Measuring Large resistances
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From: Kreyen on 12 Nov 2009 15:12 I am having problems trying to measure resistance values above 100MegaOhms. My Laboratory Ohmeter gives unstable values. Is ther anyway apart from the usual dc bridges of getting accurate resistance measurements. Thanks guys. Kreyen
From: Jan Panteltje on 12 Nov 2009 15:23 On a sunny day (Thu, 12 Nov 2009 21:12:29 +0100) it happened Kreyen <Ihatespam(a)nospam.com> wrote in <biqof5tmr1nlhjrj5ogpm02cg126it0j7n(a)4ax.com>: > >I am having problems trying to measure resistance values above >100MegaOhms. My Laboratory Ohmeter gives unstable values. > >Is ther anyway apart from the usual dc bridges of getting accurate >resistance measurements. > >Thanks guys. > >Kreyen Sure, 100 volt in 100 MOhm = 1 uA. How accurate can you measure current?
From: pimpom on 12 Nov 2009 15:29 Kreyen wrote: > I am having problems trying to measure resistance values above > 100MegaOhms. My Laboratory Ohmeter gives unstable values. > > Is ther anyway apart from the usual dc bridges of getting > accurate > resistance measurements. > Are you trying to measure a resistor or something else? What range variations are you getting? Did you consider surface leakage and other interfering factors? What level of accuracy do you need?
From: Kreyen on 12 Nov 2009 15:39 On Fri, 13 Nov 2009 01:59:20 +0530, "pimpom" <pimpom(a)invalid.com> wrote: >Kreyen wrote: >> I am having problems trying to measure resistance values above >> 100MegaOhms. My Laboratory Ohmeter gives unstable values. >> >> Is ther anyway apart from the usual dc bridges of getting >> accurate >> resistance measurements. >> > >Are you trying to measure a resistor or something else? What >range variations are you getting? Did you consider surface >leakage and other interfering factors? What level of accuracy do >you need? > I'm trying to measure 3 resistances to be used for calibration purposes.. I'm getting variations of several percent while I'm looking into a t least a 0.1 percent accuracy level. Kreyen
From: Kreyen on 12 Nov 2009 15:45
On Thu, 12 Nov 2009 20:23:48 GMT, Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: >On a sunny day (Thu, 12 Nov 2009 21:12:29 +0100) it happened Kreyen ><Ihatespam(a)nospam.com> wrote in <biqof5tmr1nlhjrj5ogpm02cg126it0j7n(a)4ax.com>: > >> >>I am having problems trying to measure resistance values above >>100MegaOhms. My Laboratory Ohmeter gives unstable values. >> >>Is ther anyway apart from the usual dc bridges of getting accurate >>resistance measurements. >> >>Thanks guys. >> >>Kreyen > >Sure, 100 volt in 100 MOhm = 1 uA. >How accurate can you measure current? Well we got this expensive meter at the Lab at work so I can't see how accurate its current abilities are ... as I'm now at home sweet home . But I'll check tomorrow and let you know the values. It is a HP and a very professional looking device though. Kreyen |