Gregory wrote:I have been re-thinking the electronics for driving the frame and line scan stepper motors, but I am not sure.
Always good a rethink ,my projects at times never end as i envisioned and you never know unless you try .
A
s steppers motors are synchronous motors, the thought is to drive these directly from the sync signals using the 4046 IC as a frequency multiplier to obtain the correct stepper frequency.
Yes if you can sync the 4046 as a multiplier is a great idea as you mention below drive the line stepper up slowly those steppers are fussy at higher speeds .
The process would consist of:
1) Initially to obtain the stepper pulses using a 4046 as a free running VCO slowly ramping up to the required speed.
2) To disconnect the output of the first 4046 and replace this with the output of a second 4046 configured to operate as a frequency multiplier of the incoming sync pulse frequency (using a frequency divider), so the output frequency would be an exact multiple frequency of the sync frequency. This should provide a very stable sync as the stepper frequency would be generated directly from the sync pulse frequency and there would not be any need for speed correction, as with a phase comparator.
Interesting love to see how it go's sounds all possible
T
he only problem is that although would be in sync, the mirror position would not neccessarily be in phase with sync signal. This could be overcome by using the mirror photo diode to initially trigger "process 2" only when the sync pulse and photo diode pulse coincide which would be at the start of the mirror scan.
I used the corners of the polygon mirror as the start of the line via a opto switch it worked very well as feed back to a DC motor via a 4046 ,you really do need some form of feed back .
Does this sound feasible?
Hell yes give it go all that will happen is you will know either way i would say its worth a try ,if it works great this is the sort of hobby you have to be willing to fail to learn all you can do is try your best idea ..i will learn seeing how this go's.....all very interesting .