AVR-Chat

Most windshield rain sensors use the index of refraction principle; however, the difference between "full" and "just wet" isn't very much.

Tim Gilbert
JEM Innovation Inc.
303-926-9053 (office)
303-437-4342 (cell)
720-890-8582 (fax)
www.jeminnovation.com
www.pdksolutions.com

  ----- Original Message ----- 
  From: Robert Tilden 
  To: AVR-Chat@yahoogroups.com 
  Sent: Tuesday, January 13, 2009 8:14 PM
  Subject: RE: [AVR-Chat] Liquid level measurement


  Perhaps an IR reflection sensor on the outside. There may be enough of a
  difference in index of refraction between air and liquid on the inside that
  there will be a reflection from the air/plastic interface when empty and no
  reflection when full. If you can use separate emitters/sensors you could
  adjust the angle of incidence to optimize the signal difference.

  Capacitance sensing would work as well, but would need more circuitry. 

  -----------------------------------
  Bob Tilden, tilden@northwestern.edu
  High Energy Physics Group
  Northwestern University

  -----Original Message-----
  From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behalf
  Of Enki
  Sent: Tuesday, January 13, 2009 7:44 PM
  To: AVR-Chat@yahoogroups.com
  Subject: [AVR-Chat] Liquid level measurement

  I need to measure the liquid level inside a transparent plastic 
  bottle. I need to know when the liquid is below half bottle height and 
  when the bottle is almost empty. Just two steps.
  The plastic bottle measures 12cm high x 8cm x 3cm.
  I'm not allowed to insert any probe in the bottle.
  There are four bottles side by side.

  I was thinking on metal plates mounted on each side of each bottle 
  and using the capacitance method.

  Or a B&W video camera and some processing. I could generate four 
  sample windows on each video line and integrate the samples. The four 
  integrated signals would represent the liquid level on each bottle.
  An ATMEGA48 would do the level measurement with four ADCs.

  Comments, please.

  Thanks,
  Mark Jordan

  ------------------------------------

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