Instrumentation Query

Replies

• 

  Ramani Aswath

  usmanmalik;166535 that is when liquid level changes

  It is not clear what is called natural frequency of liquid. As far as I know, there is no such level dependent property of liquids. In a tank if the level of liquid changes, the resonant frequency of the gas space above changes. While it may be possible to use this to detect liquid level there are far simpler and cheaper methods to sense liquid level.
  Is there a special reason to go for this frequency method.
  It should be pointed out that what is given above is specific to each tank. The frequency pattern will change for a differently shaped tank.

• 

  usmanmalik

  Thanks for reply !!
  actually there is any liquid in tank..when liquid level rises or falls, natural frequency of that tank changes..i wana know devices to sense these changes !!
• 

  Ramani Aswath

  usmanmalik

  actually there is any liquid in tank..when liquid level rises or falls, natural frequency of that tank changes..i wana know devices to sense these changes !!

  There is nothing like natural frequency of the tank. The air space above the liquid can have a resonant frequency. Is that what you refer to?
  This is what happens in wind musical instruments. By closing holes in the body of the flute you produce different sounds.
  
  Though unusual, you can have a small tube projecting out of the tank and blow air across the tube mouth. The resulting sound can be analysed and converted into level.
  Too much effort for too little returns.
• 

  usmanmalik

  sir i want to measure liquid level by sensing natural frequency.. i want to know some practical devices used in industry and principles on which they work
  if u provide some information on these device or links, it will b very helpful for me 😀
• 

  Ramani Aswath

  usmanmalik

  sir i want to measure liquid level by sensing natural frequency.. i want to know some practical devices used in industry and principles on which they work
  if u provide some information on these device or links, it will b very helpful for me 😀

  In my opinion your best bet is to monitor the frequency of the whistle using the height of liquid column in a monitoring tube. This tube can be even outside the tank connected at the bottom. While you can make your design common to any tank by using a standard diameter tube, your instrument will have to be adjusted for each tank, which is impractical.
  
  Frequency will be proportional to the level. See this:
  #-Link-Snipped-#
  Resonance_and_Speed_of_Sound_Lab
  
  This site gives almost exactly what you want. If you replace the small cylindrical water tank on the right by your container, you have what you described.
  
  PDF
• 

  silverline009

  hi can somebody tell me what will happen if a square wave is used as a source of excitation in LVDT instead of sinusoidal one???
• 

  usmanmalik

  thanks sir !!
• 

  pparasar

  silverline009

  hi can somebody tell me what will happen if a square wave is used as a source of excitation in LVDT instead of sinusoidal one???

  ..Dude there would not be any movement at all, as you need sinusoidal current to induce the currents in secondary coils and that's not possible with square waves. the movement requires gradual changes in current not a sudden one to produce the required effect. this is very basic working of LVDT. you may refer some notes on lvdt...😀
• 

  chetan sakariya

  because when liquid level change then small partical acedent each other and produce some frequncy wawe.........that,s my view........
• 

  piyuangie

  hello sir
  sir i want any project which would include biomedical+instrumentation both
  plzz help me out as soon as possible...
  but yeah there should be something innovative in the project..
• 

  Ramani Aswath

  One instrument that is required is the Hemoglobinometer. Talk to a blood bank in your area to get additional info. If you can make a simple one using a suitable colour laser LED, a suitable photo-transistor and AA cell powered, it will be useful to rural areas.
• 

  piyuangie

  bioramani

  One instrument that is required is the Hemoglobinometer. Talk to a blood bank in your area to get additional info. If you can make a simple one using a suitable colour laser LED, a suitable photo-transistor and AA cell powered, it will be useful to rural areas.

  hmmmmm.....thanks for the suggestion & if i want an only IC project then what would you prefer to me..