Re: poor mans digitizing gizmo

Hello,

Awhile back, Alltronics in San Jose, CA, then on Zanker Rd, had these
for sale as surplus for about 15 bucks... Richard may still have
them, as they didn't move real well, AIRC (I'm pretty sure they've
closed their physical store and gone "Virtual")

Hope this helps,

Ballendo

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "jchrisj7734" <jchrisj@a...>
wrote:

> If you've seen the digitizer pads that are used on some computers,
> they use a signal swept across a fairly coarse (0.1" or so) grid on
> both sides of a PC board. (The X axis is on one side Y is on the
> other). The pickup coil in the stylus or puck "sees" the signal come
> past and the circuitry imterpolates the crossing point.
>
> I don't see how to practically do this on a skin top, BUT there is
> another technology that might work and should even be adaptable to
> mounting directly on a mill (Therby dragging this message back in

the

> general vicinity of the topic.)
>
> It uses either three strip microphones or 3 pairs of microphones
> arrayed on the X, Y, and Z axis. The stylus makes a noise from a

spark

> gap or ultrasonic transducer and you measure the time it takes for

the

> sound to get to the various microphones. The resolution and range

is a

> function of the counting frequency and the size of the counting

register.

>
> This type of digitizer **could** be free-standing or even mounted

on a

> mill. If you handled the frequencies properly you might even be able
> to use it for feedback, although getting to a useful resolution

might

> be a trick, not to mention the delay involved.
>
> I could certainly see making a digitizer arm using this technology.
>
> Chris