Position measurement.

Which reminds me - I've seen some nice circuits I can rip off, like a handy fast audio peak limiter. Ah.. to aspire to the heights of a Behringer...

"Dick Bruere at Neopax"

Spends too much of his time pulling on his tiny DICK in public to do any real design engineering.

....... Phil

I guess that POS terminal I designed for Checkout Ltd was all a dream... Not to mention the paintshop computer I designed for ICI, and the phone line tracer I designed for BT and...

BTY, do you know Paul Dobson?

"Dick Bruere at Neopax"

You make a " nice" team.

........ Phil

Now *that* sounds like libel Phil - I'm serious. You want your account pulled?

We do at that. For those who do not know the name, Paul Dobson was the founder of Studiomaster and took it to No 2 ranking in the world behind Yamaha. Specialised in studio equipment, as the name suggests.

"Dirk Bruere at Neopax"

The only "serious" thing about *Dirk the D*****ad* is how f****ng naive the cretin is.

Partners in crime.

"Studiomaster" ( aka RSD) only made only cheap audio junk for bottom feeders.

They made ( and still make) cheap audio desks and powered mixers for pommy DJs & *garage* bands.

........ Phil

Since Paul sold the business it has gone bust at least once and been resurrected. At its height, when Paul was in charge in the mid 80s when he sold it (IIRC) it was turning over some $20m per year with a very healthy profit.

Time to do it again. Ask Pooh Bear, who used to work for him and designed some of the eqipment back then.

FFS Dirk, do what nearly everbody else does with that twit - IGNORE HIM. That's what killfiles are for.

That's

I rather like winding him up. It's 04:05am here and I'm slightly bored, although I am watching a Roger Penrose lecture from Princeton across the Net. I also have to write a brief summary of media PC configuration options.

Cant say if it works for you but I used a tv camera as a microscope(reversed lens,10cm away from camera) to measure vibration amplitude.Worked like a charm.

"budgie"

........ Phil

"D*****ad Bruere at Neopax"

Dead - but just won't lie down.

......... Phil

YAWN.......

Of course not - I've got money to make! Meanwhile, don't you need to patch the roof on your trailer?

I think that's the Landlords responsibility

Dirk Bruere at Ne> I'm looking for a small(ish) non contact solution to measure an

I would suggest to use ultrasonic interferometry. We have made such devices (see here:

If interested, we can develop such device.

Wieslaw Bicz

Collimated laser, reflector at a small angle to normal, small inexpensive linear sensor and voila. Reasonably easy to calibrate for various ranges of motion from 10 mm to at least 1 m, and 1 part in 4096 resolution and accuracy.

IIRR Polaroid used an ultrasonic distance measurement in the autofocus system for their Swinger camera. More recently, you could buy "ultrasonic tape measures" that were useful for getting rough room dimensions quickly.

As far as I know these depended on sending out a brief pulse and detecting the echo. The speed of sound in air at 20C is 343.4 m/sec, so for a 50mm maximum range the go and return time is 290usec. If you use separate transmit and receive elements, you could send out a suitably long pseudo-random binary sequence and track the correlation between the transmitted and received signal, which could let you sample faster

- probably beyond the once every 100usec being asked for.

Wouldn't the typical electrostatic transducer bandwidth be a couple orders of magnitude too small?

Best regards, Spehro Pefhany