one transistor amplifier help

[amdx]

I have the following amp.
It originally had a 12V supply voltage, In an effort to get a larger
swing on the output, I raised that to 24V.
I now get 12.5Vpp on the output, I want to maximize the output signal.
A gain of 3 will work for my circuit.
What changes can I make to maximize the output swing.
The input is at maximum before distortion is seen.

> https://www.dropbox.com/s/07jq88cqh8sxr7j/Kliejers%20amp%20ascii.jpg?dl=0

I would like to put matching load on the output so my swing will drop in
1/2.

Mikek

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[Jasen Betts]

On 2017-04-15, amdx <nojunk@knology.net> wrote:

I have the following amp.
It originally had a 12V supply voltage, In an effort to get a larger
swing on the output, I raised that to 24V.
I now get 12.5Vpp on the output, I want to maximize the output signal.
A gain of 3 will work for my circuit.
What changes can I make to maximize the output swing.
The input is at maximum before distortion is seen.

maybe

reduce R9, R10 to 39R
reduce R8 to something like 680 - your aimimg to get the collector to 13V



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This email has not been checked by half-arsed antivirus software

 

[Jim Thompson]

On Sat, 15 Apr 2017 10:18:32 -0500, amdx <nojunk@knology.net> wrote:

I have the following amp.
It originally had a 12V supply voltage, In an effort to get a larger
swing on the output, I raised that to 24V.
I now get 12.5Vpp on the output, I want to maximize the output signal.
A gain of 3 will work for my circuit.
What changes can I make to maximize the output swing.
The input is at maximum before distortion is seen.

https://www.dropbox.com/s/07jq88cqh8sxr7j/Kliejers%20amp%20ascii.jpg?dl=0

I would like to put matching load on the output so my swing will drop in
1/2.

Fundamental novice error... amplifier outputs should be LOW impedance
for maximum power transfer.

Mikek

What are you actually trying to accomplish? Input amplitude? Source
impedance? Gain (X3)? Load impedance?

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| STV, Queen Creek, AZ 85142 Skype: skypeanalog | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

Thinking outside the box... producing elegant solutions.

 

[amdx]

On 4/16/2017 4:07 PM, Jim Thompson wrote:

On Sat, 15 Apr 2017 10:18:32 -0500, amdx <nojunk@knology.net> wrote:

I have the following amp.
It originally had a 12V supply voltage, In an effort to get a larger
swing on the output, I raised that to 24V.
I now get 12.5Vpp on the output, I want to maximize the output signal.
A gain of 3 will work for my circuit.
What changes can I make to maximize the output swing.
The input is at maximum before distortion is seen.

https://www.dropbox.com/s/07jq88cqh8sxr7j/Kliejers%20amp%20ascii.jpg?dl=0

I would like to put matching load on the output so my swing will drop in
1/2.

Fundamental novice error... amplifier outputs should be LOW impedance
for maximum power transfer.


Mikek


What are you actually trying to accomplish? Input amplitude? Source
impedance? Gain (X3)? Load impedance?

...Jim Thompson

Sorry Jim, I responded to the wrong address.

What are you actually trying to accomplish?

Drive a Diode detector with a Maximum amplitude of 5Vrms

Input amplitude?

Max amplitude 1.67Vrms into the amp (gain stage)

Source impedance?

Not sure yet, I want to drive a diode detector, haven't figured out
which one yet.

Gain (X3)?

Yes, I have 5vrms source. 3 to 1 capacitive divider, just to limit swing
on FET gate to 1.67VRMS.
FET amp has a gain of 1X.
Gain of 3X brings me back up to 5Vrms.
It looks like diode detector is very linear between 3 Vrms and 5 Vrms input.

Load impedance?

What ever I need to drive the diode detector.

I'm thinking I may need high input Resistance DC amp to drive the meter.
I have only tested one so far and the meter pulls it away from the
linear line.

Here's a graph of the detector input/output.

https://www.dropbox.com/s/ql4lzlbbar17l3m/Diode%20detector%20graph.jpg?dl=0

Mikek



Drivel below that may help you understand what I'm doing.


Hey I now have two working detectors.
One is here, >
https://www.rf-microwave.com/uploads/diodes/a_temperature_compensated_linear_diode_detector.pdf


and the other is this, from a Boonton Probe. It is high impedance and
may need an amp to drive a meter. I need to check that.
Ok checked it, when driving the meter it deviates further from a
linear line. That is a 109K Load when driving the meter.
The Boonton probe has better linearity on the low end, But it has
BAT62 diodes where the upper circuit has 1n34A.


BOONTON PROBE
1/8W CF 1/4W CC Low noise double
100 ohm 330 ohm shielded cable
5% 10%
+---|<|----/\/\/----#----/\/\/-----------> out -
| | 2
1n5F | diode ---
600V? | 1n0F --- Cable End
| Cer | S
<----||----# #--------------------> GND Probe
| Cer |
1n0F ---
| diode ---
| | 1
+---|>|----/\/\/----#----/\/\/-----------> out +
5% 10%
100 ohm 330 ohm
1/8W CF 1/4W CC




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[Benderthe.evilrobot]

"amdx" <nojunk@knology.net> wrote in message
newsctdej$tfg$1@dont-email.me...

I have the following amp.
It originally had a 12V supply voltage, In an effort to get a larger swing
on the output, I raised that to 24V.
I now get 12.5Vpp on the output, I want to maximize the output signal.
A gain of 3 will work for my circuit.
What changes can I make to maximize the output swing.
The input is at maximum before distortion is seen.

https://www.dropbox.com/s/07jq88cqh8sxr7j/Kliejers%20amp%20ascii.jpg?dl=0

I would like to put matching load on the output so my swing will drop in
1/2.

A casc-ode amplifier might improve swing, but it has high output impedance
and uses 2 transistors.

The grounded base section gives no current gain, so that has to be done by
the common emitter - but the grounded base section has to be able to carry
that current.


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[David Eather]

On Mon, 17 Apr 2017 07:07:12 +1000, Jim Thompson
<To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:

On Sat, 15 Apr 2017 10:18:32 -0500, amdx <nojunk@knology.net> wrote:

I have the following amp.
It originally had a 12V supply voltage, In an effort to get a larger
swing on the output, I raised that to 24V.
I now get 12.5Vpp on the output, I want to maximize the output signal.
A gain of 3 will work for my circuit.
What changes can I make to maximize the output swing.
The input is at maximum before distortion is seen.

https://www.dropbox.com/s/07jq88cqh8sxr7j/Kliejers%20amp%20ascii.jpg?dl=0

I would like to put matching load on the output so my swing will drop in
1/2.

Fundamental novice error... amplifier outputs should be LOW impedance
for maximum power transfer.

actually for maximum power transfer the amp output impedance should be
equal to next stages input impedance. If the amplifier has a low impedance
it results im maximum efficiency not power transfer

 

[Jim Thompson]

On Tue, 18 Apr 2017 11:11:03 +1000, "David Eather" <eather@tpg.com.au>
wrote:

On Mon, 17 Apr 2017 07:07:12 +1000, Jim Thompson
To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:

On Sat, 15 Apr 2017 10:18:32 -0500, amdx <nojunk@knology.net> wrote:

I have the following amp.
It originally had a 12V supply voltage, In an effort to get a larger
swing on the output, I raised that to 24V.
I now get 12.5Vpp on the output, I want to maximize the output signal.
A gain of 3 will work for my circuit.
What changes can I make to maximize the output swing.
The input is at maximum before distortion is seen.

https://www.dropbox.com/s/07jq88cqh8sxr7j/Kliejers%20amp%20ascii.jpg?dl=0

I would like to put matching load on the output so my swing will drop in
1/2.

Fundamental novice error... amplifier outputs should be LOW impedance
for maximum power transfer.




actually for maximum power transfer the amp output impedance should be
equal to next stages input impedance. If the amplifier has a low impedance
it results im maximum efficiency not power transfer

Really?

Care to demonstrate that ?>:-}

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| STV, Queen Creek, AZ 85142 Skype: skypeanalog | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

Thinking outside the box... producing elegant solutions.

 

[George Herold]

On Monday, April 17, 2017 at 10:15:35 PM UTC-4, Jim Thompson wrote:

On Tue, 18 Apr 2017 11:11:03 +1000, "David Eather" <eather@tpg.com.au
wrote:

On Mon, 17 Apr 2017 07:07:12 +1000, Jim Thompson
To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:

On Sat, 15 Apr 2017 10:18:32 -0500, amdx <nojunk@knology.net> wrote:

I have the following amp.
It originally had a 12V supply voltage, In an effort to get a larger
swing on the output, I raised that to 24V.
I now get 12.5Vpp on the output, I want to maximize the output signal.
A gain of 3 will work for my circuit.
What changes can I make to maximize the output swing.
The input is at maximum before distortion is seen.

https://www.dropbox.com/s/07jq88cqh8sxr7j/Kliejers%20amp%20ascii.jpg?dl=0

I would like to put matching load on the output so my swing will drop in
1/2.

Fundamental novice error... amplifier outputs should be LOW impedance
for maximum power transfer.




actually for maximum power transfer the amp output impedance should be
equal to next stages input impedance. If the amplifier has a low impedance
it results im maximum efficiency not power transfer

Really?

Care to demonstrate that ?>:-}

I think that's right, but who gives a rat's ass about power
transfer. I want maximum signal! (voltage or current) I mean,
there's hardly any power transfer into a fet opamp. Are you
supposed to hang giga ohms on the input?

George H.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| STV, Queen Creek, AZ 85142 Skype: skypeanalog | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

Thinking outside the box... producing elegant solutions.

 

[amdx]

On 4/18/2017 8:03 AM, George Herold wrote:

On Monday, April 17, 2017 at 10:15:35 PM UTC-4, Jim Thompson wrote:
On Tue, 18 Apr 2017 11:11:03 +1000, "David Eather" <eather@tpg.com.au
wrote:

On Mon, 17 Apr 2017 07:07:12 +1000, Jim Thompson
To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:

On Sat, 15 Apr 2017 10:18:32 -0500, amdx <nojunk@knology.net> wrote:

I have the following amp.
It originally had a 12V supply voltage, In an effort to get a larger
swing on the output, I raised that to 24V.
I now get 12.5Vpp on the output, I want to maximize the output signal.
A gain of 3 will work for my circuit.
What changes can I make to maximize the output swing.
The input is at maximum before distortion is seen.

https://www.dropbox.com/s/07jq88cqh8sxr7j/Kliejers%20amp%20ascii.jpg?dl=0

I would like to put matching load on the output so my swing will drop in
1/2.

Fundamental novice error... amplifier outputs should be LOW impedance
for maximum power transfer.




actually for maximum power transfer the amp output impedance should be
equal to next stages input impedance. If the amplifier has a low impedance
it results im maximum efficiency not power transfer

Really?

Care to demonstrate that ?>:-}

I think that's right, but who gives a rat's ass about power
transfer. I want maximum signal! (voltage or current) I mean,
there's hardly any power transfer into a fet opamp. Are you
supposed to hang giga ohms on the input?

George H.

I think the discussion is about the output resistor on the Gain
amplifier. I'm driving a diode detector with it.
So far, I have built my detectors with a 68 ohm across the input
paralleled by the rest of the circuit to give close to 50 ohms. Then I'm
driving it with a 50 ohms source. I was looking for maximum swing into a
diode detector.
I have two detectors, one built with Bat62 diodes and one with two
different germanium diodes of unknown part number. (pulled from old pcb's)
Wouldn't you know it, the circuit with unknown diodes out preforms
the Bat 62 circuit, in my initial tests at 1MHz.
Here's a link to a graph comparing the two circuit outputs to a linear line.
> https://www.dropbox.com/s/kv7lvt8z84fvmf6/Diode%20Detector%20graph%201N34A%20and%20Bat62.jpg?dl=0
This is driving the meter, the load does change the line.
I'm wondering if having different characteristics between the two
diodes happened to coincide to make the curve fit better to a straight line?
I also wonder if changing the value of one of th 4.7k resistors could
improve the curve.
I'm building an amp to increase the output of my SigGen, so I can
test the detector up to 5Vrms output. I expect most usage of the
detector between 3V and 5V input. (it has a limit of 3V now)
Mikek





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[Tim Wescott]

On Tue, 18 Apr 2017 11:11:03 +1000, David Eather wrote:

On Mon, 17 Apr 2017 07:07:12 +1000, Jim Thompson
To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:

On Sat, 15 Apr 2017 10:18:32 -0500, amdx <nojunk@knology.net> wrote:

I have the following amp.
It originally had a 12V supply voltage, In an effort to get a larger
swing on the output, I raised that to 24V.
I now get 12.5Vpp on the output, I want to maximize the output
signal.
A gain of 3 will work for my circuit.
What changes can I make to maximize the output swing.
The input is at maximum before distortion is seen.

https://www.dropbox.com/s/07jq88cqh8sxr7j/Kliejers%20amp%20ascii.jpg?
dl=0

I would like to put matching load on the output so my swing will drop
in 1/2.

Fundamental novice error... amplifier outputs should be LOW impedance
for maximum power transfer.




actually for maximum power transfer the amp output impedance should be
equal to next stages input impedance. If the amplifier has a low
impedance it results im maximum efficiency not power transfer

So, I have a 50 ohm load, a +12V supply, and I build an amplifier that
can do 12Vp-p open-circuit, and has a 50 ohm output impedance. Working
into 50 ohms, it has a 6Vp-p output. For a sine-wave signal, that works
out to 90mW.

Contrast that with the same load and p-p limits, but an amplifier with
zero ohms output impedance. That one can put 12Vp-p into the load, or
360mW.

You're saying that 90mW is bigger than 360mW?

--
Tim Wescott
Control systems, embedded software and circuit design
I'm looking for work! See my website if you're interested
http://www.wescottdesign.com

 

[Jim Thompson]

On Tue, 18 Apr 2017 11:21:38 -0500, Tim Wescott <tim@seemywebsite.com>
wrote:

On Tue, 18 Apr 2017 11:11:03 +1000, David Eather wrote:

On Mon, 17 Apr 2017 07:07:12 +1000, Jim Thompson
To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:

On Sat, 15 Apr 2017 10:18:32 -0500, amdx <nojunk@knology.net> wrote:

I have the following amp.
It originally had a 12V supply voltage, In an effort to get a larger
swing on the output, I raised that to 24V.
I now get 12.5Vpp on the output, I want to maximize the output
signal.
A gain of 3 will work for my circuit.
What changes can I make to maximize the output swing.
The input is at maximum before distortion is seen.

https://www.dropbox.com/s/07jq88cqh8sxr7j/Kliejers%20amp%20ascii.jpg?
dl=0

I would like to put matching load on the output so my swing will drop
in 1/2.

Fundamental novice error... amplifier outputs should be LOW impedance
for maximum power transfer.




actually for maximum power transfer the amp output impedance should be
equal to next stages input impedance. If the amplifier has a low
impedance it results im maximum efficiency not power transfer

So, I have a 50 ohm load, a +12V supply, and I build an amplifier that
can do 12Vp-p open-circuit, and has a 50 ohm output impedance. Working
into 50 ohms, it has a 6Vp-p output. For a sine-wave signal, that works
out to 90mW.

Contrast that with the same load and p-p limits, but an amplifier with
zero ohms output impedance. That one can put 12Vp-p into the load, or
360mW.

You're saying that 90mW is bigger than 360mW?

See...

<http://www.analog-innovations.com/SED/Source_Load_Matching.pdf>

It's a common error with the school-book-only crowd >:-}

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| STV, Queen Creek, AZ 85142 Skype: skypeanalog | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

Thinking outside the box... producing elegant solutions.

 

[George Herold]

On Tuesday, April 18, 2017 at 12:21:45 PM UTC-4, Tim Wescott wrote:

On Tue, 18 Apr 2017 11:11:03 +1000, David Eather wrote:

On Mon, 17 Apr 2017 07:07:12 +1000, Jim Thompson
To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:

On Sat, 15 Apr 2017 10:18:32 -0500, amdx <nojunk@knology.net> wrote:

I have the following amp.
It originally had a 12V supply voltage, In an effort to get a larger
swing on the output, I raised that to 24V.
I now get 12.5Vpp on the output, I want to maximize the output
signal.
A gain of 3 will work for my circuit.
What changes can I make to maximize the output swing.
The input is at maximum before distortion is seen.

https://www.dropbox.com/s/07jq88cqh8sxr7j/Kliejers%20amp%20ascii.jpg?
dl=0

I would like to put matching load on the output so my swing will drop
in 1/2.

Fundamental novice error... amplifier outputs should be LOW impedance
for maximum power transfer.




actually for maximum power transfer the amp output impedance should be
equal to next stages input impedance. If the amplifier has a low
impedance it results im maximum efficiency not power transfer

So, I have a 50 ohm load, a +12V supply, and I build an amplifier that
can do 12Vp-p open-circuit, and has a 50 ohm output impedance. Working
into 50 ohms, it has a 6Vp-p output. For a sine-wave signal, that works
out to 90mW.

Contrast that with the same load and p-p limits, but an amplifier with
zero ohms output impedance. That one can put 12Vp-p into the load, or
360mW.

You're saying that 90mW is bigger than 360mW?

I think the argument (problem) usually starts with some output
impedance. (Physics types always start with a battery and the
internal battery resistance.) And then asks for which load is there
a maximum of power transferred from the device to the load. So if you
had 50 ohm Z-out for which load do you get maximum power?
It's a silly argument. (And sets me off, every time I hear it.)

George H.

--
Tim Wescott
Control systems, embedded software and circuit design
I'm looking for work! See my website if you're interested
http://www.wescottdesign.com

 

[Tim Wescott]

On Tue, 18 Apr 2017 10:21:20 -0700, George Herold wrote:

On Tuesday, April 18, 2017 at 12:21:45 PM UTC-4, Tim Wescott wrote:
On Tue, 18 Apr 2017 11:11:03 +1000, David Eather wrote:

On Mon, 17 Apr 2017 07:07:12 +1000, Jim Thompson
To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:

On Sat, 15 Apr 2017 10:18:32 -0500, amdx <nojunk@knology.net> wrote:

I have the following amp.
It originally had a 12V supply voltage, In an effort to get a
larger swing on the output, I raised that to 24V.
I now get 12.5Vpp on the output, I want to maximize the output
signal.
A gain of 3 will work for my circuit.
What changes can I make to maximize the output swing.
The input is at maximum before distortion is seen.

https://www.dropbox.com/s/07jq88cqh8sxr7j/Kliejers%20amp%
20ascii.jpg?
dl=0

I would like to put matching load on the output so my swing will
drop in 1/2.

Fundamental novice error... amplifier outputs should be LOW
impedance for maximum power transfer.




actually for maximum power transfer the amp output impedance should
be equal to next stages input impedance. If the amplifier has a low
impedance it results im maximum efficiency not power transfer

So, I have a 50 ohm load, a +12V supply, and I build an amplifier that
can do 12Vp-p open-circuit, and has a 50 ohm output impedance. Working
into 50 ohms, it has a 6Vp-p output. For a sine-wave signal, that
works out to 90mW.

Contrast that with the same load and p-p limits, but an amplifier with
zero ohms output impedance. That one can put 12Vp-p into the load, or
360mW.

You're saying that 90mW is bigger than 360mW?

I think the argument (problem) usually starts with some output
impedance. (Physics types always start with a battery and the internal
battery resistance.) And then asks for which load is there a maximum of
power transferred from the device to the load. So if you had 50 ohm
Z-out for which load do you get maximum power?
It's a silly argument. (And sets me off, every time I hear it.)

There are times when impedance matching is important -- but for the most
part impedance matching isn't the best thing to do. Even in a radio
receiver, the best SNR is often achieved at some input impedance that
does _not_ match the impedance of the line seen by the receiver.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

I'm looking for work -- see my website!

 

[George Herold]

On Tuesday, April 18, 2017 at 1:54:15 PM UTC-4, Tim Wescott wrote:

On Tue, 18 Apr 2017 10:21:20 -0700, George Herold wrote:

On Tuesday, April 18, 2017 at 12:21:45 PM UTC-4, Tim Wescott wrote:
On Tue, 18 Apr 2017 11:11:03 +1000, David Eather wrote:

On Mon, 17 Apr 2017 07:07:12 +1000, Jim Thompson
To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:

On Sat, 15 Apr 2017 10:18:32 -0500, amdx <nojunk@knology.net> wrote:

I have the following amp.
It originally had a 12V supply voltage, In an effort to get a
larger swing on the output, I raised that to 24V.
I now get 12.5Vpp on the output, I want to maximize the output
signal.
A gain of 3 will work for my circuit.
What changes can I make to maximize the output swing.
The input is at maximum before distortion is seen.

https://www.dropbox.com/s/07jq88cqh8sxr7j/Kliejers%20amp%
20ascii.jpg?
dl=0

I would like to put matching load on the output so my swing will
drop in 1/2.

Fundamental novice error... amplifier outputs should be LOW
impedance for maximum power transfer.




actually for maximum power transfer the amp output impedance should
be equal to next stages input impedance. If the amplifier has a low
impedance it results im maximum efficiency not power transfer

So, I have a 50 ohm load, a +12V supply, and I build an amplifier that
can do 12Vp-p open-circuit, and has a 50 ohm output impedance. Working
into 50 ohms, it has a 6Vp-p output. For a sine-wave signal, that
works out to 90mW.

Contrast that with the same load and p-p limits, but an amplifier with
zero ohms output impedance. That one can put 12Vp-p into the load, or
360mW.

You're saying that 90mW is bigger than 360mW?

I think the argument (problem) usually starts with some output
impedance. (Physics types always start with a battery and the internal
battery resistance.) And then asks for which load is there a maximum of
power transferred from the device to the load. So if you had 50 ohm
Z-out for which load do you get maximum power?
It's a silly argument. (And sets me off, every time I hear it.)

There are times when impedance matching is important -- but for the most
part impedance matching isn't the best thing to do. Even in a radio
receiver, the best SNR is often achieved at some input impedance that
does _not_ match the impedance of the line seen by the receiver.

I'm not sure about radio receivers. Somewhere in there I think the antenna
is doing some sort of impedance matching.

Going out on a limb, I think you need impedance matching when you are
interested in energy (power) and not just the signal (amplitude) and don't
have any gain available.

So; microwave horns, trumpet horns, ultra sound transmitters/receivers,
AR coating on optics... there's probably some mechanical examples...?
George H.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

I'm looking for work -- see my website!

 

[Jim Thompson]

On Tue, 18 Apr 2017 11:37:35 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:

On Tuesday, April 18, 2017 at 1:54:15 PM UTC-4, Tim Wescott wrote:
On Tue, 18 Apr 2017 10:21:20 -0700, George Herold wrote:

On Tuesday, April 18, 2017 at 12:21:45 PM UTC-4, Tim Wescott wrote:
On Tue, 18 Apr 2017 11:11:03 +1000, David Eather wrote:

On Mon, 17 Apr 2017 07:07:12 +1000, Jim Thompson
To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:

On Sat, 15 Apr 2017 10:18:32 -0500, amdx <nojunk@knology.net> wrote:

I have the following amp.
It originally had a 12V supply voltage, In an effort to get a
larger swing on the output, I raised that to 24V.
I now get 12.5Vpp on the output, I want to maximize the output
signal.
A gain of 3 will work for my circuit.
What changes can I make to maximize the output swing.
The input is at maximum before distortion is seen.

https://www.dropbox.com/s/07jq88cqh8sxr7j/Kliejers%20amp%
20ascii.jpg?
dl=0

I would like to put matching load on the output so my swing will
drop in 1/2.

Fundamental novice error... amplifier outputs should be LOW
impedance for maximum power transfer.




actually for maximum power transfer the amp output impedance should
be equal to next stages input impedance. If the amplifier has a low
impedance it results im maximum efficiency not power transfer

So, I have a 50 ohm load, a +12V supply, and I build an amplifier that
can do 12Vp-p open-circuit, and has a 50 ohm output impedance. Working
into 50 ohms, it has a 6Vp-p output. For a sine-wave signal, that
works out to 90mW.

Contrast that with the same load and p-p limits, but an amplifier with
zero ohms output impedance. That one can put 12Vp-p into the load, or
360mW.

You're saying that 90mW is bigger than 360mW?

I think the argument (problem) usually starts with some output
impedance. (Physics types always start with a battery and the internal
battery resistance.) And then asks for which load is there a maximum of
power transferred from the device to the load. So if you had 50 ohm
Z-out for which load do you get maximum power?
It's a silly argument. (And sets me off, every time I hear it.)

There are times when impedance matching is important -- but for the most
part impedance matching isn't the best thing to do. Even in a radio
receiver, the best SNR is often achieved at some input impedance that
does _not_ match the impedance of the line seen by the receiver.


I'm not sure about radio receivers. Somewhere in there I think the antenna
is doing some sort of impedance matching.

Of course, the antenna impedance is involved. But, keep in mind,
there are best impedance for best SNR and best impedance for best
power transfer... and quite often they are NOT equal.

Going out on a limb, I think you need impedance matching when you are
interested in energy (power) and not just the signal (amplitude) and don't
have any gain available.

So; microwave horns, trumpet horns, ultra sound transmitters/receivers,
AR coating on optics... there's probably some mechanical examples...?
George H.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| STV, Queen Creek, AZ 85142 Skype: skypeanalog | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

Thinking outside the box... producing elegant solutions.

 

[Jeroen Belleman]

On 18/04/17 20:37, George Herold wrote:

On Tuesday, April 18, 2017 at 1:54:15 PM UTC-4, Tim Wescott wrote:
On Tue, 18 Apr 2017 10:21:20 -0700, George Herold wrote:

On Tuesday, April 18, 2017 at 12:21:45 PM UTC-4, Tim Wescott wrote:
On Tue, 18 Apr 2017 11:11:03 +1000, David Eather wrote:

On Mon, 17 Apr 2017 07:07:12 +1000, Jim Thompson
To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:

On Sat, 15 Apr 2017 10:18:32 -0500, amdx <nojunk@knology.net> wrote:

I have the following amp.
It originally had a 12V supply voltage, In an effort to get a
larger swing on the output, I raised that to 24V.
I now get 12.5Vpp on the output, I want to maximize the output
signal.
A gain of 3 will work for my circuit.
What changes can I make to maximize the output swing.
The input is at maximum before distortion is seen.

https://www.dropbox.com/s/07jq88cqh8sxr7j/Kliejers%20amp%
20ascii.jpg?
dl=0

I would like to put matching load on the output so my swing will
drop in 1/2.

Fundamental novice error... amplifier outputs should be LOW
impedance for maximum power transfer.




actually for maximum power transfer the amp output impedance should
be equal to next stages input impedance. If the amplifier has a low
impedance it results im maximum efficiency not power transfer

So, I have a 50 ohm load, a +12V supply, and I build an amplifier that
can do 12Vp-p open-circuit, and has a 50 ohm output impedance. Working
into 50 ohms, it has a 6Vp-p output. For a sine-wave signal, that
works out to 90mW.

Contrast that with the same load and p-p limits, but an amplifier with
zero ohms output impedance. That one can put 12Vp-p into the load, or
360mW.

You're saying that 90mW is bigger than 360mW?

I think the argument (problem) usually starts with some output
impedance. (Physics types always start with a battery and the internal
battery resistance.) And then asks for which load is there a maximum of
power transferred from the device to the load. So if you had 50 ohm
Z-out for which load do you get maximum power?
It's a silly argument. (And sets me off, every time I hear it.)

There are times when impedance matching is important -- but for the most
part impedance matching isn't the best thing to do. Even in a radio
receiver, the best SNR is often achieved at some input impedance that
does _not_ match the impedance of the line seen by the receiver.


I'm not sure about radio receivers. Somewhere in there I think the antenna
is doing some sort of impedance matching.

Going out on a limb, I think you need impedance matching when you are
interested in energy (power) and not just the signal (amplitude) and don't
have any gain available.

So; microwave horns, trumpet horns, ultra sound transmitters/receivers,
AR coating on optics... there's probably some mechanical examples...?
George H.

Sure, gears and levers, the middle ear.

In the case of SNR optimization, it often happens that the noise and
signal have different source impedances, and the best SNR match would
then be off w.r.t. the maximum power match.

Maximum power matching is useful for antennas and various transducers,
but it mostly doesn't matter after the first amplifier stage.
Of course, inserting resistors to equal source and load impedances
is just plain silly, although there may be other reasons to do so
anyway.

Jeroen Belleman

 

[Ralph Mowery]

In article <8vadncKBRZhdz2vFnZ2dnUU7-fOdnZ2d@giganews.com>,
seemywebsite@myfooter.really says...

There are times when impedance matching is important -- but for the most
part impedance matching isn't the best thing to do. Even in a radio
receiver, the best SNR is often achieved at some input impedance that
does _not_ match the impedance of the line seen by the receiver.

For receiver only, the noise figure and SNR and impedance matching can
get tricky. While the NF of the receiver is almost never where the
impedance is matched to the transmission line. Then if the impedance is
not matched closely you can loose more signal in the transmission line
if there is very much loss in the transmission line.

 

[Tim Wescott]

On Tue, 18 Apr 2017 11:47:40 -0700, Jim Thompson wrote:

On Tue, 18 Apr 2017 11:37:35 -0700 (PDT), George Herold
gherold@teachspin.com> wrote:

On Tuesday, April 18, 2017 at 1:54:15 PM UTC-4, Tim Wescott wrote:
On Tue, 18 Apr 2017 10:21:20 -0700, George Herold wrote:

On Tuesday, April 18, 2017 at 12:21:45 PM UTC-4, Tim Wescott wrote:
On Tue, 18 Apr 2017 11:11:03 +1000, David Eather wrote:

On Mon, 17 Apr 2017 07:07:12 +1000, Jim Thompson
To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:

On Sat, 15 Apr 2017 10:18:32 -0500, amdx <nojunk@knology.net
wrote:

I have the following amp.
It originally had a 12V supply voltage, In an effort to get a
larger swing on the output, I raised that to 24V.
I now get 12.5Vpp on the output, I want to maximize the
output signal.
A gain of 3 will work for my circuit.
What changes can I make to maximize the output swing.
The input is at maximum before distortion is seen.

https://www.dropbox.com/s/07jq88cqh8sxr7j/Kliejers%20amp%
20ascii.jpg?
dl=0

I would like to put matching load on the output so my swing
will drop in 1/2.

Fundamental novice error... amplifier outputs should be LOW
impedance for maximum power transfer.




actually for maximum power transfer the amp output impedance
should be equal to next stages input impedance. If the amplifier
has a low impedance it results im maximum efficiency not power
transfer

So, I have a 50 ohm load, a +12V supply, and I build an amplifier
that can do 12Vp-p open-circuit, and has a 50 ohm output impedance.
Working into 50 ohms, it has a 6Vp-p output. For a sine-wave
signal, that works out to 90mW.

Contrast that with the same load and p-p limits, but an amplifier
with zero ohms output impedance. That one can put 12Vp-p into the
load, or 360mW.

You're saying that 90mW is bigger than 360mW?

I think the argument (problem) usually starts with some output
impedance. (Physics types always start with a battery and the
internal battery resistance.) And then asks for which load is there
a maximum of power transferred from the device to the load. So if
you had 50 ohm Z-out for which load do you get maximum power?
It's a silly argument. (And sets me off, every time I hear it.)

There are times when impedance matching is important -- but for the
most part impedance matching isn't the best thing to do. Even in a
radio receiver, the best SNR is often achieved at some input impedance
that does _not_ match the impedance of the line seen by the receiver.


I'm not sure about radio receivers. Somewhere in there I think the
antenna is doing some sort of impedance matching.

Of course, the antenna impedance is involved. But, keep in mind,
there are best impedance for best SNR and best impedance for best power
transfer... and quite often they are NOT equal.

Yup. That's what I was trying to say.

There are techniques to _make_ them equal, using transformers in the
feedback path of your LNA, but AFAIK that measure doesn't improve SNR --
it just reduces the reflection back from the receiver.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

I'm looking for work -- see my website!

 

[George Herold]

On Tuesday, April 18, 2017 at 3:12:10 PM UTC-4, Jeroen Belleman wrote:

On 18/04/17 20:37, George Herold wrote:
On Tuesday, April 18, 2017 at 1:54:15 PM UTC-4, Tim Wescott wrote:
On Tue, 18 Apr 2017 10:21:20 -0700, George Herold wrote:

On Tuesday, April 18, 2017 at 12:21:45 PM UTC-4, Tim Wescott wrote:
On Tue, 18 Apr 2017 11:11:03 +1000, David Eather wrote:

On Mon, 17 Apr 2017 07:07:12 +1000, Jim Thompson
To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:

On Sat, 15 Apr 2017 10:18:32 -0500, amdx <nojunk@knology.net> wrote:

I have the following amp.
It originally had a 12V supply voltage, In an effort to get a
larger swing on the output, I raised that to 24V.
I now get 12.5Vpp on the output, I want to maximize the output
signal.
A gain of 3 will work for my circuit.
What changes can I make to maximize the output swing.
The input is at maximum before distortion is seen.

https://www.dropbox.com/s/07jq88cqh8sxr7j/Kliejers%20amp%
20ascii.jpg?
dl=0

I would like to put matching load on the output so my swing will
drop in 1/2.

Fundamental novice error... amplifier outputs should be LOW
impedance for maximum power transfer.




actually for maximum power transfer the amp output impedance should
be equal to next stages input impedance. If the amplifier has a low
impedance it results im maximum efficiency not power transfer

So, I have a 50 ohm load, a +12V supply, and I build an amplifier that
can do 12Vp-p open-circuit, and has a 50 ohm output impedance. Working
into 50 ohms, it has a 6Vp-p output. For a sine-wave signal, that
works out to 90mW.

Contrast that with the same load and p-p limits, but an amplifier with
zero ohms output impedance. That one can put 12Vp-p into the load, or
360mW.

You're saying that 90mW is bigger than 360mW?

I think the argument (problem) usually starts with some output
impedance. (Physics types always start with a battery and the internal
battery resistance.) And then asks for which load is there a maximum of
power transferred from the device to the load. So if you had 50 ohm
Z-out for which load do you get maximum power?
It's a silly argument. (And sets me off, every time I hear it.)

There are times when impedance matching is important -- but for the most
part impedance matching isn't the best thing to do. Even in a radio
receiver, the best SNR is often achieved at some input impedance that
does _not_ match the impedance of the line seen by the receiver.


I'm not sure about radio receivers. Somewhere in there I think the antenna
is doing some sort of impedance matching.

Going out on a limb, I think you need impedance matching when you are
interested in energy (power) and not just the signal (amplitude) and don't
have any gain available.

So; microwave horns, trumpet horns, ultra sound transmitters/receivers,
AR coating on optics... there's probably some mechanical examples...?
George H.

Sure, gears and levers, the middle ear.

Yes, (duh) and pulleys.. (my mind went to the
capstan (for pulling up anchors)).
What's the electrical equivalent of the ratchet and pawl?
(I've got my answer.)
George H.

In the case of SNR optimization, it often happens that the noise and
signal have different source impedances, and the best SNR match would
then be off w.r.t. the maximum power match.

Maximum power matching is useful for antennas and various transducers,
but it mostly doesn't matter after the first amplifier stage.
Of course, inserting resistors to equal source and load impedances
is just plain silly, although there may be other reasons to do so
anyway.

Jeroen Belleman

 

[amdx]

On 4/18/2017 6:58 PM, George Herold wrote:

On Tuesday, April 18, 2017 at 3:12:10 PM UTC-4, Jeroen Belleman wrote:
On 18/04/17 20:37, George Herold wrote:
On Tuesday, April 18, 2017 at 1:54:15 PM UTC-4, Tim Wescott wrote:
On Tue, 18 Apr 2017 10:21:20 -0700, George Herold wrote:

On Tuesday, April 18, 2017 at 12:21:45 PM UTC-4, Tim Wescott wrote:
On Tue, 18 Apr 2017 11:11:03 +1000, David Eather wrote:

On Mon, 17 Apr 2017 07:07:12 +1000, Jim Thompson
To-Email-Use-The-Envelope-Icon@on-my-web-site.com> wrote:

On Sat, 15 Apr 2017 10:18:32 -0500, amdx <nojunk@knology.net> wrote:

I have the following amp.
It originally had a 12V supply voltage, In an effort to get a
larger swing on the output, I raised that to 24V.
I now get 12.5Vpp on the output, I want to maximize the output
signal.
A gain of 3 will work for my circuit.
What changes can I make to maximize the output swing.
The input is at maximum before distortion is seen.

https://www.dropbox.com/s/07jq88cqh8sxr7j/Kliejers%20amp%
20ascii.jpg?
dl=0

I would like to put matching load on the output so my swing will
drop in 1/2.

Fundamental novice error... amplifier outputs should be LOW
impedance for maximum power transfer.




actually for maximum power transfer the amp output impedance should
be equal to next stages input impedance. If the amplifier has a low
impedance it results im maximum efficiency not power transfer

So, I have a 50 ohm load, a +12V supply, and I build an amplifier that
can do 12Vp-p open-circuit, and has a 50 ohm output impedance. Working
into 50 ohms, it has a 6Vp-p output. For a sine-wave signal, that
works out to 90mW.

Contrast that with the same load and p-p limits, but an amplifier with
zero ohms output impedance. That one can put 12Vp-p into the load, or
360mW.

You're saying that 90mW is bigger than 360mW?

I think the argument (problem) usually starts with some output
impedance. (Physics types always start with a battery and the internal
battery resistance.) And then asks for which load is there a maximum of
power transferred from the device to the load. So if you had 50 ohm
Z-out for which load do you get maximum power?
It's a silly argument. (And sets me off, every time I hear it.)

There are times when impedance matching is important -- but for the most
part impedance matching isn't the best thing to do. Even in a radio
receiver, the best SNR is often achieved at some input impedance that
does _not_ match the impedance of the line seen by the receiver.


I'm not sure about radio receivers. Somewhere in there I think the antenna
is doing some sort of impedance matching.

Going out on a limb, I think you need impedance matching when you are
interested in energy (power) and not just the signal (amplitude) and don't
have any gain available.

So; microwave horns, trumpet horns, ultra sound transmitters/receivers,
AR coating on optics... there's probably some mechanical examples...?
George H.

Sure, gears and levers, the middle ear.
Yes, (duh) and pulleys.. (my mind went to the
capstan (for pulling up anchors)).
What's the electrical equivalent of the ratchet and pawl?
(I've got my answer.)

Sample and hold?
Mikek

George H.

In the case of SNR optimization, it often happens that the noise and
signal have different source impedances, and the best SNR match would
then be off w.r.t. the maximum power match.

Maximum power matching is useful for antennas and various transducers,
but it mostly doesn't matter after the first amplifier stage.
Of course, inserting resistors to equal source and load impedances
is just plain silly, although there may be other reasons to do so
anyway.

Jeroen Belleman

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