TAOS will sell you a neat linear CCD test board for about 99$ production cost on the Lccd would be about 20$ for the sensor and maybe
15$ for a laser diode and collimator. The test board has the clock and logic to hook to a scope, but you'd need a pretty fast micro to decode it.Steve Roberts
Why a triangle wave rather than sine? Are the HF harmonics essential?
-- Dirk The Consensus:- The political party for the new millenium http://www.theconsensus.org
yes, you need the harmonics, and a triangle gives you a linear output, sine is somewhat nonlinear and much less sensitive. I'd have to go down stairs and pull the research notes and sources, and I cant get them till monday, but I can get you a schematic from my notes. Its been two months since I worked on the thing, and I was basically mentoring a grad student who did the design. With 5 labs, two professors, 4 postdocs and 18 grad students, my mind gets fuzzy on fridays.The basic concept came from one of those "Ready Circuits Handbook" by Markus on measuring small caps.. there is a Linear Tech App note that uses Linear's flying cap bridge chip that comes to mind, we tried it, but elected to go with the cheaper circuit.
See:
also
and
we simplified the daylights out of it compared to the above circuits. The main office is closed and I need to go off campus to get to a scanner, but I will send you ours soon.
Steve
schreef in bericht news: snipped-for-privacy@g44g2000cwa.googlegroups.com...
It's been a while I looked at these kind of linear sensors, but only the small ones that were made by Texas Instruments. I see there are some very nice large ones available now, about 10cm total lenght. I could have used those, ~6-8 years ago ;)
-- Thanks, Frank. (remove \'q\' and \'.invalid\' when replying by email)
"Dirk Bruere at Neopax"
** OK - so it is a sub woofer.Right ?
** Dirk - when are you gonna wake up that knowing how to write program does NOT make you design engineer ?BTW:
The tried and proven way to add "motional feedback " ( MFB ) to a woofer is to attach an accelerometer to the cone.
Philips (et alia ) did it back in the late 70s.
....... Phil
more on capciflectors
Steve
Is that an absolute accuracy requirement or just the resolution?
The straightforward way to do it would be with a LVDT.
production...
Could you mount a Heidenhain LIP scale vertically on your oscillating surface?
You could do non-contact interogation with their photoelectric sensor to the sort of precision you seem to need. Maximum speed is limite to
72m/min, which is too slow to follow a circuit vibrating through 50mm at 100Hz, but better photodiodes and photodiode amplifiers could probably fix that.-- Bill Sloman, Nijmegen
On 3 Feb 2006 12:31:08 -0800 in sci.electronics.design, snipped-for-privacy@uakron.edu wrote,
What does "non-contact" mean? Perhaps the far side is already a suitable capacitor plate. But if you put another plate near it, and put an AC or DC charge on it to measure the capacitance, it is then going to exert some force on the plate being measured, no?
I'm just searching for possible approaches at present to check feasibility. Whether the overall project is feasible, even if I can do this, is a moot point at present.
-- Dirk The Consensus:- The political party for the new millenium http://www.theconsensus.org
Well given that the thing I want to measure is being driven by a kW power source I don't think that will matter.
-- Dirk The Consensus:- The political party for the new millenium http://www.theconsensus.org
Thanks a lot. The possible solutions seem to be optical or capacitative. The latter is of more interest since I have another project where I intend to do linear measurements using cylindrical caps over longer distances, albiet less accurately.
-- Dirk The Consensus:- The political party for the new millenium http://www.theconsensus.org
Sort of...
I've heard that one before. BTW, I started as a physicist and then moved to EE design before getting into s/w. Never stopped me making money, nor making products that have multimillion $ sales for my employers.
Check my CV and the projects list
And there is no better way of doing it now, despite DSPs with GFLOPS costing $20. Excuse me if I ignore the 'it can't be done' advice.
BTW, I do know how it is done already by people like Velodyne.
-- Dirk The Consensus:- The political party for the new millenium http://www.theconsensus.org
production...
I'll look into it. Thanks
-- Dirk The Consensus:- The political party for the new millenium http://www.theconsensus.org
"Dirk Bruere at Neopax"
** So it is.** Makes you are even bigger FUCKWIT than previously thought. ** Shame you are still totally clueless about the real world of electronics design and manufacture.
Every word you post proves that again and again.
** Makes you are even bigger FUCKWIT than previously thought.Plus pig arrogant and barely literate.
What a fraud and a charlatan you are.
........ Phil
I think our readers will be the judge of which one of us is the obnoxious f****it.
-- Dirk The Consensus:- The political party for the new millenium http://www.theconsensus.org
"Dirk Bruere at Neopax"
** Makes no difference to the FACTS of the matter:"Dirk Bruere at Neopax" is yet another time wasting,
publicly masturbating AUDIOPHOOL TROLL !!!!!
PISS THE HELL OFF - DICKHEAD !!
........... Phil
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