[Driving tape] > Another solution is to avoid the problem entirely by not requiring constant > linear speed. That’s what DECtape > (the real one) does.
Sure. A number of tape drives were built that way, the HP9865 (and thus the built-in tape drive on the HP9830) is another example. > > > One is to drive the tape itself using a capstan and maybe a pinch roller. > > Then have the takeup spool > > driven too fast with a slipping clutch in-line. And a weak brake on the > > supply spool. This of course is what > > was done in audio recorders (reel to reel and cassette), Video recorders > > (ditto), etc. > > Or a variant: drive the takeup reel with a controlled torque motor and no > slip clutch. I think professional grade > tape decks may have been built > that way. They were. Or at least some semi-professional audio recorders were built like that. The Revox G36 (736) and Brennell Mk 5 among them (I happen to have both). Actually, the Philips V2000 video recorders (home machines, not professional but quite the best of the home systems) did that. They had a pair of DC motors to directly drive the 2 spools along with the capstan and head drum motors. No slipping clutches. Back tension was provided not by a light brake on the supply spool but by a suitable current through the supply spool motor in those machines. -tony
