Meter schematic - fsm3.jpg (0/1)

[Fred Bloggs]

On Sun, 28 Dec 2003 16:12:39 -0700, Jim Thompson




[snip]


If we examine the circuit that's the driving force behind this thread,
it's easy to see that the circuit topology has many flaws.
No amount of value tweeking in the simulation will make the topology
feasible...period! The damned thing needs to be DESIGNED!!!
The damned thing doesn't even have a design spec, so it
can't be designed. And the OP has steadfastly resisted most
suggestions.

I haven't interviewed an engineer in a decade, but even back then
most of them didn't have a clue how to design anything. They just
stuffed numbers into a simulation program and hacked on it 'till
it looked good to them. Ask them to take pencil and paper to draw
a schematic for a one-transistor amplifier and they didn't have
any idea how to estimate it's performance. They didn't get hired!

mike

Amen!

Back in the days when I hired engineers right-out-of-school I used to
test them with a simple one-transistor, two-diode, three-resistor
circuit.

100% couldn't solve it.

95% didn't even know how to approach the problem :-(

I hired the few who could figure out where to begin.

(Only paper and pencil were allowed

(I'll post it later.)

...Jim Thompson


I like this one:

+10v
|
|
c
+5v---------b
e
|
|
1k
|
|
gnd

Question: what is the collector voltage (yes, they miss this one!)
what is base voltage? (ditto!)
what is emitter voltage?
what are the currents?
any other comments?

This turns fatheads into jelly.

John

That's California for you- P-A-T-H-E-T-I-C!!!!!!!!!!!!

What's the state got to do with it? I get applicants from all over the
world, and I first started using this test when I lived in New
Orleans.

Where do you live? How does your electronics industry compare to
California's? Extra credit question: why?


John

Are you telling me that you pay applicants of this caliber to travel
long distance for an interview? It would be more economical to read
those resumes more closely. Most people I ever interviewed with were
garbage- and I'm talking about when I was the interviewee- took an
immediate dislike to them- no thnx- will pick up road litter first.

 

[Jim Thompson]

John Larkin wrote: [snip]

Where do you live? How does your electronics industry compare to
California's? Extra credit question: why?


John

Are you telling me that you pay applicants of this caliber to travel
long distance for an interview? It would be more economical to read
those resumes more closely. Most people I ever interviewed with were
garbage- and I'm talking about when I was the interviewee- took an
immediate dislike to them- no thnx- will pick up road litter first.

So now we know what Fred does for a living ?

...Jim Thompson

 

[Fred Bloggs]

John Larkin wrote:
[snip]

Where do you live? How does your electronics industry compare to
California's? Extra credit question: why?


John

Are you telling me that you pay applicants of this caliber to travel
long distance for an interview? It would be more economical to read
those resumes more closely. Most people I ever interviewed with were
garbage- and I'm talking about when I was the interviewee- took an
immediate dislike to them- no thnx- will pick up road litter first.

So now we know what Fred does for a living ?

...Jim Thompson

LOL- nearly I sure don't get paid for any electronics abilities- just
a pastime

 

[John Larkin]

No answers, I see.

Are you telling me that you pay applicants of this caliber to travel
long distance for an interview?

Pay applicants travel expenses? Wow, that's really funny! If I like
them, I might buy them lunch.

It would be more economical to read
those resumes more closely.

Little circuit questions are reality checks on resumes. Lots of resume
claims are bogus.

took an immediate dislike to them-

Why am I not surprised?

John

 

[Fred Bloggs]

No answers, I see.

My initial exposure to electronics was in the geographic area that sent
all those people west to found California's electronics industry

Pay applicants travel expenses? Wow, that's really funny! If I like
them, I might buy them lunch.

Okay- that's a giveaway there- unless there's something you're not
telling us about your company- anyone who would fly thousands of miles
for an interview is desperate.

Little circuit questions are reality checks on resumes. Lots of resume
claims are bogus.

That's the truth.

 

[John Popelish]

Are you telling me that you pay applicants of this caliber to travel
long distance for an interview? It would be more economical to read
those resumes more closely. Most people I ever interviewed with were
garbage- and I'm talking about when I was the interviewee- took an
immediate dislike to them- no thnx- will pick up road litter first.

I believe you. Taking an immediate dislike to people is a special
talent you have demonstrated, here. I am amazed at the energy you
sometimes invest in this process. Happily, it is obviously not your
only talent. I am pretty slow to develop dislike, but have gotten
there a few times. I give people lots of benefit of the doubt in case
they are having a bad day, week or month, but eventually, I can reach
the conclusion that they are just energy suckage.

The few times I interviewed for a job, I dressed like a hippy as a way
to test prospective employers who might be somewhat like you in this
'immediate dislike' regard. The results were faster than John
Larkins simple circuit. Either they hated me, or they at least
pretended to try to find out something else about me. I almost got
thrown out of one place. But first, I got to talk with the man who
actually needed some engineering help, and he voted to take me, over
his boss's (the one who wanted me thrown into the street and who
dressed like an undertaker) objection. As long as the guy who hired
me was around, I very much enjoyed working with his team. After he
left the company, I lasted a couple months before I couldn't stand to
work there. I turned in my resignation before even looking for a
replacement. I would rather have eaten bark than put up with the
general attitude, there. It is amazing how one person can create a
life raft of positive feeling in a sea of sharks.

Skill makes it possible to do the work, but personalities of those you
work with may be what gets you out of bed in the morning (or makes you
want to hide under the covers).

 

[John Larkin]

Okay- that's a giveaway there- unless there's something you're not
telling us about your company- anyone who would fly thousands of miles
for an interview is desperate.

Where and when I am now, a couple of ads in the SF Chronicle (rotten
rag!) and the SJ Mercury News (an excellent newspaper, actually) will
ship in a couple of hundred resumes from people who are within commute
distance. I really don't want the responsibility (not to mention the
expense) of moving somebody hundreds or thousands of miles to work for
me. Interview all you want, but you never really know about a person
until you work with them; if it doesn't work out, I'd rather not be
responsible for transplanting somebody to a new city and then
stranding them here without a job.

Out of those couple-hundred resumes, we're lucky to find one or two
real electronics designers. Everybody else is a Microsoft-certified CS
jock or something.

John

 

[John Crighton]

Skill makes it possible to do the work, but personalities of those you
work with may be what gets you out of bed in the morning (or makes you
want to hide under the covers).

Yes, you are spot on there John P. I know what you mean.
Regards,
John C

 

[mike]

mike wrote:




We are in serious danger of arguing over definitions here so I won't excpet
to say that to me all the above are part of the design process so I would
rewrite you list as:

Initial design, evaluate (by whatever means), modify design, re-evalute,
repeat as necessary.

Ian

I think we're in heated agreement. My objection is that too many
"designers" start plugging numbers into a simulator without even a clue
as to how many stages of amplification they're likely to need. They end
up with a design that looks good in the simulator, but can't be
sustained in production.
mike

--
Return address is VALID.
Bunch of stuff For Sale and Wanted at the link below.
Toshiba & Compaq LiIon Batteries, Test Equipment
Honda CB-125S $800 in PDX
TEK Sampling Sweep Plugin and RM564
Tek 2465 $800, ham radio, 30pS pulser
Tektronix Concept Books, spot welding head...
http://www.geocities.com/SiliconValley/Monitor/4710/

 

[Fred Bloggs]

Fred Bloggs wrote:




I believe you. Taking an immediate dislike to people is a special
talent you have demonstrated, here. I am amazed at the energy you
sometimes invest in this process. Happily, it is obviously not your
only talent. I am pretty slow to develop dislike, but have gotten
there a few times. I give people lots of benefit of the doubt in case
they are having a bad day, week or month, but eventually, I can reach
the conclusion that they are just energy suckage.

The few times I interviewed for a job, I dressed like a hippy as a way
to test prospective employers who might be somewhat like you in this
'immediate dislike' regard. The results were faster than John
Larkins simple circuit. Either they hated me, or they at least
pretended to try to find out something else about me. I almost got
thrown out of one place. But first, I got to talk with the man who
actually needed some engineering help, and he voted to take me, over
his boss's (the one who wanted me thrown into the street and who
dressed like an undertaker) objection. As long as the guy who hired
me was around, I very much enjoyed working with his team. After he
left the company, I lasted a couple months before I couldn't stand to
work there. I turned in my resignation before even looking for a
replacement. I would rather have eaten bark than put up with the
general attitude, there. It is amazing how one person can create a
life raft of positive feeling in a sea of sharks.

Skill makes it possible to do the work, but personalities of those you
work with may be what gets you out of bed in the morning (or makes you
want to hide under the covers).

The manufacturing sector is like that-you might want to find a different
part of the industry- and try to conform a little better with your
appearance.

 

[John Popelish]

John Popelish wrote: (snip)


The manufacturing sector is like that-you might want to find a different
part of the industry- and try to conform a little better with your
appearance.

Why should I conform? And I have no complaint about the part of the
manufacturing sector I now work at. The problems I had were with a
specific group at one company.

At the plant where I contract, now, I had a big part in breaking the
'every salaried parson must wear a neck tie' mold. I got hard looks
for wearing casual cloths to work but as I said, I was an engineering
contractor, so all they could do was grouse (or fire me). One manager
refused to speak to me for years. Then, one day, the young plant
manager sat down to have lunch with me, without wearing his tie. All
over the cafeteria, I saw mouths hanging open, forks full, but
forgotten. The next day (and ever since), not one tie was seen
anywhere in the plant, except on visitors, though most of the old
timers kept one in the deck for years, in case the rules of conformity
changed, again.

Since then I got a motorcycle, switched from tee shirts and corduroy
pants to flannel plaid shirts, blue jeans and motor cycle boots (with
the jeans bloused into the boots), since I ride the bike to work any
time it is not pouring rain or snowing. Until recently riding a
motorcycle to work was also severely frowned upon for salaried
personnel. Since I have been there, acceptance of personal taste has
improved a whole lot. Did I tell you that I also sport a full beard.
My shoulder length hair had to go when I started riding, because it
got tangled in the slip stream.

I like to think that I made it easier for anyone to be accepted at
that plant as they are, because at the very least they weren't as
strange as I was. I have also gone out of my way to always treat
everyone with exactly the same courtesy, regardless of their rank or
position. I have sort of become the plant mascot, even though I have
been always worked there as a contractor. People ask me why I am so
happy that I whistle while I walk, and I say it is because they let me
play with their factory.

 

[Tom Del Rosso]

In John Popelish typed:

Since then I got a motorcycle, switched from tee shirts and corduroy
pants to flannel plaid shirts, blue jeans and motor cycle boots (with
the jeans bloused into the boots), since I ride the bike to work any
time it is not pouring rain or snowing. Until recently riding a
motorcycle to work was also severely frowned upon for salaried
personnel. Since I have been there, acceptance of personal taste has
improved a whole lot. Did I tell you that I also sport a full beard.
My shoulder length hair had to go when I started riding, because it
got tangled in the slip stream.

There's a movie on the Flix channel this week: "Some Kind of a Nut",
with Dick van Dyke. Not a great movie, but it's about somebody like
you.

 

[Tom Del Rosso]

In Jim Thompson typed:

Nope! You "performed" precisely to expectation ;-)

What about your interview test circuit? Did you post it already?

 

[John Popelish]

I probably should not post a design this late at night, but here is my
attempt at the field strength meter. The inductor on the input is a
stiff few turn coil of largish diameter to act as an antenna, while
the other three are 3 pieces of 30 gauge wire wrap wire wound,
together through a two hole core, like those used for baluns. At
least this shows you can get some voltage gain out of two slow
transistors. I set the AC input to 1 volt, so the responses can be
displayed directly as voltage gain.

The sensitivity is no where near 50 uv full scale, but that is way too
sensitive for use near a transmitter, in my opinion. It pegs at about
20 mv but should show a noticeable deflection at less than 1 mv. The
sensitivity could be higher by leaving out the resistor in series with
the meter (R2), but then it is a lot less linear. I'll post the
schematic without comment on a.b.s.e.

Version 4
SHEET 1 948 680
WIRE 48 464 80 464
WIRE 144 512 144 560
WIRE 144 416 144 256
WIRE 240 272 432 272
WIRE 240 272 240 208
WIRE -240 -64 -240 -32
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WIRE 48 240 48 208
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SYMBOL npn 80 160 R0
SYMATTR InstName Q2
SYMATTR Value 2N3904
SYMBOL voltage -16 352 R0
WINDOW 123 -283 79 Left 0
WINDOW 39 -291 112 Left 0
WINDOW 0 -39 2 Left 0
WINDOW 3 -328 47 Left 0
SYMATTR Value2 AC 1 0
SYMATTR SpiceLine Rser=0
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SYMATTR Value SINE(0 1m 40e6)
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SYMATTR Value 2N3906
SYMBOL voltage -144 -64 R90
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SYMATTR Value 9
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SYMATTR Value 47k
SYMBOL res -112 224 R0
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SYMATTR Value 20k
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SYMATTR Value 1n
SYMBOL cap 32 240 R0
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SYMATTR Value 1n
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SYMATTR Value 20k
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SYMATTR Value 1n
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SYMATTR Value 1n
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SYMATTR Value 470n
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SYMATTR Type diode
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SYMATTR Value 150k
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TEXT 288 496 Left 0 !;op
TEXT 288 424 Left 0 !;ac dec 100 1e6 100e6
TEXT 288 464 Left 0 !.tran 0 2u 0
TEXT 168 -96 Left 0 !K1 L1 L5 L6 .7

 

[Paul Burridge]

I probably should not post a design this late at night, but here is my
attempt at the field strength meter. The inductor on the input is a
stiff few turn coil of largish diameter to act as an antenna, while
the other three are 3 pieces of 30 gauge wire wrap wire wound,
together through a two hole core, like those used for baluns. At
least this shows you can get some voltage gain out of two slow
transistors. I set the AC input to 1 volt, so the responses can be
displayed directly as voltage gain.

The sensitivity is no where near 50 uv full scale, but that is way too
sensitive for use near a transmitter, in my opinion. It pegs at about
20 mv but should show a noticeable deflection at less than 1 mv. The
sensitivity could be higher by leaving out the resistor in series with
the meter (R2), but then it is a lot less linear. I'll post the
schematic without comment on a.b.s.e.

Thanks, John. Looks like people my me who want to build a fsm will not
be spoiled for choice!
I hope newbies reading this group will realise this apparent obsession
with fsms is not representative of the normal trafffic on the group
(which constitute personal insults, politics, recipe exchanging and
weather reports).

 

[Paul Burridge]

Why should I conform? And I have no complaint about the part of the
manufacturing sector I now work at. The problems I had were with a
specific group at one company.

Some of the brightest computer guys I know dress just like you, John
and they're not just very hard-working and reliable; they're very
personable, too. I guess any prospective employer who turns you away
on the grounds of how you look is simply concerned about how his
company's customers will react to having someone dressed like you
working for his firm. It's more of an *image* thing than a person
rejection. I think that's the real problem why a lot you guys find it
hard to get hired.

 

[Paul Burridge]

In Jim Thompson typed:

What about your interview test circuit? Did you post it already?

Save it for a couple of days, Jim. I'm on the mend and promise to make
a proper effort on the next one!

 

[Jim Thompson]

In Jim Thompson typed:

What about your interview test circuit? Did you post it already?

Not yet.

...Jim Thompson

 

[Spehro Pefhany]

Some of the brightest computer guys I know dress just like you, John
and they're not just very hard-working and reliable; they're very
personable, too. I guess any prospective employer who turns you away
on the grounds of how you look is simply concerned about how his
company's customers will react to having someone dressed like you
working for his firm. It's more of an *image* thing than a person
rejection. I think that's the real problem why a lot you guys find it
hard to get hired.

One of the top technical guys for a major telecom company showed up at
a seminar wearing some kind of long skirt and other totally bizzarre
articles of clothing (and maybe piercings, I didn't inspect closely).
My first thought was that he must be really, really good to get away
with it. Perhaps it's more of a studied approach to self-promotion
than some pointless non-conformity exercise.


Best regards,
Spehro Pefhany

 

[YD]

Silicon, NPN

Beta = 99

IS = 8.7282fA

kT/q = 26mV

Ignore current crowding, leakage and Early effect.

Accurate description of how you got your answers, NO SWAGs.

Okay, substituting your values in the E-M equation:

Ic=8.7282^-15 [exp (0.65/26^-3)-1]

gives: Ic=22.4mA

Ib=Ic/99=0.226mA



Do I get to keep my ass?

You forgot about the 1 k resistor. Assuming it's a short to ground and
power supplies without current limiting the solution turns out to be
Vc=10V, Vb=5V, Ib=0A, Ic=0A shortly after turn-on.

- YD.