mak@seneca.crd.ge.com (Michael A. Kinstrey) (09/12/89)
I want a half-speed cassette deck for practicing guitar
with, and the available decks with this option are way
overpriced.
I want to install this option on an existing deck. Are
there any warnings to heed before attempting this? I would
be adding a pot of some kind to the motor control, but some (most?)
decks have a speed monitor circuit which regulates
speed fluctutations.
I will be doing the mods to a CHEAP deck, walkman, or player.
I have an OK understanding of circuitry and electronics, and
have done several small projects and modifications to boards.
My questions:
1) Do the cheap walkman-type players and office-use tape players
(< $40) have the speed control monitor?
2) If not, is the job as easy as installing a pot to the motor?
If the speed monitor has to be bypassed, where is the best place?
3) What kind of effect will the varying voltage and speed have on
the life of the motor? Dramatic or only slightly?
4) Do these type of motors only operate under a tight range of voltage?
I will be using the 1/2 speed option quite a bit.
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____________________________________|_________________________________________wbrown@beva.bev.lbl.gov (Bill Brown) (09/12/89)
In article <2245@crdgw1.crd.ge.com> mak@seneca.UUCP (Michael A. Kinstrey) writes: >I want a half-speed cassette deck for practicing guitar >I will be doing the mods to a CHEAP deck, walkman, or player. > ... >I have an OK understanding of circuitry and electronics, and >have done several small projects and modifications to boards. > >My questions: > 1) Do the cheap walkman-type players and office-use tape players > (< $40) have the speed control monitor? > > 2) If not, is the job as easy as installing a pot to the motor? > If the speed monitor has to be bypassed, where is the best place? > I've adjusted the speed on two different "Walkman" (probably somebodys' TM!) tape player/recorders. They started playing at too high a speed, altho (WARNING - EDITORIAL COMMENT) I'm not sure that was a bad thing given the stuff my kids listen to. Gets it over with quicker! (END OF COMMENT). There was a pot on the p.c. board that adjusted the speed of the tape and apparently just go crudded up and opened, opening the servo loop. Twisting it back and forth a couple of times cleaned up the contact and I was able to adjust the speed. I don't know what the range of adjustment was, but even if it isn't enough you should be able to trace out the circuit and maybe change a resistor value to get the range you want. > 3) What kind of effect will the varying voltage and speed have on > the life of the motor? Dramatic or only slightly? > I'd be surprised if it made any noticable difference. > 4) Do these type of motors only operate under a tight range of voltage? > I think that they are usually Perm. Magnet motors - they have a wide speed range and fairly good speed regulation; that is for a given applied voltage the speed if fairly constant over a modest range of torque. Since they seem to be driven by a servo of some sort (I'm not sure how they derive the, feedback, hmmm gotta look into that) you should have no big problem. -bill wlbrown@lbl.gov Disclaimer: These opinions are my own and have nothing to do with the official policy or management of L.B.L, who probably couldn't care less about employees who play with trains.