OT: milestone, the x-Chapters

W

Winfield Hill

Guest
Last night we handed over finished latex and
eps files, for AoE The x-Chapters, to our
long-suffering editor at CUP.

Amazing stuff * went in during the last 10 days,
plus I get to make submissions and corrections
for maybe three more weeks, while the files
are being processed. The draft pdf version
has over 650 pages.

* Hundreds of explorations and explanations
of exotic engineering stuff you need to know.
* A dozen varied examples of using power MOSFETs
to solve difficult linear-circuit problems.
* A neat TIA amplifier with an 8-decade dynamic
range, 12-bit precision, not a log converter!
Example use: a starlight to sunlight digitizer.
* A true DC transformer. Keep your extra energy.
* Control your piezo with charge, not voltage.
* 1.2kV HV amplifier, with DC-to-1MHz range.
* 100V 5A DC-10MHz 1000V/us power amplifier.
* More light, pulse your LED at 200 amps.
* Fast 1.5kV 2pF floating current source.
* Hundreds of other cool things, too tired to
type, need sleep.


--
Thanks,
- Win
 
On 24 Jun 2019 03:38:40 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

Last night we handed over finished latex and
eps files, for AoE The x-Chapters, to our
long-suffering editor at CUP.

Amazing stuff * went in during the last 10 days,
plus I get to make submissions and corrections
for maybe three more weeks, while the files
are being processed. The draft pdf version
has over 650 pages.

* Hundreds of explorations and explanations
of exotic engineering stuff you need to know.
* A dozen varied examples of using power MOSFETs
to solve difficult linear-circuit problems.
* A neat TIA amplifier with an 8-decade dynamic
range, 12-bit precision, not a log converter!
Example use: a starlight to sunlight digitizer.
* A true DC transformer. Keep your extra energy.
* Control your piezo with charge, not voltage.
* 1.2kV HV amplifier, with DC-to-1MHz range.
* 100V 5A DC-10MHz 1000V/us power amplifier.
* More light, pulse your LED at 200 amps.
* Fast 1.5kV 2pF floating current source.
* Hundreds of other cool things, too tired to
type, need sleep.
Click to expand...

Congrats, I'm looking forward to purchasing a copy. Do you know the
(very approximate) publication timeline?
 
Steve Goldstein wrote...
Winfield Hill wrote:

Last night we handed over finished latex and
eps files, for AoE The x-Chapters, to our
long-suffering editor at CUP.

Congrats, I'm looking forward to purchasing a copy.
Do you know the publication timeline?
Click to expand...

Yes, everything is tuned for a Dec 1st release.


--
Thanks,
- Win
 
On Monday, June 24, 2019 at 11:01:42 AM UTC-4, Winfield Hill wrote:
Winfield Hill wrote...

* A neat TIA amplifier with an 8-decade dynamic
range, 12-bit precision, not a log converter!
Example use: a starlight to sunlight digitizer.

Let's see, 10V out, precision feedback resistor,
10uV input opamp voltage offset, 6-decade range,
with 100% error at the bottom. Raise output to
100V with amp, feedback resistor there, 7-decades.
How get 8 decades with 1% precision (10-decades)?

Maximum current 5mA, minimum FS = 50pA, for 1%
max Ioffset 0.5pA, check!

Maximum Voffset 100V/10^10 = 0.01uV, no way!
Change range resistors, not allowed? Sheesh!
We reveal the secret, a clever, easy-to-use
solution, but it wasn't our idea!

Hint, starlight to sunlight circuit, 15 parts:
three opamps, eight Rs, two Cs, and two JFETs.
The input opamp is an LMP7701, Vos = 200uV Ib.
One S2387–33R detector. Readout, 12-bit ADC in
uP. 60pA (10% is 6pA) to 3mA, 5 x 10^8 range.
Can you do it?
Well only if I'm allowed to change feedback R's. :^)
Click to expand...

So what's the trick?

Nice to hear this is in the works. I'll put it on my Xmas wish list.

George H.
--
Thanks,
- Win
Click to expand...
 
On 24 Jun 2019 08:01:23 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

Winfield Hill wrote...

* A neat TIA amplifier with an 8-decade dynamic
range, 12-bit precision, not a log converter!
Example use: a starlight to sunlight digitizer.

Let's see, 10V out, precision feedback resistor,
10uV input opamp voltage offset, 6-decade range,
with 100% error at the bottom. Raise output to
100V with amp, feedback resistor there, 7-decades.
How get 8 decades with 1% precision (10-decades)?

Maximum current 5mA, minimum FS = 50pA, for 1%
max Ioffset 0.5pA, check!

Maximum Voffset 100V/10^10 = 0.01uV, no way!
Change range resistors, not allowed? Sheesh!
We reveal the secret, a clever, easy-to-use
solution, but it wasn't our idea!

Hint, starlight to sunlight circuit, 15 parts:
three opamps, eight Rs, two Cs, and two JFETs.
The input opamp is an LMP7701, Vos = 200uV Ib.
One S2387–33R detector. Readout, 12-bit ADC in
uP. 60pA (10% is 6pA) to 3mA, 5 x 10^8 range.
Can you do it?
Click to expand...

Progressive amp saturation? That's fun.

You can dump both ends of a photodiode into two TIAs, with different
gains. There are also other uses for that idea.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics
 
Winfield Hill wrote...
* A neat TIA amplifier with an 8-decade dynamic
range, 12-bit precision, not a log converter!
Example use: a starlight to sunlight digitizer.
Click to expand...

Let's see, 10V out, precision feedback resistor,
10uV input opamp voltage offset, 6-decade range,
with 100% error at the bottom. Raise output to
100V with amp, feedback resistor there, 7-decades.
How get 8 decades with 1% precision (10-decades)?

Maximum current 5mA, minimum FS = 50pA, for 1%
max Ioffset 0.5pA, check!

Maximum Voffset 100V/10^10 = 0.01uV, no way!
Change range resistors, not allowed? Sheesh!
We reveal the secret, a clever, easy-to-use
solution, but it wasn't our idea!

Hint, starlight to sunlight circuit, 15 parts:
three opamps, eight Rs, two Cs, and two JFETs.
The input opamp is an LMP7701, Vos = 200uV Ib.
One S2387–33R detector. Readout, 12-bit ADC in
uP. 60pA (10% is 6pA) to 3mA, 5 x 10^8 range.
Can you do it?


--
Thanks,
- Win
 
John Larkin wrote...
Winfield Hill wrote:
Winfield Hill wrote...

* A neat TIA amplifier with an 8-decade dynamic
range, 12-bit precision, not a log converter!
Example use: a starlight to sunlight digitizer.

Let's see, 10V out, precision feedback resistor,
10uV input opamp voltage offset, 6-decade range,
with 100% error at the bottom. Raise output to
100V with amp, feedback resistor there, 7-decades.
How get 8 decades with 1% precision (10-decades)?

Maximum current 5mA, minimum FS = 50pA, for 1%
max Ioffset 0.5pA, check!

Maximum Voffset 100V/10^10 = 0.01uV, no way!
Change range resistors, not allowed? Sheesh!
We reveal the secret, a clever, easy-to-use
solution, but it wasn't our idea!

Hint, starlight to sunlight circuit, 15 parts:
three opamps, eight Rs, two Cs, and two JFETs.
The input opamp is an LMP7701, Vos = 200uV Ib.
One S2387–33R detector. Readout, 12-bit ADC in
uP. 60pA (10% is 6pA) to 3mA, 5 x 10^8 range.
Can you do it?

You can dump both ends of a photodiode into two
TIAs, with different gains. There are also other
uses for that idea.
Click to expand...

Yes, that's cute, but this one needs more range.


--
Thanks,
- Win
 
On a sunny day (24 Jun 2019 09:45:42 -0700) it happened Winfield Hill
<winfieldhill@yahoo.com> wrote in <qequnm0f60@drn.newsguy.com>:

George Herold wrote...

On June 24, 2019, Winfield Hill wrote:

Hint, starlight to sunlight circuit, 15 parts:
three opamps, eight Rs, two Cs, and two JFETs.
The input opamp is an LMP7701, Vos =3D 200uV Ib.
One S2387-33R detector. Readout, 12-bit ADC in
uP. 60pA (10% is 6pA) to 3mA, 5 x 10^8 range.
Can you do it?

Well only if I'm allowed to change feedback R's. :^)

Nope, only one input stage allowed, and it takes
all the photo-current. You can play games with
the feedback resistor, but you're not allowed to
disconnect one and connect another, with a switch,
because that'd interrupt the measurement.

Sometimes, once you know something is possible,
you can figure out how to do it. But I don't
think I could have solved this puzzle, even with
that knowledge. Once I saw it done, I had to
think carefully to understand it. But others
are smarter than me, and may get the answer.
Click to expand...

You would not be using a JFET as AGC element?
 
George Herold wrote...
On June 24, 2019, Winfield Hill wrote:

Hint, starlight to sunlight circuit, 15 parts:
three opamps, eight Rs, two Cs, and two JFETs.
The input opamp is an LMP7701, Vos =3D 200uV Ib.
One S2387-33R detector. Readout, 12-bit ADC in
uP. 60pA (10% is 6pA) to 3mA, 5 x 10^8 range.
Can you do it?

Well only if I'm allowed to change feedback R's. :^)
Click to expand...

Nope, only one input stage allowed, and it takes
all the photo-current. You can play games with
the feedback resistor, but you're not allowed to
disconnect one and connect another, with a switch,
because that'd interrupt the measurement.

Sometimes, once you know something is possible,
you can figure out how to do it. But I don't
think I could have solved this puzzle, even with
that knowledge. Once I saw it done, I had to
think carefully to understand it. But others
are smarter than me, and may get the answer.


--
Thanks,
- Win
 
On 24 Jun 2019 09:32:31 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

John Larkin wrote...

Winfield Hill wrote:
Winfield Hill wrote...

* A neat TIA amplifier with an 8-decade dynamic
range, 12-bit precision, not a log converter!
Example use: a starlight to sunlight digitizer.

Let's see, 10V out, precision feedback resistor,
10uV input opamp voltage offset, 6-decade range,
with 100% error at the bottom. Raise output to
100V with amp, feedback resistor there, 7-decades.
How get 8 decades with 1% precision (10-decades)?

Maximum current 5mA, minimum FS = 50pA, for 1%
max Ioffset 0.5pA, check!

Maximum Voffset 100V/10^10 = 0.01uV, no way!
Change range resistors, not allowed? Sheesh!
We reveal the secret, a clever, easy-to-use
solution, but it wasn't our idea!

Hint, starlight to sunlight circuit, 15 parts:
three opamps, eight Rs, two Cs, and two JFETs.
The input opamp is an LMP7701, Vos = 200uV Ib.
One S2387–33R detector. Readout, 12-bit ADC in
uP. 60pA (10% is 6pA) to 3mA, 5 x 10^8 range.
Can you do it?

You can dump both ends of a photodiode into two
TIAs, with different gains. There are also other
uses for that idea.

Yes, that's cute, but this one needs more range.
Click to expand...

Suppose you build a TIA with high gain. When it rails, one could
diode-couple the (former) summing point into the next, lower gain TIA.
With very good diodes of course.

Or connect the first summing point into an emitter or a fet source,
which would conduct when the TIA gives up. Similar idea.

Or use a nonlinear breakpoint thing in a TIA feedback.

What do you have against log amps?!




--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
On 6/24/19 11:01 AM, Winfield Hill wrote:
Winfield Hill wrote...

* A neat TIA amplifier with an 8-decade dynamic
range, 12-bit precision, not a log converter!
Example use: a starlight to sunlight digitizer.

Let's see, 10V out, precision feedback resistor,
10uV input opamp voltage offset, 6-decade range,
with 100% error at the bottom. Raise output to
100V with amp, feedback resistor there, 7-decades.
How get 8 decades with 1% precision (10-decades)?

Maximum current 5mA, minimum FS = 50pA, for 1%
max Ioffset 0.5pA, check!

Maximum Voffset 100V/10^10 = 0.01uV, no way!
Change range resistors, not allowed? Sheesh!
We reveal the secret, a clever, easy-to-use
solution, but it wasn't our idea!

Hint, starlight to sunlight circuit, 15 parts:
three opamps, eight Rs, two Cs, and two JFETs.
The input opamp is an LMP7701, Vos = 200uV Ib.
One S2387–33R detector. Readout, 12-bit ADC in
uP. 60pA (10% is 6pA) to 3mA, 5 x 10^8 range.
Can you do it?
Click to expand...

Sure. Run the PD open circuit and measure the voltage. Back in 1990 I
built a beam aiming detector that I still use based on that trick. It
uses a Ge quad cell and uses two op amps to form V1-V3 and V2-V4. Two
centre-zero, edge-reading taut-band panel meters read X and Y.

It works over about four decades of photocurrent because the shunt
resistance of the Ge quad cell is the pits, but I've used it from < 400
nm to >1600 nm.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On 6/24/19 6:38 AM, Winfield Hill wrote:
Last night we handed over finished latex and
eps files, for AoE The x-Chapters, to our
long-suffering editor at CUP.

Amazing stuff * went in during the last 10 days,
plus I get to make submissions and corrections
for maybe three more weeks, while the files
are being processed. The draft pdf version
has over 650 pages.

* Hundreds of explorations and explanations
of exotic engineering stuff you need to know.
* A dozen varied examples of using power MOSFETs
to solve difficult linear-circuit problems.
* A neat TIA amplifier with an 8-decade dynamic
range, 12-bit precision, not a log converter!
Example use: a starlight to sunlight digitizer.
* A true DC transformer. Keep your extra energy.
* Control your piezo with charge, not voltage.
* 1.2kV HV amplifier, with DC-to-1MHz range.
* 100V 5A DC-10MHz 1000V/us power amplifier.
* More light, pulse your LED at 200 amps.
* Fast 1.5kV 2pF floating current source.
* Hundreds of other cool things, too tired to
type, need sleep.


Congratulations!
Click to expand...

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On 6/24/19 2:35 PM, John Larkin wrote:
On 24 Jun 2019 09:32:31 -0700, Winfield Hill <winfieldhill@yahoo.com
wrote:

John Larkin wrote...

Winfield Hill wrote:
Winfield Hill wrote...

* A neat TIA amplifier with an 8-decade dynamic
range, 12-bit precision, not a log converter!
Example use: a starlight to sunlight digitizer.

Let's see, 10V out, precision feedback resistor,
10uV input opamp voltage offset, 6-decade range,
with 100% error at the bottom. Raise output to
100V with amp, feedback resistor there, 7-decades.
How get 8 decades with 1% precision (10-decades)?

Maximum current 5mA, minimum FS = 50pA, for 1%
max Ioffset 0.5pA, check!

Maximum Voffset 100V/10^10 = 0.01uV, no way!
Change range resistors, not allowed? Sheesh!
We reveal the secret, a clever, easy-to-use
solution, but it wasn't our idea!

Hint, starlight to sunlight circuit, 15 parts:
three opamps, eight Rs, two Cs, and two JFETs.
The input opamp is an LMP7701, Vos = 200uV Ib.
One S2387–33R detector. Readout, 12-bit ADC in
uP. 60pA (10% is 6pA) to 3mA, 5 x 10^8 range.
Can you do it?

You can dump both ends of a photodiode into two
TIAs, with different gains. There are also other
uses for that idea.

Yes, that's cute, but this one needs more range.

Suppose you build a TIA with high gain. When it rails, one could
diode-couple the (former) summing point into the next, lower gain TIA.
With very good diodes of course.

Or connect the first summing point into an emitter or a fet source,
which would conduct when the TIA gives up. Similar idea.

Or use a nonlinear breakpoint thing in a TIA feedback.

What do you have against log amps?!
Click to expand...

The PD already comes with a free one . ;)

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On Monday, June 24, 2019 at 2:38:01 PM UTC-4, John Larkin wrote:
On 24 Jun 2019 09:32:31 -0700, Winfield Hill <winfieldhill@yahoo.com
wrote:

John Larkin wrote...

Winfield Hill wrote:
Winfield Hill wrote...

* A neat TIA amplifier with an 8-decade dynamic
range, 12-bit precision, not a log converter!
Example use: a starlight to sunlight digitizer.

Let's see, 10V out, precision feedback resistor,
10uV input opamp voltage offset, 6-decade range,
with 100% error at the bottom. Raise output to
100V with amp, feedback resistor there, 7-decades.
How get 8 decades with 1% precision (10-decades)?

Maximum current 5mA, minimum FS = 50pA, for 1%
max Ioffset 0.5pA, check!

Maximum Voffset 100V/10^10 = 0.01uV, no way!
Change range resistors, not allowed? Sheesh!
We reveal the secret, a clever, easy-to-use
solution, but it wasn't our idea!

Hint, starlight to sunlight circuit, 15 parts:
three opamps, eight Rs, two Cs, and two JFETs.
The input opamp is an LMP7701, Vos = 200uV Ib.
One S2387–33R detector. Readout, 12-bit ADC in
uP. 60pA (10% is 6pA) to 3mA, 5 x 10^8 range.
Can you do it?

You can dump both ends of a photodiode into two
TIAs, with different gains. There are also other
uses for that idea.

Yes, that's cute, but this one needs more range.

Suppose you build a TIA with high gain. When it rails, one could
diode-couple the (former) summing point into the next, lower gain TIA.
With very good diodes of course.

Or connect the first summing point into an emitter or a fet source,
which would conduct when the TIA gives up. Similar idea.

Or use a nonlinear breakpoint thing in a TIA feedback.

What do you have against log amps?!
Click to expand...
Build 3 TIA's, different gains, when the lowest rails you switch to the
next one?

George H.
--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
Click to expand...
 
Phil Hobbs wrote...
On 6/24/19 11:01 AM, Winfield Hill wrote:
Winfield Hill wrote...

* A neat TIA amplifier with an 8-decade dynamic
range, 12-bit precision, not a log converter!
Example use: a starlight to sunlight digitizer.

Let's see, 10V out, precision feedback resistor,
10uV input opamp voltage offset, 6-decade range,
with 100% error at the bottom. Raise output to
100V with amp, feedback resistor there, 7-decades.
How get 8 decades with 1% precision (10-decades)?

Maximum current 5mA, minimum FS = 50pA, for 1%
max Ioffset 0.5pA, check!

Maximum Voffset 100V/10^10 = 0.01uV, no way!
Change range resistors, not allowed? Sheesh!
We reveal the secret, a clever, easy-to-use
solution, but it wasn't our idea!

Hint, starlight to sunlight circuit, 15 parts:
three opamps, eight Rs, two Cs, and two JFETs.
The input opamp is an LMP7701, Vos = 200uV Ib.
One S2387–33R detector. Readout, 12-bit ADC in
uP. 60pA (10% is 6pA) to 3mA, 5 x 10^8 range.
Can you do it?

Sure. Run the PD open circuit and measure the voltage.
Click to expand...

Accurate to photocurrent, to 1% or 0.1%, no tempco?


--
Thanks,
- Win
 
Phil Hobbs wrote...
On 6/24/19 2:35 PM, John Larkin wrote:
On 24 Jun 2019, Winfield Hill wrote:
John Larkin wrote...
Winfield Hill wrote:
Winfield Hill wrote...

* A neat TIA amplifier with an 8-decade dynamic
range, 12-bit precision, not a log converter!
Example use: a starlight to sunlight digitizer.

Let's see, 10V out, precision feedback resistor,
10uV input opamp voltage offset, 6-decade range,
with 100% error at the bottom. Raise output to
100V with amp, feedback resistor there, 7-decades.
How get 8 decades with 1% precision (10-decades)?

Maximum current 5mA, minimum FS = 50pA, for 1%
max Ioffset 0.5pA, check!

Maximum Voffset 100V/10^10 = 0.01uV, no way!
Change range resistors, not allowed? Sheesh!
We reveal the secret, a clever, easy-to-use
solution, but it wasn't our idea!

Hint, starlight to sunlight circuit, 15 parts:
three opamps, eight Rs, two Cs, and two JFETs.
The input opamp is an LMP7701, Vos = 200uV Ib.
One S2387–33R detector. Readout, 12-bit ADC in
uP. 60pA (10% is 6pA) to 3mA, 5 x 10^8 range.
Can you do it?

You can dump both ends of a photodiode into two
TIAs, with different gains. There are also other
uses for that idea.

Yes, that's cute, but this one needs more range.

Suppose you build a TIA with high gain. When it rails, one could
diode-couple the (former) summing point into the next, lower gain TIA.
With very good diodes of course.

Or connect the first summing point into an emitter or a fet source,
which would conduct when the TIA gives up. Similar idea.

Or use a nonlinear breakpoint thing in a TIA feedback.

What do you have against log amps?!

The PD already comes with a free one . ;)
Click to expand...

We want 1% or 0.1% accuracy, linear, no tempco.


--
Thanks,
- Win
 
John Larkin wrote...
On 24 Jun 2019, Winfield Hill wrote:
John Larkin wrote...
Winfield Hill wrote:
Winfield Hill wrote...

* A neat TIA amplifier with an 8-decade dynamic
range, 12-bit precision, not a log converter!
Example use: a starlight to sunlight digitizer.

Let's see, 10V out, precision feedback resistor,
10uV input opamp voltage offset, 6-decade range,
with 100% error at the bottom. Raise output to
100V with amp, feedback resistor there, 7-decades.
How get 8 decades with 1% precision (10-decades)?

Maximum current 5mA, minimum FS = 50pA, for 1%
max Ioffset 0.5pA, check!

Maximum Voffset 100V/10^10 = 0.01uV, no way!
Change range resistors, not allowed? Sheesh!
We reveal the secret, a clever, easy-to-use
solution, but it wasn't our idea!

Hint, starlight to sunlight circuit, 15 parts:
three opamps, eight Rs, two Cs, and two JFETs.
The input opamp is an LMP7701, Vos = 200uV Ib.
One S2387–33R detector. Readout, 12-bit ADC in
uP. 60pA (10% is 6pA) to 3mA, 5 x 10^8 range.
Can you do it?

You can dump both ends of a photodiode into two
TIAs, with different gains. There are also other
uses for that idea.

Yes, that's cute, but this one needs more range.

Suppose you build a TIA with high gain. When it
rails, one could diode-couple the (former)
summing point into the next, lower gain TIA.
With very good diodes of course.

Or connect the first summing point into an emitter
or a fet source, which would conduct when the
TIA gives up. Similar idea.

Or use a nonlinear breakpoint thing in a TIA feedback.

What do you have against log amps?!
Click to expand...

Can't see how any of your ideas could be made
to work to 10% 1% let alone 09.1%, exactly.
Getting close maybe, but no cigar.


--
Thanks,
- Win
 
Jan Panteltje wrote...
On 24 Jun 2019, Winfield Hill wrote
George Herold wrote...
On June 24, 2019, Winfield Hill wrote:

Hint, starlight to sunlight circuit, 15 parts:
three opamps, eight Rs, two Cs, and two JFETs.
The input opamp is an LMP7701, Vos =3D 200uV Ib.
One S2387-33R detector. Readout, 12-bit ADC in
uP. 60pA (10% is 6pA) to 3mA, 5 x 10^8 range.
Can you do it?

Well only if I'm allowed to change feedback R's. :^)

Nope, only one input stage allowed, and it takes
all the photo-current. You can play games with
the feedback resistor, but you're not allowed to
disconnect one and connect another, with a switch,
because that'd interrupt the measurement.

Sometimes, once you know something is possible,
you can figure out how to do it. But I don't
think I could have solved this puzzle, even with
that knowledge. Once I saw it done, I had to
think carefully to understand it. But others
are smarter than me, and may get the answer.

You would not be using a JFET as AGC element?
Click to expand...

As an AGC, no, could that be accurate to 1% or better?


--
Thanks,
- Win
 
On Mon, 24 Jun 2019 13:54:54 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 6/24/19 11:01 AM, Winfield Hill wrote:
Winfield Hill wrote...

* A neat TIA amplifier with an 8-decade dynamic
range, 12-bit precision, not a log converter!
Example use: a starlight to sunlight digitizer.

Let's see, 10V out, precision feedback resistor,
10uV input opamp voltage offset, 6-decade range,
with 100% error at the bottom. Raise output to
100V with amp, feedback resistor there, 7-decades.
How get 8 decades with 1% precision (10-decades)?

Maximum current 5mA, minimum FS = 50pA, for 1%
max Ioffset 0.5pA, check!

Maximum Voffset 100V/10^10 = 0.01uV, no way!
Change range resistors, not allowed? Sheesh!
We reveal the secret, a clever, easy-to-use
solution, but it wasn't our idea!

Hint, starlight to sunlight circuit, 15 parts:
three opamps, eight Rs, two Cs, and two JFETs.
The input opamp is an LMP7701, Vos = 200uV Ib.
One S2387–33R detector. Readout, 12-bit ADC in
uP. 60pA (10% is 6pA) to 3mA, 5 x 10^8 range.
Can you do it?



Sure. Run the PD open circuit and measure the voltage. Back in 1990 I
built a beam aiming detector that I still use based on that trick. It
uses a Ge quad cell and uses two op amps to form V1-V3 and V2-V4. Two
centre-zero, edge-reading taut-band panel meters read X and Y.

It works over about four decades of photocurrent because the shunt
resistance of the Ge quad cell is the pits, but I've used it from < 400
nm to >1600 nm.

Cheers

Phil Hobbs
Click to expand...

Could you squirt a little current into the PD occasionally, to make a
tempco compensation measurement?


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
On 24 Jun 2019 11:51:16 -0700, Winfield Hill <winfieldhill@yahoo.com>
wrote:

John Larkin wrote...

On 24 Jun 2019, Winfield Hill wrote:
John Larkin wrote...
Winfield Hill wrote:
Winfield Hill wrote...

* A neat TIA amplifier with an 8-decade dynamic
range, 12-bit precision, not a log converter!
Example use: a starlight to sunlight digitizer.

Let's see, 10V out, precision feedback resistor,
10uV input opamp voltage offset, 6-decade range,
with 100% error at the bottom. Raise output to
100V with amp, feedback resistor there, 7-decades.
How get 8 decades with 1% precision (10-decades)?

Maximum current 5mA, minimum FS = 50pA, for 1%
max Ioffset 0.5pA, check!

Maximum Voffset 100V/10^10 = 0.01uV, no way!
Change range resistors, not allowed? Sheesh!
We reveal the secret, a clever, easy-to-use
solution, but it wasn't our idea!

Hint, starlight to sunlight circuit, 15 parts:
three opamps, eight Rs, two Cs, and two JFETs.
The input opamp is an LMP7701, Vos = 200uV Ib.
One S2387–33R detector. Readout, 12-bit ADC in
uP. 60pA (10% is 6pA) to 3mA, 5 x 10^8 range.
Can you do it?

You can dump both ends of a photodiode into two
TIAs, with different gains. There are also other
uses for that idea.

Yes, that's cute, but this one needs more range.

Suppose you build a TIA with high gain. When it
rails, one could diode-couple the (former)
summing point into the next, lower gain TIA.
With very good diodes of course.

Or connect the first summing point into an emitter
or a fet source, which would conduct when the
TIA gives up. Similar idea.

Or use a nonlinear breakpoint thing in a TIA feedback.

What do you have against log amps?!

Can't see how any of your ideas could be made
to work to 10% 1% let alone 09.1%, exactly.
Getting close maybe, but no cigar.
Click to expand...

The progressive-railing thing would be as good as the parts you care
to buy. 0.1% should be possible.

How did your guy do it?


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
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