HELP! Need to measure a voltage!

Brian Dalziel

Hello,

I need to accurately measure a battery voltage with a Basic Stamp. x.x volt resolution (ones.tenths)

My original plan was to parallel-tap the 7-segment displays of an L.E.D. DMM with optos, and then connect the optos to a Stamp to scan these pins HI @ 5 volt, then using a routine to decipher the displayed numbers.

I ordered a panel-mount L.E.D. DMM recently only to find the display embedded in potting compound. DARN IT!

Has anybody else done something like this with success? Is there an LED (not LCD) voltmeter kit out there in reach of cyberspace?

I have looked at Dallas 1-wire battery management chips, but I don't have 6 months to learn how to use.

Any other suggestions appreciated!

Brian

Jon Williams

You could use an A2D like the LTC1298 to measure the voltage, and a MC14489 to multiplex 7-segment LEDs.

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Jon Williams
Applications Engineer, Parallax
Dallas, TX· USA

Jim McCorison

There is an article in the February 2005 issue of QST about a guy that built a morse code beeper to sound out the readings on his meter. He used an Metex ME-11, which has a RS-232 interface. A quick check of the web didn't find any prices, but they are listed as "inexpensive" and "affordable", although that is a relative term. A check on eBay shows a Metek M-4640A up for auction. No idea on the details other than it has an RS-232 interface as well. Current bid is $16.50 with 4 days to go. Just search on "Metek" on eBay and you'll see it.

Jim

steve_b

There is an article from Nutz & Voltz about a guy that just used a simple opto to determine 'relative' battery condition.

I've attached the article....actually, rereading the article, he just used an LED with a CDS photocell on the other end, who's resistance changed with light levels...he then used the BS1's version of an RCtime command.

Of course, you could use an A/D, but if you already have one then just connect it to the battery!

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Steve
http://members.rogers.com/steve.brady
"Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."