neddie
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Hi to all.
I'm busy looking at controlling a small ac motor. The type you would find in a oven for instance. I think they are universal motors.
The methodology I'm using is: Detect zero crossing of mains , and then after some pre-determined time fire the triac via opto triac(moc3023 I think)
The motor will then see the portion of the waveform , up until the zero crossing again when current flow stops. The cct and firmware seem to work
OK considering the simplicity.The control range is not huge , but usable.
I have looked at another circuit that is doing the same thing , but they are doing something weird , which I'm hoping someone can shed some light on.
After the zero crossing they also wait some time before firing the triac , but here is where it differs. When they pulse the opto coupler from the micro , they don't
pulse it once for some period , they feed it a pulse train until just before zero crossing again. Surely the triac remains on after the first pulse , until zero crossing ,
so repeatedly driving the opto-> triac would make no difference , or is there something I may not be aware of in this type of application.
The other drive does seem to run a little quieter , that is the motor seems quieter. Same motor , different drive.
cheers
Neddie.
I'm busy looking at controlling a small ac motor. The type you would find in a oven for instance. I think they are universal motors.
The methodology I'm using is: Detect zero crossing of mains , and then after some pre-determined time fire the triac via opto triac(moc3023 I think)
The motor will then see the portion of the waveform , up until the zero crossing again when current flow stops. The cct and firmware seem to work
OK considering the simplicity.The control range is not huge , but usable.
I have looked at another circuit that is doing the same thing , but they are doing something weird , which I'm hoping someone can shed some light on.
After the zero crossing they also wait some time before firing the triac , but here is where it differs. When they pulse the opto coupler from the micro , they don't
pulse it once for some period , they feed it a pulse train until just before zero crossing again. Surely the triac remains on after the first pulse , until zero crossing ,
so repeatedly driving the opto-> triac would make no difference , or is there something I may not be aware of in this type of application.
The other drive does seem to run a little quieter , that is the motor seems quieter. Same motor , different drive.
cheers
Neddie.