that's a little more difficult, I'm not
 RJT>> that up on the mechanicals of those.

 GM>> The only reversable cassette player I've looked inside has the
 GM>> motor running one way all the time. The belt drive is arranged so
 GM>> the two capstans are both turning at all times, but in opposite
 GM>> directions. The pinch wheels and reel feeds are controlled by a
 GM>> solenoid operated mechanical flip-flop.

 RJT> I guess that'd be one way to do it...

 GM>> The only place I can think where you'd need a reversable motor
 GM>> with braking in a VCR is in the loading mechanism.

 RJT> Yeah,  that'd be one place.  Maybe in the capstan too?  I don't
 RJT> know enough about VCRs to be able to say,  but there are times
 RJT> when they do reverse those, for those slow-motion functions and
 RJT> such

 GM>> Years ago I saw a cassette player that could load and change
 GM>> bewteen a stack of cassettes -- that would have needed a loading
 GM>> mechanism.

 RJT> I've never seen such a thing,  though I keep hearing of such
 RJT> stuff from time to time.  For magnetic cards,  floppy disks,
 RJT> tape cartridges,  whatever,  sooner or later somebody will try to
 RJT> build a "jukebox" for them

 GM>> One intersting thing that the owner told me was that he could
 GM>> have bought an add-on that would take each cassette as it was
 GM>> ejected, and move it to the top of the stack, flipping it over on
 GM>> the way. So you could have continuous playing of up to 10
 GM>> cassettes, all the "A" sides first then all the
"B" sides, then
 GM>> repeat...

 RJT> I have a fair amount of stuff on tape,  but don't listen to it
 RJT> much.  I guess having CDs playable through any number of
 RJT> computers has rather spoiled me for sequential access

 GM>> I remember them!

 RJT>> Yeah,  weren't they nifty?  :-)

 GM>> Yes. We don't seem to have any true analog displays these days.

 RJT> Even real meters are too expensive,  it's cheaper to throw a chip
 RJT> and 3-4 LEDs at something.  :-

 RJT>> Vaseline?  First time I've heard of that being used for the
 RJT>> purpose...

 GM>> I heard of one couple that used it for sexual purposes... they
 GM>> greased the bedroom doorknob to stop the kids from bursting in.

 RJT> Heh.

 GM>> I always keep a jar handy... for strictly technical purposes you
 GM>> understand.

 RJT> It's handy.

 RJT>> I've used all sorts of assorted spray cleaners over the years.

 GM>> They work for a while, but they tend to dry up. An inert grease
 GM>> is the best as it will coat the track. The wiper can press the
 GM>> grease aside (if it is not too thick) and the grease will reform
 GM>> the seal behind the wiper.

 RJT>> Transformers fall into the category of inductors,  a class of
 RJT>> components that I've seldom gotten along with over the years.
 RJT>> :-)

 GM>> They can be a real bugbear.

 RJT> Yep.

 GM>> I once salvaged a transformer that had burned out, only because
 GM>> it had a low loss core. The laminations were made in one piece in
 GM>> the usual [|] shape but the only break was across one end of the
 GM>> centre leg where it met the outer ring. I cut the old windings
 GM>> out of the former and rewound it to 7 turns/volt to suit the core
 GM>> area. but I must have made a miscount somewhere as the secondary
 GM>> gave a lot lower voltage than it should have.

 GM>> When I did some tests I found it was closer to 10 turns/volt!

 GM>> I never could use it for the purpose I intended it for as there
 GM>> wasn't enough room left to get the volts I needed and it was too
 GM>> much trouble to remove the laminations, strip off the secondary,
 GM>> strip some of the primary and rewind the secondary.

 RJT> Winding transformer always struck me as rather too much trouble.
 RJT> :-)

I did a couple (with limited success) I'd stick a block of wood inside the
former with a metal shaft produding and drive it with a hand drill mounted
in a vice, the hearing of the hand drill gave me 7-1/2 turns of the former
for one turn of the crank. my free hand would guide the wire onto the former.

 -=> Bye <=-

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