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John Larkin John Larkin is offline
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I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

but it occurred to me that it might also make a nice headphone amp...

ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG


Audio tends to be nonsense, but at least the audio guys have fun
playing with circuits, whether they make a lot of sense or not.

John



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Fred Bloggs[_2_] Fred Bloggs[_2_] is offline
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Default another bizarre audio circuit

On Mar 2, 11:40*am, John Larkin
wrote:
I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

but it occurred to me that it might also make a nice headphone amp...

ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG

Audio tends to be nonsense, but at least the audio guys have fun
playing with circuits, whether they make a lot of sense or not.

John


Bizarre??? Just a standard buffered input CE with negative feedback DC
bias to stabilize the operating point against Vbe and reverse leakage
collector current change with temperature- a textbook circuit...
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Bitrex Bitrex is offline
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Default another bizarre audio circuit

On 3/2/2011 11:40 AM, John Larkin wrote:


I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

but it occurred to me that it might also make a nice headphone amp...

ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG


Neat, like a parafeed amplifier. The choke will have to be pretty big
for audio frequencies...

I can think of a modification that would give more gain for the negative
feedback to "work" with: change the input transistor to a JFET, get rid
of the capacitor and extra resistor in the bias stabilization circuit,
and just stick a resistor in the emitter lead of the output transistor.
Then, move the load resistor of the first stage down and connect an
NPN transistor with a current limiting resistor to the output between
that load resistor and the power supply. If I've figured things out
correctly you then have a gyrator load for the first stage. The bias
should still be self-stabilizing too, because of the DC drop across the
output load inductor.



Audio tends to be nonsense, but at least the audio guys have fun
playing with circuits, whether they make a lot of sense or not.


Yup!


John




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Bitrex Bitrex is offline
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Default another bizarre audio circuit

On 3/2/2011 3:11 PM, Bitrex wrote:
On 3/2/2011 11:40 AM, John Larkin wrote:


I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

but it occurred to me that it might also make a nice headphone amp...

ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG


Neat, like a parafeed amplifier. The choke will have to be pretty big
for audio frequencies...

I can think of a modification that would give more gain for the negative
feedback to "work" with: change the input transistor to a JFET, get rid
of the capacitor and extra resistor in the bias stabilization circuit,
and just stick a resistor in the emitter lead of the output transistor.
Then, move the load resistor of the first stage down and connect an NPN
transistor with a current limiting resistor to the output between that
load resistor and the power supply. If I've figured things out correctly
you then have a gyrator load for the first stage. The bias should still
be self-stabilizing too, because of the DC drop across the output load
inductor.


Nope, sorry, cancel that, it won't work. The output stage has gain and
the gyrator won't work properly.
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John Larkin John Larkin is offline
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On Wed, 02 Mar 2011 15:11:37 -0500, Bitrex
wrote:

On 3/2/2011 11:40 AM, John Larkin wrote:


I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

but it occurred to me that it might also make a nice headphone amp...

ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG


Neat, like a parafeed amplifier. The choke will have to be pretty big
for audio frequencies...


You could just use a power resistor and tweak the drain voltage
operating point. It's just not as elegant.

John




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John Larkin John Larkin is offline
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Default another bizarre audio circuit

On Wed, 2 Mar 2011 12:03:38 -0800 (PST), Fred Bloggs
wrote:

On Mar 2, 11:40*am, John Larkin
wrote:
I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

but it occurred to me that it might also make a nice headphone amp...

ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG

Audio tends to be nonsense, but at least the audio guys have fun
playing with circuits, whether they make a lot of sense or not.

John


Bizarre??? Just a standard buffered input CE with negative feedback DC
bias to stabilize the operating point against Vbe and reverse leakage
collector current change with temperature- a textbook circuit...


Which textbook?

John

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Bitrex Bitrex is offline
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On 3/2/2011 4:32 PM, John Larkin wrote:
On Wed, 02 Mar 2011 15:11:37 -0500, Bitrex
wrote:

On 3/2/2011 11:40 AM, John Larkin wrote:


I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

but it occurred to me that it might also make a nice headphone amp...

ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG


Neat, like a parafeed amplifier. The choke will have to be pretty big
for audio frequencies...


You could just use a power resistor and tweak the drain voltage
operating point. It's just not as elegant.

John



The circuit I'm working on now as my "exercise in simplicity" from the
thread a while back uses another transistor for the load on the output
stage, simulating an inductor. This also has the advantage in Class A
of being able to set the idle current to half of the desired maximum
output current, instead of the usual need to set the idle at the full
output current.

If I remember correctly I think if one uses a resistive load the
quiescent idle current will have to be _more_ than the maximum output
current to get the desired output current into the load when the
transistor shuts down, because of the drop across the resistor.

I think I have an unhealthy obsession with simulated inductors.
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Arny Krueger Arny Krueger is offline
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Default another bizarre audio circuit

"John Larkin"
wrote in message

On Wed, 2 Mar 2011 12:03:38 -0800 (PST), Fred Bloggs
wrote:

On Mar 2, 11:40 am, John Larkin
wrote:
I've always sort of liked the classic "GE" tape
head/mic preamp circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

but it occurred to me that it might also make a nice
headphone amp...

ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG

Audio tends to be nonsense, but at least the audio guys
have fun playing with circuits, whether they make a lot
of sense or not.

John


Bizarre??? Just a standard buffered input CE with
negative feedback DC bias to stabilize the operating
point against Vbe and reverse leakage collector current
change with temperature- a textbook circuit...


Which textbook?


I don't know about textbooks, but it was a pretty standard circuit back in
1965 when I built a high performance RIAA preamp as an undergraduate project
as part work for my degree in engineering. if memory serves, it was in the
RCA transistor manual. I later built a number of these as standard parts of
Heathkits.

And voila, here's a schematic of a Dyna PAT-4 with essentually the same
circuit:

http://home.comcast.net/~g.e.dunn/PAT4/schem.jpg

The challenge that I had in 1965 was to build it using PNP germanium
switching transistors which weren't all that linear, were speced for beta =
20 and had no noise spec. The prof made a tactical error that he corrected
the next year - he didn't specify how many transistors or any other parts
that I was limited to use.

So, I built two amps with the circuit illustrated above, cascaded them, and
used 4 darlington pairs for the transistors, rather neatly solving the beta
problem. If memory serves the first stage was RIAA and the second was flat
with a gain of 10.

The thing ran rings around any commercial circuit that we compared it to,
whether SS or tubed both on the bench and in listening tests. In my travels
through the lab's parts bin, I also found a stash of appropriate-valued mil
spec metal film resistors, etc. As a commerical product, it might have had
to sell for $100s.


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m II m II is offline
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"Arny Krueger" wrote in message
news
"John Larkin"
wrote in message

On Wed, 2 Mar 2011 12:03:38 -0800 (PST), Fred Bloggs
wrote:

On Mar 2, 11:40 am, John Larkin
wrote:
I've always sort of liked the classic "GE" tape
head/mic preamp circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

but it occurred to me that it might also make a nice
headphone amp...

ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG

Audio tends to be nonsense, but at least the audio guys
have fun playing with circuits, whether they make a lot
of sense or not.

John


Bizarre??? Just a standard buffered input CE with
negative feedback DC bias to stabilize the operating
point against Vbe and reverse leakage collector current
change with temperature- a textbook circuit...


Which textbook?


I don't know about textbooks, but it was a pretty standard circuit back in
1965 when I built a high performance RIAA preamp as an undergraduate project
as part work for my degree in engineering. if memory serves, it was in the
RCA transistor manual. I later built a number of these as standard parts of
Heathkits.

And voila, here's a schematic of a Dyna PAT-4 with essentually the same
circuit:

http://home.comcast.net/~g.e.dunn/PAT4/schem.jpg

The challenge that I had in 1965 was to build it using PNP germanium
switching transistors which weren't all that linear, were speced for beta =
20 and had no noise spec. The prof made a tactical error that he corrected
the next year - he didn't specify how many transistors or any other parts
that I was limited to use.

So, I built two amps with the circuit illustrated above, cascaded them, and
used 4 darlington pairs for the transistors, rather neatly solving the beta
problem. If memory serves the first stage was RIAA and the second was flat
with a gain of 10.

The thing ran rings around any commercial circuit that we compared it to,
whether SS or tubed both on the bench and in listening tests. In my travels
through the lab's parts bin, I also found a stash of appropriate-valued mil
spec metal film resistors, etc. As a commerical product, it might have had
to sell for $100s.

----

Jeeezzzz You must be old.

I remember cutting my teeth on my first big project in 1968 on a Heathkit
stereo amplifier. The RIAA network was a secret bunch of components
encapsulated so the user could not tell what hidden secrets were installed.

I finally through that kit out a few years ago on a move cleanup. Many
repairs taught me a few things about power transistor output circuits and
why to not increase the length of the speaker connection screws until they
hit the chassis out the back of the terminal strips. Even took a few
warranty repairs at the shop. After about 6 sets of output transistor
replacements it came back with clearance holes behind them....duh!


mike


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John Larkin John Larkin is offline
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On Wed, 2 Mar 2011 17:24:13 -0500, "Arny Krueger"
wrote:

"John Larkin"
wrote in message

On Wed, 2 Mar 2011 12:03:38 -0800 (PST), Fred Bloggs
wrote:

On Mar 2, 11:40 am, John Larkin
wrote:
I've always sort of liked the classic "GE" tape
head/mic preamp circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

but it occurred to me that it might also make a nice
headphone amp...

ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG

Audio tends to be nonsense, but at least the audio guys
have fun playing with circuits, whether they make a lot
of sense or not.

John


Bizarre??? Just a standard buffered input CE with
negative feedback DC bias to stabilize the operating
point against Vbe and reverse leakage collector current
change with temperature- a textbook circuit...


Which textbook?


I don't know about textbooks, but it was a pretty standard circuit back in
1965 when I built a high performance RIAA preamp as an undergraduate project
as part work for my degree in engineering. if memory serves, it was in the
RCA transistor manual. I later built a number of these as standard parts of
Heathkits.


I used to design language labs and recording studios/mixers, and we
used that circuit a lot for tape heads and mic amps. It was called
"the GE circuit", don't know why.


And voila, here's a schematic of a Dyna PAT-4 with essentually the same
circuit:

http://home.comcast.net/~g.e.dunn/PAT4/schem.jpg

The challenge that I had in 1965 was to build it using PNP germanium
switching transistors which weren't all that linear, were speced for beta =
20 and had no noise spec. The prof made a tactical error that he corrected
the next year - he didn't specify how many transistors or any other parts
that I was limited to use.


I think I used 2N3391s, silicon NPNs, which were the black [1] GE
cylindrical epoxy transistors with the flange on the bottom and the
concave top, where they poured the epoxy in. 1968, approximately.

People here were discussing a low-parts-count headphone amp, and it
occurred to me that this configuration is a lot of bang for a few
parts, as a power amp. I thought the bipolar-mosfet thing was cute,
but then I'm easily amused.

John

[1] their early ones used brown epoxy and were photosensitive.




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John Larkin John Larkin is offline
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On Wed, 02 Mar 2011 16:50:46 -0500, Bitrex
wrote:

On 3/2/2011 4:32 PM, John Larkin wrote:
On Wed, 02 Mar 2011 15:11:37 -0500, Bitrex
wrote:

On 3/2/2011 11:40 AM, John Larkin wrote:


I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

but it occurred to me that it might also make a nice headphone amp...

ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG


Neat, like a parafeed amplifier. The choke will have to be pretty big
for audio frequencies...


You could just use a power resistor and tweak the drain voltage
operating point. It's just not as elegant.

John



The circuit I'm working on now as my "exercise in simplicity" from the
thread a while back uses another transistor for the load on the output
stage, simulating an inductor. This also has the advantage in Class A
of being able to set the idle current to half of the desired maximum
output current, instead of the usual need to set the idle at the full
output current.

If I remember correctly I think if one uses a resistive load the
quiescent idle current will have to be _more_ than the maximum output
current to get the desired output current into the load when the
transistor shuts down, because of the drop across the resistor.


Yes, you can swing almost all the way to the rails with a
constant-current load, as opposed to a resistor, so it's more
efficient... like an inductor. The inductor allows close to 2x Vcc p-p
voltage swing, if that matters.

But the constant-current load bumps the active parts count by 50% !!!

I think you could do a nice headphone amp with one mosfet. Or go nuts
and use a GaN fet.

John

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On Mar 2, 4:33*pm, John Larkin
wrote:
On Wed, 2 Mar 2011 12:03:38 -0800 (PST), Fred Bloggs





wrote:
On Mar 2, 11:40 am, John Larkin
wrote:
I've always sort of liked the classic "GE" tape head/mic preamp
circuit:


ftp://jjlarkin.lmi.net/GEcircuit.jpg


but it occurred to me that it might also make a nice headphone amp...


ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG


Audio tends to be nonsense, but at least the audio guys have fun
playing with circuits, whether they make a lot of sense or not.


John


Bizarre??? Just a standard buffered input CE with negative feedback DC
bias to stabilize the operating point against Vbe and reverse leakage
collector current change with temperature- a textbook circuit...


Which textbook?

John- Hide quoted text -

- Show quoted text -


Just about any textbook that goes into bias point sensitivity analysis
of transistor circuits- you remember the S- functions, mainly ICQ
stability. The big three were HFE, VBE, and ICBO. Then the rest of
your circuit is just ac-bypass and the shunt-series feedback for
signals. I've seen it dozens of times.
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On Wed, 2 Mar 2011 14:55:18 -0800 (PST), Fred Bloggs
wrote:

On Mar 2, 4:33*pm, John Larkin
wrote:
On Wed, 2 Mar 2011 12:03:38 -0800 (PST), Fred Bloggs





wrote:
On Mar 2, 11:40 am, John Larkin
wrote:
I've always sort of liked the classic "GE" tape head/mic preamp
circuit:


ftp://jjlarkin.lmi.net/GEcircuit.jpg


but it occurred to me that it might also make a nice headphone amp...


ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG


Audio tends to be nonsense, but at least the audio guys have fun
playing with circuits, whether they make a lot of sense or not.


John


Bizarre??? Just a standard buffered input CE with negative feedback DC
bias to stabilize the operating point against Vbe and reverse leakage
collector current change with temperature- a textbook circuit...


Which textbook?

John- Hide quoted text -

- Show quoted text -


Just about any textbook that goes into bias point sensitivity analysis
of transistor circuits- you remember the S- functions, mainly ICQ
stability. The big three were HFE, VBE, and ICBO. Then the rest of
your circuit is just ac-bypass and the shunt-series feedback for
signals. I've seen it dozens of times.


I bet you haven't seen the bipolar+mosfet version, with inductive
pullup, used as a power amp.

John

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Vladimir Vassilevsky[_2_] Vladimir Vassilevsky[_2_] is offline
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Default another bizarre audio circuit



John Larkin wrote:


I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg


Here is a couple of very low noise audio circuits for the same purpose:

http://www.abvolt.com/misc/inputs_audio.jpg

I like BJT and JFET in cascode.


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com

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On Wed, 02 Mar 2011 17:21:23 -0600, Vladimir Vassilevsky
wrote:



John Larkin wrote:


I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg


Here is a couple of very low noise audio circuits for the same purpose:

http://www.abvolt.com/misc/inputs_audio.jpg

I like BJT and JFET in cascode.


The one on the left, with the base and gate connected, is sure cute.


John



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Default another bizarre audio circuit

On Mar 2, 5:58*pm, John Larkin
wrote:
On Wed, 2 Mar 2011 14:55:18 -0800 (PST), Fred Bloggs





wrote:
On Mar 2, 4:33 pm, John Larkin
wrote:
On Wed, 2 Mar 2011 12:03:38 -0800 (PST), Fred Bloggs


wrote:
On Mar 2, 11:40 am, John Larkin
wrote:
I've always sort of liked the classic "GE" tape head/mic preamp
circuit:


ftp://jjlarkin.lmi.net/GEcircuit.jpg


but it occurred to me that it might also make a nice headphone amp....


ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG


Audio tends to be nonsense, but at least the audio guys have fun
playing with circuits, whether they make a lot of sense or not.


John


Bizarre??? Just a standard buffered input CE with negative feedback DC
bias to stabilize the operating point against Vbe and reverse leakage
collector current change with temperature- a textbook circuit...


Which textbook?


John- Hide quoted text -


- Show quoted text -


Just about any textbook that goes into bias point sensitivity analysis
of transistor circuits- you remember the S- functions, mainly ICQ
stability. The big three were HFE, VBE, and ICBO. Then the rest of
your circuit is just ac-bypass and the shunt-series feedback for
signals. I've seen it dozens of times.


I bet you haven't seen the bipolar+mosfet version, with inductive
pullup, used as a power amp.

John- Hide quoted text -

- Show quoted text -


I believe the collector inductor and/or transformer are used to
significantly increase the efficiency of the output stage, where that
consideration outweighs the additional cost.
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Bitrex Bitrex is offline
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Default another bizarre audio circuit

On 3/2/2011 6:30 PM, John Larkin wrote:
On Wed, 02 Mar 2011 17:21:23 -0600, Vladimir Vassilevsky
wrote:



John Larkin wrote:


I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg


Here is a couple of very low noise audio circuits for the same purpose:

http://www.abvolt.com/misc/inputs_audio.jpg

I like BJT and JFET in cascode.


The one on the left, with the base and gate connected, is sure cute.


John


I'm having a little trouble with the operation of that one. The way
it's set up, assuming the output sits at 0 volts won't the input BJT be
cut off?
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John Fields John Fields is offline
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On Wed, 02 Mar 2011 08:40:42 -0800, John Larkin
wrote:



I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

but it occurred to me that it might also make a nice headphone amp...

ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG


Audio tends to be nonsense, but at least the audio guys have fun
playing with circuits, whether they make a lot of sense or not.

John


---
Even though you scorn and ridicule audio, there's nothing wrong with
anyone seeking perfection there, just as there's nothing wrong with
your search for perfection in the genre which pleases _you_ to pursue.
So, speaking of fun, why don't you do a complete design and assign
values to the circuit components and identify the semiconductors?

Or is that legwork _we're_ supposed to do in order to flesh out your
divine revelation?

---
JF
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On Wed, 02 Mar 2011 19:26:29 -0500, Bitrex
wrote:

On 3/2/2011 6:30 PM, John Larkin wrote:
On Wed, 02 Mar 2011 17:21:23 -0600, Vladimir Vassilevsky
wrote:



John Larkin wrote:


I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

Here is a couple of very low noise audio circuits for the same purpose:

http://www.abvolt.com/misc/inputs_audio.jpg

I like BJT and JFET in cascode.


The one on the left, with the base and gate connected, is sure cute.


John


I'm having a little trouble with the operation of that one. The way
it's set up, assuming the output sits at 0 volts won't the input BJT be
cut off?


Jfets usually run at negative gate voltage. Assume the transistor base
is at +0.7. The jfet source will be at some more positive voltage,
+2.5 maybe. That's enough to run the transistor.

Actually, you can cascode a transistor into the source of a fet that
has a grounded gate. In that case, the source/collector voltage might
be a volt or two. You would have to look at the fet transfer curve,
and know the design operating current, to see exactly what that
voltage might be.

The problem with jfets is the huge part-to-part variation in Idss and
transfer curves. A 10:1 datasheet spread in Idss isn't unusual.





+10v
|
|
|
d
gnd---------g
s
|
|
+------ Vs
|
|
10K
|
|
|
gnd

For a typical vanilla jfet in this circuit, Vs might be +1 to +4 volts
maybe.

John



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On Wed, 02 Mar 2011 18:36:25 -0600, John Fields
wrote:

On Wed, 02 Mar 2011 08:40:42 -0800, John Larkin
wrote:



I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

but it occurred to me that it might also make a nice headphone amp...

ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG


Audio tends to be nonsense, but at least the audio guys have fun
playing with circuits, whether they make a lot of sense or not.

John


---
Even though you scorn and ridicule audio, there's nothing wrong with
anyone seeking perfection there, just as there's nothing wrong with
your search for perfection in the genre which pleases _you_ to pursue.
So, speaking of fun, why don't you do a complete design and assign
values to the circuit components and identify the semiconductors?


You're not playing the game. You are sitting in the henhouse, clucking
about the people who do.

Or is that legwork _we're_ supposed to do in order to flesh out your
divine revelation?


Chickenleg work!

John



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On 3/2/2011 8:06 PM, John Larkin wrote:
On Wed, 02 Mar 2011 19:26:29 -0500, Bitrex
wrote:

On 3/2/2011 6:30 PM, John Larkin wrote:
On Wed, 02 Mar 2011 17:21:23 -0600, Vladimir Vassilevsky
wrote:



John Larkin wrote:


I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

Here is a couple of very low noise audio circuits for the same purpose:

http://www.abvolt.com/misc/inputs_audio.jpg

I like BJT and JFET in cascode.


The one on the left, with the base and gate connected, is sure cute.


John


I'm having a little trouble with the operation of that one. The way
it's set up, assuming the output sits at 0 volts won't the input BJT be
cut off?


Jfets usually run at negative gate voltage. Assume the transistor base
is at +0.7. The jfet source will be at some more positive voltage,
+2.5 maybe. That's enough to run the transistor.

Yep - I'm not a complete "n00b"... What I mean though is with
that circuit with the input BJT's emitter at ground if its base is at
0.7 volts the minute its base goes negative it's going to cut off.
Maybe the emitter should be connected to the negative supply?


Actually, you can cascode a transistor into the source of a fet that
has a grounded gate. In that case, the source/collector voltage might
be a volt or two. You would have to look at the fet transfer curve,
and know the design operating current, to see exactly what that
voltage might be.


I'm foggy on how such a cascode reduces noise - improved distortion,
bandwidth, and PSRR I can understand but how does two transistors end up
less noisy than one? I know with tubes a cascode was considered a low
noise alternative since two triodes in cascode would have lower noise
than a single pentode, with similar gain.


The problem with jfets is the huge part-to-part variation in Idss and
transfer curves. A 10:1 datasheet spread in Idss isn't unusual.





+10v
|
|
|
d
gnd---------g
s
|
|
+------ Vs
|
|
10K
|
|
|
gnd

For a typical vanilla jfet in this circuit, Vs might be +1 to +4 volts
maybe.

John




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Bill Sloman Bill Sloman is offline
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On Mar 3, 2:11*am, John Larkin
wrote:
On Wed, 02 Mar 2011 18:36:25 -0600, John Fields



wrote:
On Wed, 02 Mar 2011 08:40:42 -0800, John Larkin
wrote:


I've always sort of liked the classic "GE" tape head/mic preamp
circuit:


ftp://jjlarkin.lmi.net/GEcircuit.jpg


but it occurred to me that it might also make a nice headphone amp...


ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG


Audio tends to be nonsense, but at least the audio guys have fun
playing with circuits, whether they make a lot of sense or not.


John


---
Even though you scorn and ridicule audio, there's nothing wrong with
anyone seeking perfection there, just as there's nothing wrong with
your search for perfection in the genre which pleases _you_ to pursue.
So, speaking of fun, why don't you do a complete design and assign
values to the circuit components and identify the semiconductors?


You're not playing the game. You are sitting in the henhouse, clucking
about the people who do.


He's not playing your game, which involves telling John Larkin how
cute his circuits are.

Or is that legwork _we're_ supposed to do in order to flesh out your
divine revelation?


Chickenleg work!


It's half the story - a few component values make it a lot easier to
work out what a circuit is doing.

--
Bill Sloman, Nijmegen
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Default another bizarre audio circuit

On Wed, 02 Mar 2011 20:51:17 -0500, Bitrex
wrote:

On 3/2/2011 8:06 PM, John Larkin wrote:
On Wed, 02 Mar 2011 19:26:29 -0500, Bitrex
wrote:

On 3/2/2011 6:30 PM, John Larkin wrote:
On Wed, 02 Mar 2011 17:21:23 -0600, Vladimir Vassilevsky
wrote:



John Larkin wrote:


I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

Here is a couple of very low noise audio circuits for the same purpose:

http://www.abvolt.com/misc/inputs_audio.jpg

I like BJT and JFET in cascode.


The one on the left, with the base and gate connected, is sure cute.


John


I'm having a little trouble with the operation of that one. The way
it's set up, assuming the output sits at 0 volts won't the input BJT be
cut off?


Jfets usually run at negative gate voltage. Assume the transistor base
is at +0.7. The jfet source will be at some more positive voltage,
+2.5 maybe. That's enough to run the transistor.

Yep - I'm not a complete "n00b"... What I mean though is with
that circuit with the input BJT's emitter at ground if its base is at
0.7 volts the minute its base goes negative it's going to cut off.


That's what transistors do!



Maybe the emitter should be connected to the negative supply?


Actually, you can cascode a transistor into the source of a fet that
has a grounded gate. In that case, the source/collector voltage might
be a volt or two. You would have to look at the fet transfer curve,
and know the design operating current, to see exactly what that
voltage might be.


I'm foggy on how such a cascode reduces noise - improved distortion,
bandwidth, and PSRR I can understand but how does two transistors end up
less noisy than one? I know with tubes a cascode was considered a low
noise alternative since two triodes in cascode would have lower noise
than a single pentode, with similar gain.



Actually, in Vlad's circuit, the cascode probably doesn't help much.
But it sure is cute!

John


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Bitrex Bitrex is offline
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Default another bizarre audio circuit

On 3/2/2011 8:59 PM, John Larkin wrote:
On Wed, 02 Mar 2011 20:51:17 -0500, Bitrex
wrote:

On 3/2/2011 8:06 PM, John Larkin wrote:
On Wed, 02 Mar 2011 19:26:29 -0500, Bitrex
wrote:

On 3/2/2011 6:30 PM, John Larkin wrote:
On Wed, 02 Mar 2011 17:21:23 -0600, Vladimir Vassilevsky
wrote:



John Larkin wrote:


I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

Here is a couple of very low noise audio circuits for the same purpose:

http://www.abvolt.com/misc/inputs_audio.jpg

I like BJT and JFET in cascode.


The one on the left, with the base and gate connected, is sure cute.


John


I'm having a little trouble with the operation of that one. The way
it's set up, assuming the output sits at 0 volts won't the input BJT be
cut off?

Jfets usually run at negative gate voltage. Assume the transistor base
is at +0.7. The jfet source will be at some more positive voltage,
+2.5 maybe. That's enough to run the transistor.

Yep - I'm not a complete "n00b"... What I mean though is with
that circuit with the input BJT's emitter at ground if its base is at
0.7 volts the minute its base goes negative it's going to cut off.


That's what transistors do!



Right, but the gain of that stage is going to be very unsymmetrical. I
guess with so much gain and the negative feedback it doesn't matter though.

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Default another bizarre audio circuit

On Wed, 2 Mar 2011 17:59:58 -0800 (PST), Bill Sloman
wrote:

On Mar 3, 2:11*am, John Larkin
wrote:
On Wed, 02 Mar 2011 18:36:25 -0600, John Fields



wrote:
On Wed, 02 Mar 2011 08:40:42 -0800, John Larkin
wrote:


I've always sort of liked the classic "GE" tape head/mic preamp
circuit:


ftp://jjlarkin.lmi.net/GEcircuit.jpg


but it occurred to me that it might also make a nice headphone amp...


ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG


Audio tends to be nonsense, but at least the audio guys have fun
playing with circuits, whether they make a lot of sense or not.


John


---
Even though you scorn and ridicule audio, there's nothing wrong with
anyone seeking perfection there, just as there's nothing wrong with
your search for perfection in the genre which pleases _you_ to pursue.
So, speaking of fun, why don't you do a complete design and assign
values to the circuit components and identify the semiconductors?


You're not playing the game. You are sitting in the henhouse, clucking
about the people who do.


He's not playing your game, which involves telling John Larkin how
cute his circuits are.


He's not designing circuits, which is what this newsgroup is about.

You aren't either. Both of you start to cluck and peck when people do
design circuits. No surprise.



Or is that legwork _we're_ supposed to do in order to flesh out your
divine revelation?


Chickenleg work!


It's half the story - a few component values make it a lot easier to
work out what a circuit is doing.


You can't look at a circuit this simple and see what it's doing? OK,
no surprise.

John



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John - KD5YI John - KD5YI is offline
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Posts: 11
Default another bizarre audio circuit

On 3/2/2011 8:32 PM, John Larkin wrote:
On Wed, 2 Mar 2011 17:59:58 -0800 (PST), Bill Sloman
wrote:

On Mar 3, 2:11 am, John Larkin
wrote:
On Wed, 02 Mar 2011 18:36:25 -0600, John Fields



wrote:
On Wed, 02 Mar 2011 08:40:42 -0800, John Larkin
wrote:

I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

but it occurred to me that it might also make a nice headphone amp...

ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG

Audio tends to be nonsense, but at least the audio guys have fun
playing with circuits, whether they make a lot of sense or not.

John

---
Even though you scorn and ridicule audio, there's nothing wrong with
anyone seeking perfection there, just as there's nothing wrong with
your search for perfection in the genre which pleases _you_ to pursue.
So, speaking of fun, why don't you do a complete design and assign
values to the circuit components and identify the semiconductors?

You're not playing the game. You are sitting in the henhouse, clucking
about the people who do.


He's not playing your game, which involves telling John Larkin how
cute his circuits are.


He's not designing circuits, which is what this newsgroup is about.

You aren't either. Both of you start to cluck and peck when people do
design circuits. No surprise.



Or is that legwork _we're_ supposed to do in order to flesh out your
divine revelation?

Chickenleg work!


It's half the story - a few component values make it a lot easier to
work out what a circuit is doing.


You can't look at a circuit this simple and see what it's doing? OK,
no surprise.

John


Well, I thought designing a circuit included supplying component values.
No?

  #27   Report Post  
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John Larkin John Larkin is offline
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Posts: 151
Default another bizarre audio circuit

On Wed, 02 Mar 2011 20:40:27 -0600, John - KD5YI
wrote:

On 3/2/2011 8:32 PM, John Larkin wrote:
On Wed, 2 Mar 2011 17:59:58 -0800 (PST), Bill Sloman
wrote:

On Mar 3, 2:11 am, John Larkin
wrote:
On Wed, 02 Mar 2011 18:36:25 -0600, John Fields



wrote:
On Wed, 02 Mar 2011 08:40:42 -0800, John Larkin
wrote:

I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

but it occurred to me that it might also make a nice headphone amp...

ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG

Audio tends to be nonsense, but at least the audio guys have fun
playing with circuits, whether they make a lot of sense or not.

John

---
Even though you scorn and ridicule audio, there's nothing wrong with
anyone seeking perfection there, just as there's nothing wrong with
your search for perfection in the genre which pleases _you_ to pursue.
So, speaking of fun, why don't you do a complete design and assign
values to the circuit components and identify the semiconductors?

You're not playing the game. You are sitting in the henhouse, clucking
about the people who do.

He's not playing your game, which involves telling John Larkin how
cute his circuits are.


He's not designing circuits, which is what this newsgroup is about.

You aren't either. Both of you start to cluck and peck when people do
design circuits. No surprise.



Or is that legwork _we're_ supposed to do in order to flesh out your
divine revelation?

Chickenleg work!

It's half the story - a few component values make it a lot easier to
work out what a circuit is doing.


You can't look at a circuit this simple and see what it's doing? OK,
no surprise.

John


Well, I thought designing a circuit included supplying component values.
No?


I posted topologies. Values can be scaled to the application, but you
need a topology first. If I were actually going to build this, for
money, of course I'd have to define specs and then compute values.
That's just grunt work.

John

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TheQuickBrownFox TheQuickBrownFox is offline
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Posts: 7
Default another bizarre audio circuit

On Wed, 02 Mar 2011 17:11:41 -0800, John Larkin
wrote:

You're not playing the game. You are sitting in the henhouse, clucking
about the people who do.



You sound like one of these punks they put on TV that spews nonsense as
if it was once a colloquialism.

You know nothing about folks here, yet you constantly spout off little
particulars from the depths of YOUR brain, and attribute them to those
you attack as if they are factual.

You are worse than the poorly raised punk ****s that are all over the
streets. They have an excuse. You were supposed to remember your
upbringing, yet you thumb your nose at that and everyone around you ,
which *you* have decided belong on your personal **** list.

You are almost as immature as Terrell, and that is at a very close
second.

Hey John... Grow the **** up.
  #29   Report Post  
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MakeNoAttemptToAdjustYourSet MakeNoAttemptToAdjustYourSet is offline
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Posts: 3
Default another bizarre audio circuit

On Wed, 02 Mar 2011 18:32:42 -0800, John Larkin
wrote:

He's not designing circuits, which is what this newsgroup is about.


Bull****. You do not know the facts in the first case you cite, and
you are off the mark in the second case you cite.

Electronics is far more than a mere circuit. There are several
physical disciplines involved. This group is about ALL aspects of the
science of electronics design, and that extends BEYOND only circuits.

Grow the **** up, you mouthy little school marm wanna be bitch!

You have no clue what John does or does not do.

So you need to grow the **** up in that respect as well, you ****y
little bitch.
  #30   Report Post  
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John Larkin John Larkin is offline
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Posts: 151
Default another bizarre audio circuit

On Wed, 02 Mar 2011 19:53:37 -0800, MakeNoAttemptToAdjustYourSet
wrote:

On Wed, 02 Mar 2011 18:32:42 -0800, John Larkin
wrote:

He's not designing circuits, which is what this newsgroup is about.


Bull****. You do not know the facts in the first case you cite, and
you are off the mark in the second case you cite.

Electronics is far more than a mere circuit. There are several
physical disciplines involved. This group is about ALL aspects of the
science of electronics design, and that extends BEYOND only circuits.


Word salad.


Grow the **** up, you mouthy little school marm wanna be bitch!

You have no clue what John does or does not do.


JF? He clucks. Like you, he doesn't post circuits.

Well, maybe once in a great while. To my knowledge, you have never
posted a circuit, or shown any evidence that you know how to design
electronics.


So you need to grow the **** up in that respect as well, you ****y
little bitch.


Show is some circuits, Big Man. How about an original headphone amp?

John



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Posts: 151
Default another bizarre audio circuit

On Wed, 02 Mar 2011 19:49:28 -0800, TheQuickBrownFox
wrote:

On Wed, 02 Mar 2011 17:11:41 -0800, John Larkin
wrote:

You're not playing the game. You are sitting in the henhouse, clucking
about the people who do.



You sound like one of these punks they put on TV that spews nonsense as
if it was once a colloquialism.

You know nothing about folks here, yet you constantly spout off little
particulars from the depths of YOUR brain, and attribute them to those
you attack as if they are factual.

You are worse than the poorly raised punk ****s that are all over the
streets. They have an excuse. You were supposed to remember your
upbringing, yet you thumb your nose at that and everyone around you ,
which *you* have decided belong on your personal **** list.

You are almost as immature as Terrell, and that is at a very close
second.

Hey John... Grow the **** up.


Hey, DimmerMan, post us a circuit.

John

  #32   Report Post  
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John - KD5YI John - KD5YI is offline
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Posts: 11
Default another bizarre audio circuit

On 3/2/2011 8:52 PM, John Larkin wrote:
On Wed, 02 Mar 2011 20:40:27 -0600, John -
wrote:

On 3/2/2011 8:32 PM, John Larkin wrote:
On Wed, 2 Mar 2011 17:59:58 -0800 (PST), Bill Sloman
wrote:

On Mar 3, 2:11 am, John Larkin
wrote:
On Wed, 02 Mar 2011 18:36:25 -0600, John Fields



wrote:
On Wed, 02 Mar 2011 08:40:42 -0800, John Larkin
wrote:

I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

but it occurred to me that it might also make a nice headphone amp...

ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG

Audio tends to be nonsense, but at least the audio guys have fun
playing with circuits, whether they make a lot of sense or not.

John

---
Even though you scorn and ridicule audio, there's nothing wrong with
anyone seeking perfection there, just as there's nothing wrong with
your search for perfection in the genre which pleases _you_ to pursue.
So, speaking of fun, why don't you do a complete design and assign
values to the circuit components and identify the semiconductors?

You're not playing the game. You are sitting in the henhouse, clucking
about the people who do.

He's not playing your game, which involves telling John Larkin how
cute his circuits are.

He's not designing circuits, which is what this newsgroup is about.

You aren't either. Both of you start to cluck and peck when people do
design circuits. No surprise.



Or is that legwork _we're_ supposed to do in order to flesh out your
divine revelation?

Chickenleg work!

It's half the story - a few component values make it a lot easier to
work out what a circuit is doing.

You can't look at a circuit this simple and see what it's doing? OK,
no surprise.

John


Well, I thought designing a circuit included supplying component values.
No?


I posted topologies. Values can be scaled to the application, but you
need a topology first. If I were actually going to build this, for
money, of course I'd have to define specs and then compute values.
That's just grunt work.

John


Not really. I have a few circuits I could throw out and claim that they
are topologies and you would not be able to use them without values.
Granted, mine are more complex than the one being discussed, but I'm
hoping to make a point.

John (not Larkin)


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Posts: 11
Default another bizarre audio circuit

On 3/2/2011 10:02 PM, John Larkin wrote:
On Wed, 02 Mar 2011 19:53:37 -0800, MakeNoAttemptToAdjustYourSet
wrote:

On Wed, 02 Mar 2011 18:32:42 -0800, John Larkin
wrote:

He's not designing circuits, which is what this newsgroup is about.


Bull****. You do not know the facts in the first case you cite, and
you are off the mark in the second case you cite.

Electronics is far more than a mere circuit. There are several
physical disciplines involved. This group is about ALL aspects of the
science of electronics design, and that extends BEYOND only circuits.


Word salad.


Grow the **** up, you mouthy little school marm wanna be bitch!

You have no clue what John does or does not do.


JF? He clucks. Like you, he doesn't post circuits.

Well, maybe once in a great while. To my knowledge, you have never
posted a circuit, or shown any evidence that you know how to design
electronics.


So you need to grow the **** up in that respect as well, you ****y
little bitch.


Show us some circuits, Big Man. How about an original headphone amp?

John


Good challenge, John. I expect more word salad from him since he has
never shown any technical abilities. I expect mostly a host of profanities.

John (not Larson)

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TheQuickBrownFox TheQuickBrownFox is offline
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Posts: 7
Default another bizarre audio circuit

On Wed, 02 Mar 2011 22:06:41 -0600, John - KD5YI
wrote:

but I'm
hoping to make a point.


Consider the target. Impossible task.

He is hard wired stupid.
  #35   Report Post  
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John Larkin John Larkin is offline
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Posts: 151
Default another bizarre audio circuit

On Wed, 02 Mar 2011 22:06:41 -0600, John - KD5YI
wrote:

On 3/2/2011 8:52 PM, John Larkin wrote:
On Wed, 02 Mar 2011 20:40:27 -0600, John -
wrote:

On 3/2/2011 8:32 PM, John Larkin wrote:
On Wed, 2 Mar 2011 17:59:58 -0800 (PST), Bill Sloman
wrote:

On Mar 3, 2:11 am, John Larkin
wrote:
On Wed, 02 Mar 2011 18:36:25 -0600, John Fields



wrote:
On Wed, 02 Mar 2011 08:40:42 -0800, John Larkin
wrote:

I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

but it occurred to me that it might also make a nice headphone amp...

ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG

Audio tends to be nonsense, but at least the audio guys have fun
playing with circuits, whether they make a lot of sense or not.

John

---
Even though you scorn and ridicule audio, there's nothing wrong with
anyone seeking perfection there, just as there's nothing wrong with
your search for perfection in the genre which pleases _you_ to pursue.
So, speaking of fun, why don't you do a complete design and assign
values to the circuit components and identify the semiconductors?

You're not playing the game. You are sitting in the henhouse, clucking
about the people who do.

He's not playing your game, which involves telling John Larkin how
cute his circuits are.

He's not designing circuits, which is what this newsgroup is about.

You aren't either. Both of you start to cluck and peck when people do
design circuits. No surprise.



Or is that legwork _we're_ supposed to do in order to flesh out your
divine revelation?

Chickenleg work!

It's half the story - a few component values make it a lot easier to
work out what a circuit is doing.

You can't look at a circuit this simple and see what it's doing? OK,
no surprise.

John

Well, I thought designing a circuit included supplying component values.
No?


I posted topologies. Values can be scaled to the application, but you
need a topology first. If I were actually going to build this, for
money, of course I'd have to define specs and then compute values.
That's just grunt work.

John


Not really. I have a few circuits I could throw out and claim that they
are topologies and you would not be able to use them without values.
Granted, mine are more complex than the one being discussed, but I'm
hoping to make a point.

John (not Larkin)


I think circuit topologies are fun to play with. Lots of textbooks
show, and discuss, circuits without explicit values. Once you have a
topology, then you can proceed to specs and component values.

If you think all circuits should be posted with values, post some.

John



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Default another bizarre audio circuit

On Wed, 02 Mar 2011 22:11:11 -0600, John - KD5YI
wrote:

On 3/2/2011 10:02 PM, John Larkin wrote:
On Wed, 02 Mar 2011 19:53:37 -0800, MakeNoAttemptToAdjustYourSet
wrote:

On Wed, 02 Mar 2011 18:32:42 -0800, John Larkin
wrote:

He's not designing circuits, which is what this newsgroup is about.

Bull****. You do not know the facts in the first case you cite, and
you are off the mark in the second case you cite.

Electronics is far more than a mere circuit. There are several
physical disciplines involved. This group is about ALL aspects of the
science of electronics design, and that extends BEYOND only circuits.


Word salad.


Grow the **** up, you mouthy little school marm wanna be bitch!

You have no clue what John does or does not do.


JF? He clucks. Like you, he doesn't post circuits.

Well, maybe once in a great while. To my knowledge, you have never
posted a circuit, or shown any evidence that you know how to design
electronics.


So you need to grow the **** up in that respect as well, you ****y
little bitch.


Show us some circuits, Big Man. How about an original headphone amp?

John


Good challenge, John. I expect more word salad from him since he has
never shown any technical abilities. I expect mostly a host of profanities.

John (not Larson)


Moer proof of you utter stupidity. I have posted links several times
here to photo sites that have all of my library of photos that I feel
someone could see.

You were just your same old retarded self back then, and failed to
visit the photo bin.

You AND the Larkin John are ****ing absolute idiots.

Me? I work on Satellite gear and 10G Base gateways. The gear I am
configuring is the fastest gateways on the planet surface, and it will be
part of a huge backbone quite soon. Several gateways in several cities
are already in place.

On my slow days, I perform a specific repair on military radios that no
one else in the shop does, so our boys can stay safe. This involves
placing an EMI shield so that nothing spills out. Tempest standards are
pretty tough.

One of my favorite "modern" things to do is watching a design get
printed over on the 3D printer.

Remembering waiting by the dot matrix printer for a print job to
finish, then thinking about modern laser printers and their speed and
resolution, then seeing this "part" get "printed". We actually use them
too!

You can "print" a PCB test fixture mount and even place PEMs and such
in it.

We do this now before we send the frame out to get hard hobbed. Now
THAT is a fun machine. The laser for making labels and such is cool too.
Amazing what one can do with 45 Watts worth of amplified light and a
precision x y gantry.

Yes, I do both circuits AND mechanical layouts. I also work on the
radios. No, that is not engineering, it is skill management.
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[email protected] krw@att.bizzzzzzzzzzzz is offline
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Default another bizarre audio circuit

On Wed, 02 Mar 2011 22:11:11 -0600, John - KD5YI wrote:

On 3/2/2011 10:02 PM, John Larkin wrote:
On Wed, 02 Mar 2011 19:53:37 -0800, MakeNoAttemptToAdjustYourSet
wrote:

On Wed, 02 Mar 2011 18:32:42 -0800, John Larkin
wrote:

He's not designing circuits, which is what this newsgroup is about.

Bull****. You do not know the facts in the first case you cite, and
you are off the mark in the second case you cite.

Electronics is far more than a mere circuit. There are several
physical disciplines involved. This group is about ALL aspects of the
science of electronics design, and that extends BEYOND only circuits.


Word salad.


Grow the **** up, you mouthy little school marm wanna be bitch!

You have no clue what John does or does not do.


JF? He clucks. Like you, he doesn't post circuits.

Well, maybe once in a great while. To my knowledge, you have never
posted a circuit, or shown any evidence that you know how to design
electronics.


So you need to grow the **** up in that respect as well, you ****y
little bitch.


Show us some circuits, Big Man. How about an original headphone amp?

John


Good challenge, John. I expect more word salad from him since he has
never shown any technical abilities. I expect mostly a host of profanities.


Don't forget DimBulb's love of poop.
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John - KD5YI John - KD5YI is offline
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Default another bizarre audio circuit

On 3/2/2011 10:24 PM, John Larkin wrote:
On Wed, 02 Mar 2011 22:06:41 -0600, John -
wrote:

On 3/2/2011 8:52 PM, John Larkin wrote:
On Wed, 02 Mar 2011 20:40:27 -0600, John -
wrote:

On 3/2/2011 8:32 PM, John Larkin wrote:
On Wed, 2 Mar 2011 17:59:58 -0800 (PST), Bill Sloman
wrote:

On Mar 3, 2:11 am, John Larkin
wrote:
On Wed, 02 Mar 2011 18:36:25 -0600, John Fields



wrote:
On Wed, 02 Mar 2011 08:40:42 -0800, John Larkin
wrote:

I've always sort of liked the classic "GE" tape head/mic preamp
circuit:

ftp://jjlarkin.lmi.net/GEcircuit.jpg

but it occurred to me that it might also make a nice headphone amp...

ftp://jjlarkin.lmi.net/GE_headphone_amp.JPG

Audio tends to be nonsense, but at least the audio guys have fun
playing with circuits, whether they make a lot of sense or not.

John

---
Even though you scorn and ridicule audio, there's nothing wrong with
anyone seeking perfection there, just as there's nothing wrong with
your search for perfection in the genre which pleases _you_ to pursue.
So, speaking of fun, why don't you do a complete design and assign
values to the circuit components and identify the semiconductors?

You're not playing the game. You are sitting in the henhouse, clucking
about the people who do.

He's not playing your game, which involves telling John Larkin how
cute his circuits are.

He's not designing circuits, which is what this newsgroup is about.

You aren't either. Both of you start to cluck and peck when people do
design circuits. No surprise.



Or is that legwork _we're_ supposed to do in order to flesh out your
divine revelation?

Chickenleg work!

It's half the story - a few component values make it a lot easier to
work out what a circuit is doing.

You can't look at a circuit this simple and see what it's doing? OK,
no surprise.

John

Well, I thought designing a circuit included supplying component values.
No?

I posted topologies. Values can be scaled to the application, but you
need a topology first. If I were actually going to build this, for
money, of course I'd have to define specs and then compute values.
That's just grunt work.

John


Not really. I have a few circuits I could throw out and claim that they
are topologies and you would not be able to use them without values.
Granted, mine are more complex than the one being discussed, but I'm
hoping to make a point.

John (not Larkin)


I think circuit topologies are fun to play with. Lots of textbooks
show, and discuss, circuits without explicit values. Once you have a
topology, then you can proceed to specs and component values.

If you think all circuits should be posted with values, post some.

John


You are correct, John. Now you have a topology. Please post the
component values.

Thanks,
John

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On 3/2/2011 10:37 PM, zzzzzzzzzz wrote:
On Wed, 02 Mar 2011 22:11:11 -0600, John - wrote:

On 3/2/2011 10:02 PM, John Larkin wrote:
On Wed, 02 Mar 2011 19:53:37 -0800, MakeNoAttemptToAdjustYourSet
wrote:

On Wed, 02 Mar 2011 18:32:42 -0800, John Larkin
wrote:

He's not designing circuits, which is what this newsgroup is about.

Bull****. You do not know the facts in the first case you cite, and
you are off the mark in the second case you cite.

Electronics is far more than a mere circuit. There are several
physical disciplines involved. This group is about ALL aspects of the
science of electronics design, and that extends BEYOND only circuits.

Word salad.


Grow the **** up, you mouthy little school marm wanna be bitch!

You have no clue what John does or does not do.

JF? He clucks. Like you, he doesn't post circuits.

Well, maybe once in a great while. To my knowledge, you have never
posted a circuit, or shown any evidence that you know how to design
electronics.


So you need to grow the **** up in that respect as well, you ****y
little bitch.

Show us some circuits, Big Man. How about an original headphone amp?

John


Good challenge, John. I expect more word salad from him since he has
never shown any technical abilities. I expect mostly a host of profanities.


Don't forget DimBulb's love of poop.


Ah, yes. For some reason I don't think that much about feces like he does.


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John - KD5YI John - KD5YI is offline
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Default another bizarre audio circuit

On 3/2/2011 10:35 PM, MakeNoAttemptToAdjustYourSet wrote:
On Wed, 02 Mar 2011 22:11:11 -0600, John -
wrote:

On 3/2/2011 10:02 PM, John Larkin wrote:
On Wed, 02 Mar 2011 19:53:37 -0800, MakeNoAttemptToAdjustYourSet
wrote:

On Wed, 02 Mar 2011 18:32:42 -0800, John Larkin
wrote:

He's not designing circuits, which is what this newsgroup is about.

Bull****. You do not know the facts in the first case you cite, and
you are off the mark in the second case you cite.

Electronics is far more than a mere circuit. There are several
physical disciplines involved. This group is about ALL aspects of the
science of electronics design, and that extends BEYOND only circuits.

Word salad.


Grow the **** up, you mouthy little school marm wanna be bitch!

You have no clue what John does or does not do.

JF? He clucks. Like you, he doesn't post circuits.

Well, maybe once in a great while. To my knowledge, you have never
posted a circuit, or shown any evidence that you know how to design
electronics.


So you need to grow the **** up in that respect as well, you ****y
little bitch.

Show us some circuits, Big Man. How about an original headphone amp?

John


Good challenge, John. I expect more word salad from him since he has
never shown any technical abilities. I expect mostly a host of profanities.

John (not Larson)


Moer proof of you utter stupidity. I have posted links several times
here to photo sites that have all of my library of photos that I feel
someone could see.


Really? I could post a photo site of anyone I choose and you would not
have any idea they were not mine. I discard that claim of your proof of
technical abilities unless you can back it up.


You were just your same old retarded self back then, and failed to
visit the photo bin.

I am ****ing absolute idiot.

Me? I work on Satellite gear and 10G Base gateways.


Yes, I'm sure. They need technicians to clean them and return them to
service.

The gear I am
configuring is the fastest gateways on the planet surface, and it will be
part of a huge backbone quite soon. Several gateways in several cities
are already in place.


Configuring? Touching up the paint job, perhaps

On my slow days, I perform a specific repair on military radios that no
one else in the shop does, so our boys can stay safe. This involves
placing an EMI shield so that nothing spills out. Tempest standards are
pretty tough.


Sure. Hey, dip****.. get of the phone and put that EMI shield in that
radio like we told you!

One of my favorite "modern" things to do is watching a design get
printed over on the 3D printer.

Remembering waiting by the dot matrix printer for a print job to
finish, then thinking about modern laser printers and their speed and
resolution, then seeing this "part" get "printed". We actually use them
too!


Good God! You and your company are still using dot matrix printers?

Yes, I do both circuits AND mechanical layouts. I also work on the
radios. No, that is not engineering, it is skill management.


Jesus! You are the flunky everyone here has accused you of being. You
poor piece of crap. You've probably been sweeping and mopping the floors
all along and picked up enough words to make you seem important.

You're not worth playing with anymore. **** off.
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