suggestion on wireless communication

Discussion in 'The Projects Forum' started by picaso, Jan 22, 2011.

  1. picaso

    Thread Starter New Member

    Oct 24, 2009
    Hello all

    I am making a project for measuring the liquid level inside a tank. i decided to use a 7Mhz quartz crystal inside the tank using it as an oscillator. i have to transfer the output signal of the oscillator, wireless from a transmitter to a receiver and then to a Frequency - voltage converter. I dont have to design the transmitter or the receiver. i need advice or suggestion on wireless transmitter/receiver components. the output signal from the oscillator to transmitter will be between 7Mhz and 6Mhz depending the height/pressure of the liquid on the crystal in the tank.

    Thank you in advance
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    What means do you have to change the quartz crystal's oscillation frequency with a change in volume (pressure?)?
  3. picaso

    Thread Starter New Member

    Oct 24, 2009
    i am sorry beenthere i dont fully understand what are you asking me. but i think you mean how the crystal's frequency will change with respect to volume? the crystal will be mounted at the bottom of a small tank (insulated from water), and by dropping water inside the tank mechanical pressure on the crystal will increase so the frequency of the crystal will decrease. if the the pressure is stable crystal will create a stable pulse. using a 74hct14 i can extract this pulse.
    i am not sure if a answered your question.
  4. wayneh


    Sep 9, 2010
    Why? Water pressure on the crystal's jacket does not equal pressure on the crystal. Why not use a pressure sensing IC, or for that matter, a float?

    Don't forget, pressure will depend on density and is not strictly a measurement of level. Many a tank has been overflowed for lesser reasons.
  5. picaso

    Thread Starter New Member

    Oct 24, 2009
    after a little research i did on the pressure sensing IC wayneh you made me think again about the project. i think i will have to redesign it again ...
    thank you
  6. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    There are several non-contact level sensor circuits around as well.

    Be sure to acquaint yourself with options before spending a lot of money on one that is "closest" without looking further.