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Subject: Re: how to master electronics, use of transistor, op amp...?
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Date: Sat, 02 Nov 2002 15:29:26 GMT
NNTP-Posting-Date: Sat, 02 Nov 2002 10:29:26 EST
Organization: Road Runner
Kevin Aylward wrote:
> "Wafer" wrote in message
>>Winfield Hill wrote:
>>>>> Please don't confuse skill with talent. Skill is acquired over
>>>>>and involves much work and effort, while talent is there from the
>>>>>beginning. However, lets not get tied up with semantics. I suppose
>>>>>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
>>>>>example of someone who would (or could) design an electronic
> circuit in
>>>>>his head. Besides, it's not a matter of mathematics, or some
>>>>>number of calculations. Rather it is something which I actually
>>>>>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
>>>>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
>>> adjustments or calibrations, and drives a 50-foot cable. The two
>>> are inexpensive parts that have been available for several years.
>> Well, this sounds like an interesting little circuit. I actually
>>don't usually approach a design from this prospective either. Again,
>>self taught, and although it has obvious advantages to me, it
>>means that my approach is to solve a particular need. What this
>>requires is some understanding of the purpose of the circuit, not in
>>turms of specs on paper, but in the real world application. Something
>>like: here is a signal that need to get through a 50FT. cable with no
>>more than so much loss. The signal can't see an impedance of less than
>>x, and must arrive at the other end with as little distortion as
>>possible, etc, etc.
> The reality is, is that without a spec, you don't really have *design*.
>> You see, I simply skip most of the calculations and just put
>>together something that would probably have at least fair performance,
>>then tweak the thing as needed.
>>In the case of your circuit
>>requirements, I can see that simply using a standard breadboard would
>>screw up the whole thing. Stray capacitances alone would see to that.
>> In any case, this entire discussion is not about my skill, talent,
>>or anything else. It's not about any one person at all. The thread was
>>started by someone asking how one goes about "mastering electronics",
>>and asked for others to share experiences. That's what I did, and if I
>>knew it would turn into a contest, I would not have responded as I
> First, learn to reply at the end of the post, not the top.!!!!!!
> The issue here, is that the description of how you claim to "design"
> circuits goes against, I would say, 99% of what professional design
> engineers actually do. With all due respect, its not really believable.
> That's why the flack. You've got to accept that there are quite a few
> here who have degrees *and* have many, many, years experience, and know
> how things are usually done in commercial companies that you cant
> bullshit with. If you claim things that are *known* to be dubious, you
> going to get hit on.
> Kevin Aylward
> SuperSpice, a very affordable Mixed-Mode
> Windows Simulator with Schematic Capture,
> Waveform Display, FFT's and Filter Design.
OK, so I'm replying at the end. I know where you guys are coming
from, believe me. I have had to deal with this constantly, and it always
causes arguments. That certainly was NOT my intent, nor am I trying to
make any incredible claims. I just put in my two cents on the original
post, and the entire thread has gone completely off-track. I just have a
different prospective than most, but that doesn't make me wrong, just
To illustrate, until not all that long ago, you needed A/D and D/A
conversion, along with the memory chip and so forth, to make a circuit
capable of audio recording and playback. Now, it is done within a single
chip, and requires no digital conversion of any kind. The analog samples
are written directly to the nonvolatile memory. Simply sequencing
through the addresses at the same rate as recorded reproduces the audio.
The chips are less than 10 bucks and are available in versions capable
of 4 minutes of record time (the last I checked). The fact is, it could
have been done much earlier, but nobody thought of it. That's really
what I'm getting at here. I see things from a different prospective, so
I end up with different solutions than others. Without the "formal
training", it's hard for me to explain things in "standard" terms, and
some of those terms actually make little sense to me, which results in
conflict. You guys prove it on paper first, where I prove it by building
the thing. Maybe it comes from the fact that as a kid I always took
apart my toys to see what made them tick, resulting in a reverse
engineering method: Start with what works, and explain it later (if
ever). When I need a circuit for something, I reach for a breadboard and
start plugging in parts. I know what I'm after, and I (usually) know
where to start. Over time, I've come up with enough stuff that works,
that it makes each project go that much easier, and turn out that much
For instance, if I ask you to come up with a simple circuit that
would toggle power to a load on and off with each press of a momentary
switch, but draw no current in the off state, what would you do? I would
bet that your circuit would be nothing like mine.