[sdiy] yard sale find

[Don Tillman]

   > From: "Theo" <t.hogers at home.nl>
   > Date: Tue, 30 Jul 2002 13:43:06 +0200
   > 
   > From: harry <harrybissell at prodigy.net>
   > 
   > > Theo wrote:
   > >
   > > > As long you don't work with high voltages you don't need a
   > > > 10x probe.
   > >
   > > Arrgh. BIGGEST mistake you can make.  The purpose of the 10X
   > > probe is almost NEVER to allow "higher voltages"...  its to
   > > allow the probe to load the circuit with 10X the resistance
   > > (1/10 of the load).
   >
   > Now that I have already proven my stupidity, I may as well go on
   > and ask a stupid question.  Using FET inputs one can get
   > extremely high input impedances, so why use scopes a "low" input
   > impedance of only 1M ohm and not 10M or 100M?

The cable capacitance effects would swamp out the 10M ohm impedance.

  -- Don

-- 
Don Tillman
Palo Alto, California, USA
don at till.com
http://www.till.com