Quote:
Originally Posted by Fabie
but that is a much complicated task
the easy solution must be the hall sensor on the opposite side like you said
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No, i was wrong - additional pulse is not useful at all - so my fault - Sorry!
Quote:
Originally Posted by Fabie
btw
I just purchased a lot of untested 3.5hd pc drives by 10€ to experiment
it seems that some drives works and other not works
but tomorrow I will do some experiments
the first experiment I will do will be placing a magnet on the opposite side of the flywheel and check if RPM spin down to 150
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Magnet or Hall sensor is not needed - please scan PCB (make photo?) for all IC used for this FDD - i will try to find some useful data.
At first clock used for frequency reference must be half of normal - motor driver use FG coil to detect speed for flywheel - Hall sensor is probably used only for generating INDEX pulse (once per rev) - maybe it is also for R/W amp as a gate but can be verified on schematics and data sheets for IC.
Second - RDY must be Device Self ID capable (uC like small AVR or PIC seems to be OK for this - You can put all logic for MOTOR ON ans DISK SEL on uC + add all switching for 300/150 maybe even generation for reference frequency - if frequency can be programed it open world for variable speed R/W - Apple floppies can be fully read or write)