throbscottle
Well-Known Member
Yay, it's working!
In case anyone is still following this...
I put in a 74HC123 monostable and an XOR gate between the BSS84 and the delay stage, connected the XOR other input to the "down" flip-flop. Just put it through 200 up-down cycles with only very slight (+/- 2mm) wandering, not enough to bother correcting, and it could be down to all the flakey connections anyway. Previously I could get 50, with careful adjustment of the opto, before needing to adjust.
Hoping to use the other half of the 123 in place of the 1/2 556 monostable, but discovered it actually relies on a quirk of the 556 to set up the initial conditions which the 123 doesn't exhibit - namely that it can be held in the on state. So yet another transistor needed to add that function. But at least then it'll just be a 555 doing the PWM and the chip-select monostable gets to be in a more sensible location.
Now I just need to make it behave when the spindle motor runs - sends it all over the place!
I will post drawings of this thing when it's working properly I promise!
In case anyone is still following this...
I put in a 74HC123 monostable and an XOR gate between the BSS84 and the delay stage, connected the XOR other input to the "down" flip-flop. Just put it through 200 up-down cycles with only very slight (+/- 2mm) wandering, not enough to bother correcting, and it could be down to all the flakey connections anyway. Previously I could get 50, with careful adjustment of the opto, before needing to adjust.
Hoping to use the other half of the 123 in place of the 1/2 556 monostable, but discovered it actually relies on a quirk of the 556 to set up the initial conditions which the 123 doesn't exhibit - namely that it can be held in the on state. So yet another transistor needed to add that function. But at least then it'll just be a 555 doing the PWM and the chip-select monostable gets to be in a more sensible location.
Now I just need to make it behave when the spindle motor runs - sends it all over the place!
I will post drawings of this thing when it's working properly I promise!