measuring AC voltage in mV

Discussion in 'The Projects Forum' started by bummer, Apr 19, 2011.

  1. bummer

    Thread Starter New Member

    Apr 19, 2011
    I'm having some problems with an electronics project for a class and I was hoping someone could help. I need to build or buy a really cheap (less than $5 US or close) tool that can measure small AC voltages (1 mV to 2 V) at 50 Hz and 60 Hz.

    If anyone has any suggestions please let me know, thanks!
  2. JDT

    Well-Known Member

    Feb 12, 2009
    Do you already have a DVM that can measure AC voltages in the range of 1 - 10V?

    If you do, for measuring AC voltages in the millivolt range you could make a single op-amp type non-inverting amplifier of a known gain (say 100 or 1000) powered from a couple of small 9V batteries. Connect the output to your DVM. Put a capacitor in series with the amplifier output to remove any DC offset. 10 uF will do. AC Volt range. Divide reading by the gain.
  3. bummer

    Thread Starter New Member

    Apr 19, 2011
    Thanks for the help. Unfortunately, we don't have a DVM that can do that. I have tried looking for one but all the ones that I have found within our price range can only do 0-200-750 V.

    How much does a DVM like that usually cost? I have looked at a few DVMs and they still only say 0-200-750 VAC.
  4. Pich

    Active Member

    Mar 11, 2008
    Check on the web for full or half wave precision rectifiers.