AVR-Chat

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. 

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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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