Don,

What is the input impedance of your meter?  If it is less than 20
megohms or so, you'll load the FET down,
And you'll get less than expected resistance.   


	
Regards,

	
Jim 

-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
Of Don Rahmlow
Sent: Monday, January 28, 2008 12:23 PM
To: piclist@mit.edu
Subject: [EE]

I'm experimenting with analog switches/muxes ('4051 and '4066)--my first
time. When selected, the resistance of all switches is as expected, <150
ohms, but when control signal is low R varies from 20-50K among
channels, always way lower than spec. If power removed, all channels'
resistance is in spec.

My first thought was my meter, a garden-variety $20 job, but it seems to
be working fine.

Thanks all,

Don

===============
Don Rahmlow
Ramfish Golf
www.ramfish.com
===============


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