floppy disc drive

This is a much simplified version of the circuit published in the April 1984 issue of E/ektor, but it is, unfortu- nately, not usable with all disk drive motors. First, a recap of the operation. The drive motors are switched on when one of the drives is accessed by a DISK SELECT signal. There is a delay of a few index pulses before access proper to give the motor speed time to stabilize. A few seconds after all the drives have been deselected, the motor is switched off. This arrange- ment reduces operation of the drive mechanisms, the heads, and the disks to a minimum, which ensures a longer life of these devices. In contrast to the earlier published article, the READY output of the drive mechanism is used, wherein lies the reason that the older circuit cannot be as compact and simple as the present one: it has to take into consideration that not all drive mechanisms have this output. However, as far as we can find out, most drive mechanisms do have it, but there must be some, of ...