[rec.audio] speed control on a cassette deck

kencr@haddock.ima.isc.com (Kenny Crudup) (09/14/89)

In article <3997@wpi.wpi.edu> reynhout@wpi.wpi.edu (Andrew Reynhout) says:
>   I can tell you from experience that altering tape speed on a cassette deck
>to any useful degree is *NOT* as simple as lining a pot through the supply for
>the motor.
>   Andrew (reynhout@wpi.wpi.edu)

True. But, rest assured for permanent magnet type DC motors, there is some
sort of speed regulation. Wow and flutter would be unbearable without
any at all.  They basically come in one of three varieties:

	- The "smart motor". This is a motor with a set of electronics in-
	  side that regulates the motor speed. Look at the back of the
	  motor. Is there a hole, possibly covered by a sticker? If so,
	  there is your adjustment point.

	- The "speed governor". This motor has centrifugally mounted
	  switches that open/close according to motor speed. These are
	  a little bit harder to adjust, as what you have to do is
	  open the motor, back in/out *both screws on the governor
	  a little at the same time*, put it together, and try it.
	  Can you say "trial and error"? I knew you could.
	  I was desperate once with one of these; but it worked.

	- The "externally regulated" motor. Walkmans usually have
	  these. There will be a pot in the motor circuit. You have
	  to look for it, and trace the circuit back. Should be fairly
	  obvious.

Hope this helps.

-- 
Kenneth R. Crudup, Contractor, Interactive Systems Co.(386/ix), Cambridge MA
Not all men are fools; some are still single! 	   Phone (617) 661 7474 x238
{encore, harvard, spdcc, think}!ima!haddock!kencr      kencr@ima.ima.isc.com