If the bars move counter clockwise the platter is slow, increase the frequency of the sds to correct. If the movement is clockwise then the platter is fast so reduce the frequency to correct.
If the rate of rotation of the bars does not change when you change the frequency of the sds then that would suggest the the frequency is not changing and something is wrong with the sds.
If you are changing by .01 hz it will take quite a bit to make a visible change on the strobe disk. Try changing the frequency by 5 or 10 hz and see what happens.
If the rate of rotation of the bars does not change when you change the frequency of the sds then that would suggest the the frequency is not changing and something is wrong with the sds.
If you are changing by .01 hz it will take quite a bit to make a visible change on the strobe disk. Try changing the frequency by 5 or 10 hz and see what happens.