Post by thread:[EE] Ideas for a quick and dirty voltage reference

So I finally fixed the Fluke 8600A DMM I got on ebay. It appears to use its bank of four D-size NiCads instead of an input filter capacitor... when the cells go bad, the meter stops working, becase the 5V DC line is more like 2V DC +3V AC. Even though the DMM is as old as I am, Fluke has the serivce manual as a free download from their website. First class! Anyway, I'm trying to get this thing into calibration as best I can. My only other meter is a 3.5 digit Radio Shack meter that's at least a decade old, so it's not much good as a calibration reference. 0 V is pretty easy to obtain. Any creative ideas on how to get other reference voltages to calibrate this meter? Regards, Mark markrages@gmail -- You think that it is a secret, but it never has been one. - fortune cookie

At 12:47 AM 4/29/2005 -0500, you wrote: >So I finally fixed the Fluke 8600A DMM I got on ebay. It appears to >use its bank of four D-size NiCads instead of an input filter >capacitor... when the cells go bad, the meter stops working, becase >the 5V DC line is more like 2V DC +3V AC. > >Even though the DMM is as old as I am, Fluke has the serivce manual as >a free download from their website. First class! > >Anyway, I'm trying to get this thing into calibration as best I can. >My only other meter is a 3.5 digit Radio Shack meter that's at least a >decade old, so it's not much good as a calibration reference. > >0 V is pretty easy to obtain. Any creative ideas on how to get other >reference voltages to calibrate this meter? Borrow another meter. Alternatively, you can buy a 0.1% LM4041AIZ-1.2 from Digikey for 2.39 one-off (TO-92, 1.2V). Or a 10V 0.05% 5ppm/°C LT1019CN8-10 for $6.88. You can also buy 0.1% resistors for a dollar or so, which could allow you to check the resistance and low current ranges, and make a divider for low voltage ranges. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" spam_OUTspeffTakeThisOuTinterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com

> Anyway, I'm trying to get this thing into calibration as best I can. > My only other meter is a 3.5 digit Radio Shack meter that's at least > a > decade old, so it's not much good as a calibration reference. > > 0 V is pretty easy to obtain. Any creative ideas on how to get > other > reference voltages to calibrate this meter? Buy this. Quick and far from dirty. If it still works. Saturated Weston cells tend to have constant voltage. Non saturated drift with time. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=29833&item=6528655550&rd=1&ssPageName=WDVW 5 days to go, $US9.99 and no bids. May be easier to find someone with an accurate meter :-) RM

Escaped aborning. "Make your own" details added. > Anyway, I'm trying to get this thing into calibration as best I can. > My only other meter is a 3.5 digit Radio Shack meter that's at least > a > decade old, so it's not much good as a calibration reference. > > 0 V is pretty easy to obtain. Any creative ideas on how to get > other > reference voltages to calibrate this meter? Weston Standard Cell. About +/- 0.1% accuracy. Make your own (1967 style) http://www.il-st-acad-sci.org/transactions/PDF/6112.pdf Involves a few nasty chemicals but relatively easy to do. Making one would be something of an effort. Making many would not be too much harder. _____ Buy this one. Quick and far from dirty. If it still works. Saturated Weston cells tend to have constant voltage. Non saturated drift with time. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=29833&item=6528655550&rd=1&ssPageName=WDVW 5 days to go, $US9.99 and no bids. May be easier to find someone with an accurate meter :-) ______ Fascinating letter on Weston history http://weston.ftldesign.com/MulhernLetter/letter.htm RM

On 4/29/05, Bob Blick <.....bblickKILLspam@spam@sonic.net> wrote: > > > 0 V is pretty easy to obtain. Any creative ideas on how to get other > > reference voltages to calibrate this meter? > > If you live near Santa Rosa, CA, I have a few reference cells you can > calibrate to. > > -Bob Thanks, but I'm stuck in the middle of Missouri. The Weston cell is looking good to me... mad scientist gear. Regards, Mark markrages@gmail -- You think that it is a secret, but it never has been one. - fortune cookie

On 4/29/05, Russell McMahon <apptechKILLspamparadise.net.nz> wrote: > Buy this. Quick and far from dirty. If it still works. > Saturated Weston cells tend to have constant voltage. Non saturated > drift with time. > > cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=29833&item=6528655550&rd=1&ssPageName=WDVW > > 5 days to go, $US9.99 and no bids. > > May be easier to find someone with an accurate meter :-) > I know what a saturated transistor is, and a saturated solution. What's a saturated cell? Regards, Mark markrages@gmail -- You think that it is a secret, but it never has been one. - fortune cookie

On 4/29/05, Russell McMahon <.....apptechKILLspam.....paradise.net.nz> wrote: > Buy this. Quick and far from dirty. If it still works. > Saturated Weston cells tend to have constant voltage. Non saturated > drift with time. > > cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=29833&item=6528655550&rd=1&ssPageName=WDVW > > 5 days to go, $US9.99 and no bids. > > May be easier to find someone with an accurate meter :-) > I know what a saturated transistor is, and a saturated solution. What's a saturated cell? Regards, Mark markrages@gmail -- You think that it is a secret, but it never has been one. - fortune cookie

On 4/29/05, Mark Rages <EraseMEmarkragesspam_OUTTakeThisOuTgmail.com> wrote: > On 4/29/05, Russell McMahon <apptechspam_OUTparadise.net.nz> wrote: > > Buy this. Quick and far from dirty. If it still works. > > Saturated Weston cells tend to have constant voltage. Non saturated > > drift with time. > > > > cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=29833&item=6528655550&rd=1&ssPageName=WDVW > > > > 5 days to go, $US9.99 and no bids. > > > > May be easier to find someone with an accurate meter :-) > > > > I know what a saturated transistor is, and a saturated solution. > What's a saturated cell? Ok, i found it with Google: http://www.allaboutcircuits.com/vol_1/chpt_11/4.html Looks like the ebay cell, marked "1.0194 V" is an unsaturated cell. Regards, Mark @spam@markragesKILLspamgmail.com -- You think that it is a secret, but it never has been one. - fortune cookie

A FRESH AA alkaline battery is painfully close to 1.6v. Eric KE6US --- Spehro Pefhany <KILLspamspeffKILLspaminterlog.com> wrote: {Quote hidden}> At 12:47 AM 4/29/2005 -0500, you wrote: > >So I finally fixed the Fluke 8600A DMM I got on > ebay. It appears to > >use its bank of four D-size NiCads instead of an > input filter > >capacitor... when the cells go bad, the meter stops > working, becase > >the 5V DC line is more like 2V DC +3V AC. > > > >Even though the DMM is as old as I am, Fluke has > the serivce manual as > >a free download from their website. First class! > > > >Anyway, I'm trying to get this thing into > calibration as best I can. > >My only other meter is a 3.5 digit Radio Shack > meter that's at least a > >decade old, so it's not much good as a calibration > reference. > > > >0 V is pretty easy to obtain. Any creative ideas > on how to get other > >reference voltages to calibrate this meter? > > Borrow another meter. > > Alternatively, you can buy a 0.1% LM4041AIZ-1.2 > from Digikey for 2.39 one-off (TO-92, 1.2V). Or a > 10V 0.05% 5ppm/°C > LT1019CN8-10 for $6.88. You can also buy 0.1% > resistors for a dollar > or so, which could allow you to check the resistance > and low current > ranges, and make a divider for low voltage ranges. > > > Best regards, > > Spehro Pefhany --"it's the network..." > "The Journey is the reward" > RemoveMEspeffTakeThisOuTinterlog.com Info for > manufacturers: http://www.trexon.com > Embedded software/hardware/analog Info for > designers: http://www.speff.com > > > > > > -

Russell, On Fri, 29 Apr 2005 19:13:47 +1200, Russell McMahon wrote: >...< > Buy this. Quick and far from dirty. If it still works. > Saturated Weston cells tend to have constant voltage. Non saturated > drift with time. > > cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=29833&item=6528655550&rd=1&ssPageName=WDVW > > 5 days to go, $US9.99 and no bids. But... but... but... it's got Mercury in it! I'd be really surprised if that's allowed to be sent though the post, and as for the seller sending it "Worldwide", Mercury is certainly banned from aircraft. Place a drop of it on a piece of Aluminium to see why :-) Cheers, Howard Winter St.Albans, England

> But... but... but... it's got Mercury in it! I'd be really > surprised if that's allowed to be sent though the > post, and as for the seller sending it "Worldwide", Mercury is > certainly banned from aircraft. Place a drop > of it on a piece of Aluminium to see why :-) Closer to home. Take a strip of copper foil. Run a well tinned soldering iron across the strip so it leaves a solidish solder trace across the surface. Foil will now mechanically fail at solder line when stressed. RM

At 14.15 2005.04.30 +0100, you wrote: {Quote hidden}>Russell, > >On Fri, 29 Apr 2005 19:13:47 +1200, Russell McMahon wrote: > >>...< >> Buy this. Quick and far from dirty. If it still works. >> Saturated Weston cells tend to have constant voltage. Non saturated >> drift with time. >> >> >cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=29833&item=6528655550 >&rd=1&ssPageName=WDVW >> >> 5 days to go, $US9.99 and no bids. > >But... but... but... it's got Mercury in it! I'd be really surprised if >that's allowed to be sent though the >post, and as for the seller sending it "Worldwide", Mercury is certainly >banned from aircraft. Place a drop >of it on a piece of Aluminium to see why :-) What happens exactly? I don't have any mercury at home. :D

>>"Worldwide", Mercury is certainly >>banned from aircraft. Place a drop >>of it on a piece of Aluminium to see why :-) > What happens exactly? I don't have any mercury at home. :D Functionally Mercury dissolves Aluminium. They form an amalgam (which is just a fancy name for something nicely mixed with Mercury). Throwing globs of mercury onto Alumin(i)um could have unpredictable results. Not that you get to see too much accessible Al from inside a modern jetliner. RM

At 21.13 2005.05.02 +1200, you wrote: >>>"Worldwide", Mercury is certainly >>>banned from aircraft. Place a drop >>>of it on a piece of Aluminium to see why :-) > >>What happens exactly? I don't have any mercury at home. :D > >Functionally Mercury dissolves Aluminium. They form an amalgam (which is just a fancy name for something nicely mixed with Mercury). Throwing globs of mercury onto Alumin(i)um could have unpredictable results. Holes? :P > Not that you get to see too much accessible Al from inside a modern jetliner. The secret agents will immobilize or kill you much before you even finish to think to remove some cover. :P

On May 2, 2005, at 3:40 AM, ThePicMan wrote: >> Functionally Mercury dissolves Aluminium. They form an amalgam. >> Throwing globs of mercury onto Alumin(i)um could have unpredictable >> results. I think it's a bit worse than that. The mercury amalgam doesn't have the same protective oxide properties as metallic mercury, so the Aluminum in it oxidizes relatively rapidly to Al2O3 (which ISN'T soluble in mercury.) So a small amount of mercury can effectively "dissolve" a LARGE amount of aluminum (or, more accurately, it causes it to corrode...) BillW