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Article #62Re: Capacitor Sensor/Meter
From: Spehro Pefhany
Date: Wed, 18 Jun 2003 14:27
Date: Wed, 18 Jun 2003 14:27
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3152 bytes
On Wed, 18 Jun 2003 12:24:03 GMT, the renowned no_spam@aol.com (Bob Masta) wrote: >On Wed, 18 Jun 2003 11:53:17 +0200, "Iman Habib" ><imanhabibREMOVETHIS@eml.cc> wrote: > ><snip> >> >>After some thinking I came to the conclusion that capacitors would be >>an excellent choice. The idea was mostly due to the digital calipers >>I have. It has an accuracy of 0.01 mm and I read somewhere that >>the sensor is essentially a linear capacitor strip running inside the >>calipers slider. And I thought the actual electronics shouldn't be that >>expensive as the caliper itself costs about 30$. >> > >Don't your calipers have a long rack and pinion gear like the old >dial calipers? I assumed the digital encoding was strictly rotary. >If it uses capacitors, it is probably in the same way that you would >use a slotted disk with photo-optical methods: strictly for counting. >That will give you best accuracy and linearity. The calipers use a crude (crude probably isn't the best word) fingered capacitor arangement, perhaps 0.1" (give or take half an order of magnitude) between "plates", and interpolate between to give 0.0005" or 0.01mm resolution. There's no rack and pinion to pick up dirt like the old dial caliper, they are mechanically just like the vernier style. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
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X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 112d1e,c351c34f78e51f4c X-Google-Attributes: gid112d1e,public X-Google-Thread: 111d0a,c351c34f78e51f4c X-Google-Attributes: gid111d0a,public X-Google-Thread: 1118be,1268c95264c97a85 X-Google-Attributes: gid1118be,public X-Google-Thread: 103407,1268c95264c97a85 X-Google-Attributes: gid103407,public X-Google-Thread: 107cee,1268c95264c97a85 X-Google-Attributes: gid107cee,public X-Google-ArrivalTime: 2003-06-18 07:27:55 PST Path: arc1-ca.pugleaf.net!archiver1.google.com!news1.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!newshosting.com!news-xfer1.atl.newshosting.com!newsfeed.mountaincable.net!cyclone01.bloor.is.net.cable.rogers.com!news02.bloor.is.net.cable.rogers.com.POSTED!not-for-mail From: Spehro Pefhany <speff@interlog.com> Newsgroups: sci.electronics.basics,aus.electronics,sci.electronics.components,sci.electronics.design,sci.electronics.misc Subject: Re: Capacitor Sensor/Meter Organization: Rather Message-ID: <mlt0fv4mhu3ajuuveld9aqs97n4c8a2e5h@4ax.com> References: <bcpcqc$lie1q$1@ID-168056.news.dfncis.de> <3ef057df.1666060@news.itd.umich.edu> X-Newsreader: Forte Agent 1.93/32.576 English (American) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 35 Date: Wed, 18 Jun 2003 14:27:55 GMT NNTP-Posting-Host: 24.112.151.88 X-Complaints-To: abuse@rogers.com X-Trace: news02.bloor.is.net.cable.rogers.com 1055946475 24.112.151.88 (Wed, 18 Jun 2003 10:27:55 EDT) NNTP-Posting-Date: Wed, 18 Jun 2003 10:27:55 EDT