Bare bones voltmeter with LCD

Discussion in 'The Projects Forum' started by sage.radachowsky, Aug 17, 2010.

  1. sage.radachowsky

    Thread Starter Member

    May 11, 2010
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    38
    Hello,

    I've been asked to create something that will be a small-run product, maybe making 500 or so this year. It's an educational toy for microbial fuel cells.

    Do you have recommendations for the most bare-bones voltmeter circuit with LCD?

    I'm good with microcontrollers (especially MSP430 and AVR) but perhaps there is an inexpensive, simple chip that performs just the voltmeter & LCD functions in one.

    The voltages to be measured are all under 1V and are all positive, and accuracy to about 5 mV would be good, 2 mV would be great.

    Otherwise, I might make it using a microcontroller that is specialized for operating an LCD, and also has an ADC. Any recommendations on 4 digit LCDs?

    Thanks in advance.
    Sage
     
    Last edited: Aug 17, 2010
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    sage.radachowsky likes this.
  3. sage.radachowsky

    Thread Starter Member

    May 11, 2010
    241
    38
    Thanks for the advice on the chip. It is perfect except for the price (around $8 @ 100 pcs. or so). I'll keep my eyes out for cheaper alternatives but it may be that a uC is the way to go.
     
  4. darkfish

    New Member

    Aug 17, 2010
    4
    0
    The rather old ICL7135CPI is around £2 from RS for 100 off. It has a multiplexed BCD output, so you would need an LCD driver to go with it
     
  5. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
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    $2 Chinese LCD voltmeters from the eBay sellers, some are 0 - 1.999V but read closely as many require a separate power source that's isolated from what you're trying to measure.
     
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