Re: [CAD_CAM_EDM_DRO] Hall Effect

>
> From: "james owens" <wotisname@...>
>
> Hi,
>
> Being a novice at electronics maybe there is someone on the list that could explaine why the following cannot be done.
>
> Take a 1/4" internal diameter tube of aluminum and mill a 3/16" slot down it then fill itwith high grade ball-bearings. You have just made a very accurate scale. If you then move a Hall-Effect device alone it lenth what kind of signel do you get, is it analog or digital. If the former could the signel then be feed into an analog/digital converter the rest is easy.
>

The common way this appears to be done is using several sets of windings around the outside
or parallel to the surface.

It is simply a transformer, the signal induced in the unpowered secondary transforer
windings varies due to the induction and magnetic properties of the balls.

Exactly what the waveform would look like would be a guess, I would presume
a somewhat mishaped sine wave.

Analog Devices makes chips to interface to this type of system.

It is called Linear Variable Differential Transformer.

Look at the Analog Devices Web site for more info search on LVDT.

The chips look to vary from 20-60 bucks.

Marc