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

    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.
    Last edited: Aug 17, 2010
  2. mcgyvr

    AAC Fanatic!

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

    Thread Starter Member

    May 11, 2010
    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
    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 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.