Voltage to Frequency

Discussion in 'General Electronics Chat' started by Tobias, May 23, 2011.

  1. Tobias

    Thread Starter Active Member

    May 19, 2008
  2. beenthere

    Retired Moderator

    Apr 20, 2004
  3. Jaguarjoe

    Active Member

    Apr 7, 2010
    Study the data sheet for the TC4900 part. It shows how to use it with a single ended positive supply. Also note the caveats for the -5v supply if you choose to go that way:


    The data sheet has a few incomplete sentences in it which wouldn't be expected from a company with more than 1 person like Microchip. Also, one of the circuits (I think its fig. 4.3) shows a 0.1 ohm resistor and a 0.2 ohm rheostat as part of the circuit that makes no sense.
  4. Tobias

    Thread Starter Active Member

    May 19, 2008
    Attached is the schematic for the board I built. It does give a pulse out. I am struggling with getting the offset to work correctly. The pulse out will stop when Vin is less than 4v. At 4V the FO/2 is 10hz. My understanding from the schematic was I should be able to adjust the OFFSET pot to get the pulse to start at 10hz at around 0.200mv.

    I modeled my schematic off this link

    I am using a 5K pot to adjust the Vin.
  5. Adjuster

    Well-Known Member

    Dec 26, 2010
    Taking the frequency all the way down to 0Hz may be rather problematic, depending what you want the signal for. In particular, it takes a relatively long time to determine a low frequency, so if you are representing a voltage in this way, the effective bandwidth gets less at low voltages.