Re: DIY Magnetic Stirrer

On Dec 15, 10:09 am, D from BC <myrealaddr...@xxxxxxxxx> wrote:
On Sat, 15 Dec 2007 17:28:18 GMT, JosephKK



<joseph_barr...@xxxxxxxxxxxxx> wrote:
D from BC myrealaddr...@xxxxxxxxx posted to sci.electronics.design:


<snip>

On Dec 13, 8:57 pm, D from BC <myrealaddr...@xxxxxxxxx> wrote:
Then perhaps do an electromagnet arrangement like:

(3)
S
N
NbarS *Top View*
S S
N N
(1) (2)

Then try to get the bar magnet spin with a primitive 1,2,3 switching
of each C coil.
Ex: To get the permanent magnet N to follow the electromagnet S from
1 then 2..then 3.

Hopefully the bar magnet doesn't zoom away from the center.

D from BC

The electromagnet relative polarity is dependant on the direction of
the current in the coils. So if you have a consistent winding
orientation the start and finish become more important. Then use
waveforms more like this:

------ ------ ------- +
A: --- --- --- --- --- --- --- 0
------ ------ ------ -

------ ------ ------ +
B: --- --- --- --- --- --- 0
------ ------ ------- --- -

--- ------ ------ ------ +
C: --- --- --- --- --- --- 0
------ ------ ------ -

Preferably active at all levels but open for 0 will still work.

mmmm... bipolar drive.. Field reverses.
Heyyy...are those stepper motor waveforms??
If so, I guess I can just browse the stepper motor IC's. Maybe
something with built in H bridge outputs.

At first I thought unipolar drive. No field reversal. I was thinking
it might simplify the electronics. But...I'll guess there's something
wrong with that... low bar torque or poor/no function.

D from BC

Had to use google, my ISP is misconfigured currently.

The object is a rotating magnetic field. You could run it in a
unipolar way, just shift the waveforms up. Three steps is not
actually neccessary, there are three phase hobby motor
controllers (like used for RC cars, planes, boats, and heli's).
Not too expensive and would do the job nicely. You may
have to wind a lot more poles to get the speeds you want
though.
.

Relevant Pages