Maker Pro
Maker Pro

A relatively unimportant announcement...

J

James Meyer

Jan 1, 1970
0
James Meyer wrote:
(snip)

I played around with the simulator, last night, and was able to get a
voltage gain of about 2 with the 2N3904 common emitter at 40 MHz with
an source impedance about twice the collector resistor. Pretty lame.
But I did a bit better (more than 4) with a cascode arrangement. I
may try to see what I can do with an emitter follower on input and
output (4 transistors, total). The low input impedance of the common
emitter stage at 40 MHz is what really bites when you are trying to
get both voltage and current gain, unless you can tune the capacitance
out with inductance, but then you get a narrow band amplifier and a
big tendency to oscillate.

(snip)

The simulation is unrealistic in another way too. The input signal
generator with its 50 ohm internal impedance is coupled directly to the input
transistor's base with a cap. That supplies the base with unreasonably high
currents. In the real world where the antenna supplies current to the LC
network, the relatively low input impedance will suck up all the current leaving
precious little voltage at the input.

Jim
 
F

Fred Bloggs

Jan 1, 1970
0
John said:
James Meyer wrote:
(snip)



I played around with the simulator, last night, and was able to get a
voltage gain of about 2 with the 2N3904 common emitter at 40 MHz with
an source impedance about twice the collector resistor. Pretty lame.
But I did a bit better (more than 4) with a cascode arrangement. I
may try to see what I can do with an emitter follower on input and
output (4 transistors, total). The low input impedance of the common
emitter stage at 40 MHz is what really bites when you are trying to
get both voltage and current gain, unless you can tune the capacitance
out with inductance, but then you get a narrow band amplifier and a
big tendency to oscillate.

(snip)

He does in fact want a narrowband gain- how else is he going to
discriminate which RF frequency is driving the meter?
 
J

John Popelish

Jan 1, 1970
0
Paul said:
On Fri, 26 Dec 2003 08:37:08 -0800, John Larkin


GBW? What's that?

Gain BandWidth product. A common emitter amplifier has a gain
bandwidth product. Lower the frequency (bandwidth) and you can have
more gain. I found from experiment that a stage like you have been
playing with has a gain bandwidth product of about 80 million. This
allows a gain of 2 at 40 MHz.
 
P

Paul Burridge

Jan 1, 1970
0
I you will now kindly un-nail my ass from the wall, I can go about my
business.

Not yet, John. I have to finish the real circuit.
 
P

Paul Burridge

Jan 1, 1970
0
Paul, Please explain to the group *how* this waveform influences a
meter?

I delegate that to Kevin. I merely have to establish that the circuit
works as advertised. ;-)
 
J

Jim Thompson

Jan 1, 1970
0
Not yet, John. I have to finish the real circuit.

Your pomposity is under-whelming.

You need to thoroughly study, AND understand, capacitors, diodes, and,
from what I can see, I don't think you even understand resistors.

And you're certainly IGNORANT about transistors.

Have a good day ;-)

...Jim Thompson
 
P

Paul Burridge

Jan 1, 1970
0
Your pomposity is under-whelming.

Thank you.
You need to thoroughly study, AND understand, capacitors, diodes, and,
from what I can see, I don't think you even understand resistors.

I think it's a bit unreasonable accusing me of being *that* stupid.
What precisely leads you to think I can't even understand resistors?
And you're certainly IGNORANT about transistors.

There's a lot I still don't know, I fully ackowledge that.
Have a good day ;-)

And the same to you.
 
J

Jim Thompson

Jan 1, 1970
0
Thank you.


I think it's a bit unreasonable accusing me of being *that* stupid.
What precisely leads you to think I can't even understand resistors?


There's a lot I still don't know, I fully ackowledge that.


And the same to you.

Don't jump ahead. Enlighten me with some FUNDAMENTALS about
capacitors and diodes. Then we'll fret over resistors.

...Jim Thompson
 
P

Paul Burridge

Jan 1, 1970
0
Don't jump ahead. Enlighten me with some FUNDAMENTALS about
capacitors and diodes. Then we'll fret over resistors.

Okay, I'm not sure if you're serious about this but I'll bite.
Capacitors - ideal ones anyway - impede the flow of AC current in
inverse proportion to their value for a a given frequency and block DC
(except for a small leakage current). Diodes conduct mostly in one
direction only when forwardly-biased after their energy hill/barrier
height potential is overcome. Will that suffice for the sake of
brevity? Your question wasn't very specific.
 
J

Jim Thompson

Jan 1, 1970
0
Okay, I'm not sure if you're serious about this but I'll bite.
Capacitors - ideal ones anyway - impede the flow of AC current in
inverse proportion to their value for a a given frequency and block DC
(except for a small leakage current). Diodes conduct mostly in one
direction only when forwardly-biased after their energy hill/barrier
height potential is overcome. Will that suffice for the sake of
brevity? Your question wasn't very specific.

That will suffice... you actually defined *non-ideal* caps and diodes.

NOW, why won't your capacitively-coupled rectifier produce the *DC*
component of current which your meter needs to produce an indication?

...Jim Thompson
 
P

Paul Burridge

Jan 1, 1970
0
NOW, why won't your capacitively-coupled rectifier produce the *DC*
component of current which your meter needs to produce an indication?

Because the capacitor will block it, being in series with the diode
and meter, ergo no DC to speak of through that part of the circuit.
D'oh! I can't believe I came up with this hair-brained idea in the
first place! :-( Thank God I don't have any reputation in the
electronics field to lose. Happy now?
 
J

Jim Thompson

Jan 1, 1970
0
Because the capacitor will block it, being in series with the diode
and meter, ergo no DC to speak of through that part of the circuit.
D'oh! I can't believe I came up with this hair-brained idea in the
first place! :-( Thank God I don't have any reputation in the
electronics field to lose. Happy now?

No, I would have rather you acted as a student in learning-mode
instead of the belligerent stance you took.

...Jim Thompson
 
P

Paul Burridge

Jan 1, 1970
0
No, I would have rather you acted as a student in learning-mode
instead of the belligerent stance you took.

I suppose the problem is I'm simply just not used to being wrong -
except in this particular field where I manage an all-too-conspicuous
degree of it.
Can I go to bed now? I'm depressed. ;-)
 
J

Jim Thompson

Jan 1, 1970
0
I suppose the problem is I'm simply just not used to being wrong -
except in this particular field where I manage an all-too-conspicuous
degree of it.
Can I go to bed now? I'm depressed. ;-)

Being wrong is something you have to get used to. I figure I've been
wrong *at least* 10X the number of times I've been right. Engineering
is about being able to wad up the piece of paper and start over...
without being depressed.

The only problem that ever caused me was the wife getting ticked
because I just threw the paper wads over my shoulder into the dining
room ;-)

...Jim Thompson
 
M

Michael A. Terrell

Jan 1, 1970
0
Jim said:
Being wrong is something you have to get used to. I figure I've been
wrong *at least* 10X the number of times I've been right. Engineering
is about being able to wad up the piece of paper and start over...
without being depressed.

The only problem that ever caused me was the wife getting ticked
because I just threw the paper wads over my shoulder into the dining
room ;-)

...Jim Thompson

Its a good thing your computer has a delete key. It would be
hazardous for you to toss your computer across your shoulder. ;-)


--
Merry Christmas!

Take care, and God bless.
Michael A. Terrell
Central Florida
 
B

Bill Garber

Jan 1, 1970
0
message : Jim Thompson wrote:
: >
: > Being wrong is something you have to get used to. I figure
I've been
: > wrong *at least* 10X the number of times I've been right.
Engineering
: > is about being able to wad up the piece of paper and start
over...
: > without being depressed.
: >
: > The only problem that ever caused me was the wife getting
ticked
: > because I just threw the paper wads over my shoulder into the
dining
: > room ;-)
: >
: > ...Jim Thompson
:
: Its a good thing your computer has a delete key. It would be
: hazardous for you to toss your computer across your shoulder.
;-)

That's good point, Jim. Now please tell me what to
do with this stack of schematics I have drawn and
never got around to doing anything with yet. There
must be 3-4 dozen of them from simple LED flashers
to full blown interfaces. ;-)

Bill @ GarberStreet Enterprizez };-)
Web Site - http://garberstreet.netfirms.com
Email - [email protected]
Remove - SPAM and X to contact me
 
M

Mark Jones

Jan 1, 1970
0
In news:[email protected] (Bill Garber):
That's good point, Jim. Now please tell me what to
do with this stack of schematics I have drawn and
never got around to doing anything with yet. There
must be 3-4 dozen of them from simple LED flashers
to full blown interfaces. ;-)

Bill @ GarberStreet Enterprizez };-)


You could always post them here, using some obscure title like "STD's" or
something. :)
 
B

Bill Garber

Jan 1, 1970
0
"Mark Jones" <127.0.0.1> wrote in message
: In (Bill Garber):
: > message : >> Jim Thompson wrote:
: >>>
: >>> Being wrong is something you have to get used to. I figure
I've been
: >>> wrong *at least* 10X the number of times I've been right.
Engineering
: >>> is about being able to wad up the piece of paper and start
over...
: >>> without being depressed.
: >>>
: >>> The only problem that ever caused me was the wife getting
ticked
: >>> because I just threw the paper wads over my shoulder into
the dining
: >>> room ;-)
: >>>
: >>> ...Jim Thompson
: >>
: >> Its a good thing your computer has a delete key. It would
be
: >> hazardous for you to toss your computer across your
shoulder. ;-)
: >
: > That's good point, Jim. Now please tell me what to
: > do with this stack of schematics I have drawn and
: > never got around to doing anything with yet. There
: > must be 3-4 dozen of them from simple LED flashers
: > to full blown interfaces. ;-)
: >
: > Bill @ GarberStreet Enterprizez };-)
:
:
: You could always post them here, using some obscure title like
"STD's" or
: something. :)

I could do that. How many of you guys have Apple IIs? ;-)
Quite a few of them are for those.

Bill @ GarberStreet Enterprizez };-)
Web Site - http://garberstreet.netfirms.com
Email - [email protected]
Remove - SPAM and X to contact me
 
J

Jim Thompson

Jan 1, 1970
0
message : Jim Thompson wrote:
: >
: > Being wrong is something you have to get used to. I figure
I've been
: > wrong *at least* 10X the number of times I've been right.
Engineering
: > is about being able to wad up the piece of paper and start
over...
: > without being depressed.
: >
: > The only problem that ever caused me was the wife getting
ticked
: > because I just threw the paper wads over my shoulder into the
dining
: > room ;-)
: >
: > ...Jim Thompson
:
: Its a good thing your computer has a delete key. It would be
: hazardous for you to toss your computer across your shoulder.
;-)

That's good point, Jim. Now please tell me what to
do with this stack of schematics I have drawn and
never got around to doing anything with yet. There
must be 3-4 dozen of them from simple LED flashers
to full blown interfaces. ;-)

Bill @ GarberStreet Enterprizez };-)
Web Site - http://garberstreet.netfirms.com
Email - [email protected]
Remove - SPAM and X to contact me



---
This email ain't infected, dude!

Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.544 / Virus Database: 338 - Release Date: 11/25/03

I have a *very* large hard-drive on my simulation machine ;-)

...Jim Thompson
 
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