From: "Michael A. Terrell"
Subject: Re: how to master electronics, use of transistor, op amp...?
Date: Fri, 01 Nov 2002 23:25:51 -0500
Organization: Have you seen my bench? No, really! Where is it?
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Winfield Hill wrote:
> Winfield wrote...
> > Wafer wrote...
> >> Please don't confuse skill with talent. Skill is acquired over time,
> >> and involves much work and effort, while talent is there from the very
> >> beginning. However, lets not get tied up with semantics. I suppose I
> >> should have also pointed out my obsession with electronics. ...
> >> [ snip ]
> >> I would have to say that since Stephen William Hawking concerns
> >> himself with theoretical physics and such, he may not be an appropriate
> >> example of someone who would (or could) design an electronic circuit in
> >> his head. Besides, it's not a matter of mathematics, or some enormous
> >> number of calculations. Rather it is something which I actually find
> >> difficult to put into words. I just do it. ...
> > I find it difficult to design electronic circuits without extensive
> > calculations, maybe not always written entirely on paper, but either
> > performed in my head or using an ever-present pocket calculator, and
> > with the results appearing on paper in one growing schematic drawing,
> > or in a set of drawings representing different possible approaches.
> > So, it's very hard for me to comprehend designing viable circuits
> > without any schematic at all, either on paper or in computer file.
> > Perhaps you'd like to try your hand at a design I'm completing now,
> > a quiet transresistance preamp (current-to-voltage) that presents
> > 5pA current steps as 0.5V voltage-step outputs with a response time
> > of 10us or better, with 100pF node capacitance. We'll have to also
> > assume you already know the component's parasitic properties to make
> > the appropriate selections and modify the design accordingly, right?
> > If you quickly finish the design, you'll have time to design a test
> > fixture to verify its impressive performance.
> > To my mind this type of relatively-simple design cannot be achieved
> > entirely in one's head, so it should be a good test for your skill.
> > Remember, be honest now, no paper or computer allowed for this test.
> > :-)
> Oh, wafer, a few other circuit specs for this test. My circuit has
> only two 8-pin ICs, makes measurements to 10fA without requiring any
> adjustments or calibrations, and drives a 50-foot cable. The two ICs
> are inexpensive parts that have been available for several years.
> - Win
You're going to make him sweat a little, aren't you, Win? :)
Michael A. Terrell