Help with PIC chip and controlling a 230v output?

[Chems]

Hi All,

I hope you can help, I am a computer science student so I'm hopefully ok on the programming the PIC chip but beyond that I'm a bit lost.

What I'd like to try and make is a unit that can control the rotation of a small dremel type tool both in forward and reverse.

I'd like to have 4 buttons as input and have the PIC controller keep track of which have been pressed and in return control the dremel tool to rotate forward and back.

The overall objective being that 2 of the buttons will be point 0 and the other been point 10. The other two button will be increments of 1+ and -. The programming side is required to keep track of the increments so that on asking to return to starting point it will know how many revolutions to complete.

I'm aiming to control the revolutions simple on time the tool is activated for.

How does this sound and can anyone provide help in what hardware I'll need for such a task?

Thanks in Advance!

 

[OlPhart]

Sorry, this is not trivial: two answers: 1> PWM and a relay to reverse polarity, 2> PWM through an H-bridge. Neither are simple circuits because of the voltages involved and resulting hazards.
You could approach this through a dimmer pack, but it wouldn't have reverse and speed under load would suffer. I think you need some serious EE talent onboard, above student level. Good Hunting... <<<)))

 

[crutschow]

I'd like to have 4 buttons as input and have the PIC controller keep track of which have been pressed and in return control the dremel tool to rotate forward and back.

The overall objective being that 2 of the buttons will be point 0 and the other been point 10. The other two button will be increments of 1+ and -. The programming side is required to keep track of the increments so that on asking to return to starting point it will know how many revolutions to complete.

I'm aiming to control the revolutions simple on time the tool is activated for.

How does this sound and can anyone provide help in what hardware I'll need for such a task?

I don't think you can keep track of the revolutions with on time. The speed is too dependent upon load and other variables. You will either need some type of rotary encoder on the shaft or else use a stepping motor whose rotation is precisely proportional to the number of applied electrical steps.

Edit: A stepping motor is probably the easiest way since it allows you to precisely control both the position and direction of the motor shaft rotation.

 

[carbonzit]

This certainly sounds like a job for a stepper, not a universal AC/DC motor like a Dremel. You're never going to be able to control that kind of motor that precisely. (How accurate do you need, in terms of angular motion?)

 

[Chems]

I think I'll take that direction and use a stepper motor then.

Are their kits available with a stepper motor and a PIC controller. The motor doesn't need massive power just something equivilant to one of these little drills/drivers:

**broken link removed**

?

 

[crutschow]

Those drills/drivers have considerable torque since they have a gear reduction, a lot more than a dremel type tool. How much torque do you need?

 

[Chems]

Not a lot. It will be lifting 9kg weight up and down via a screw mechanism.

 

[crutschow]

I think I'll take that direction and use a stepper motor then.

Are their kits available with a stepper motor and a PIC controller.

A google search revealed several links to controlling a stepper with a PIC.