AX 300-3 & VLLR


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Gizmo

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Joined: 05/06/2004
Location: Australia
Posts: 4810
Posted: 01:09pm 08 May 2012      

Good post Phill

That axial made a real mess of itself.

I think the liquid resistor is a good idea. The linear servo will give a fast response, and with the right brains in the controller, the load current can be adjusted quickly and precisely, not like the On/Off dump controllers we commonly use.

It will be interesting to see how it performs when the winds pick up. Heat build up in the water may be a problem, but if you use a stainless tank it should be able to get rid of the heat, if not just weld on a few cooling fins and paint it black.

Was thinking about ways to raise and lower the plates, knowing you and Pete did try a stepper motor driven thread but found it to slow. What about this below.



The stepper motor, or maybe a RC servo, is mounted out on the side of the tank, and a direct drive shaft goes throught the tank to a bearing/bush at the other side. The 4 plates are attached to the shaft and shaped as shown. 90 degres of rotation will raise or lower the plates into the liquid, quickly. The picture shows the plates in 3 positions, from full down to nearly full up.

If you have even seen the variable tuning capacitor in a old valve radio you will reconize the plate shape. A small counterweight could be added to balance if needed, and the only real resistance to movement will be wires conneted to the plates. A stepper motor would operate it from one end to the other within a fraction of a second, but I think you could also use a RC servo motor ( hobby, remote control ), the PicAxe chips have the commands to operate RC servo's, but they do jitter a bit.

Glenn.
People say 2020 is a terrible year, with the bush fires, COVID 19, and riots. But I see it as the year we woke up to ourselves.

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