On the Emulation of TU58s

On 2015-06-16 20:23, Mark J. Blair wrote: Bu the way. For the vacuum column drives that I know (TU16/TU45/TU77/TU78), tape movement is not determined by vacuum as such. Each column have about 8 pressure switches. When 4 have low pressure, and 4 have atmospheric pressure, the drive is happey, and the reels are resting. When the point of underpressure/pressure moves down, the reel on that side starts moving to pick up more tape, thus moving the point back towards neutral. When the point moves up, the reel starts moving to give out more tape, to move the point back down again. The more switches triggered in either direction, the faster the reel will move. The movement of the tape across the head is controlled by a third motor, which have a smaller wheel on it. The tape lies against this reel, but it's all done by friction. This wheel pretty much runs the tape across the head at constant speed, and this movement of the tape will also cause the points in the two columns to move, which in turn will trigger action as described in the previous section. Not sure where the counter-rotating capstans would fit into this either... And there is only negative pressure, and it is applied to the tape at all time. Johnny