Re: kids these days

On 2024-09-30 17:24, john larkin wrote:

On Mon, 30 Sep 2024 11:13:56 +0100, Cursitor Doom <cd@notformail.com>
wrote:
 

On Mon, 30 Sep 2024 05:15:02 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
>

On a sunny day (Sun, 29 Sep 2024 10:36:26 -0700) it happened john larkin
<JL@gct.com> wrote in <kb3jfjpejs47hqjd00fis20eog8de19ae8@4ax.com>:
>

I wouldn't hire someone who complicates a simple question into
paralysis.
>
>
I draw a 10 volt battery connected to two resistors, 9K in series with 1K.

>
The problem there is 'draw', no reality.
The battery will have an internal resistance, maybe discharged too.
>

What's the voltage across the 1K?

>
>
>

I hired a 3-month intern a month ago who failed the test. He said 9
volts. I hired him anyway and fired him as an intern on Friday. He's
full time now. He's mostly a software engineer. I'm teaching him basic
electronics now.

>
Well, that is OK.
But needs experimenting, building circuits, else all vaporware.
Same with software, write it, test it, else just imagination...
It may not be / work for everybody..
Some run for US precedent..
When I have to believe the crap trump puts out these days (about Iran for example)
4 sure (or maybe even 00 sure <where 00 is the symbol for infinite> ) we will have
WW3 no matter who is winning the electtions.
>
>

I dream of some day finding a kid who gets the voltage divider right
and has something intelligent so say about the next test, an NPN
emitter follower.

>
Ge or Si?

>
John mentioned a Vb of 0.6V so the 'student' is expected to know it's
silicon. And of course, it's a Vbe of 0.6V and that distinction seems
to trip up a lot of young folks, it seems. The Vb is 5. Once they get
that straight, the rest of it falls into place easily enough. Should
take < 30s for someone to figure out - and hopefully <<!

 No, I said that one EE grad claimed that Vb (not Vbe) would be 0.6
volts to ground.
 Can anyone here say about what the base and emitter voltages actually
are? Collector current?
 +10 supply, two 10Ks making a divider into the base, 1K emitter to
ground, typical small silicon NPN.
 Extra credit: anything else to say?
 

Think a resistor of 1K times hFE in parallel to the lower base divider resistor and recalculate for a better approximation.
Or estimate Ib from Ie/hFE and use the Thevenin of the base resistors to correct the base drive voltage.
Or use LTspice...
Arie