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Sun May 18 21:57:18 EDT 2014

Capacitance

The speed of the 2N7000 with 10k gate resistor surprised me (3.5uS
charge discharge time for a 45nF cap on 3.3V).

( EDIT: this was probably due to a 22k pull down resistor I missed,
setting V_GS too low. )

What's the gate capacitance? 20pF typical, 50pF max.  t_RC = (* 10e3
20e-12) 0.2uS so that's not it.  Maybe cap of breadboard[1]?  10pF
rule-of-thumb according to Dave, rule of thumb don't do >1MHz on
breadboard.  After measuring it's 2.5pF between strips and 20pF on the
power strips.

[1] http://www.eevblog.com/2014/01/15/eevblog-568-solderless-breadboard-capacitance/



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