Speaking of high speed opamps

[George Herold]

I'm putting together an order for some fast opamps. I've not used
these yet. So..
1.) If any have some gotcha, you know about please let me know.

The circuit will be an intermediate gain stage.*
(So some preamp ahead of it.)
I am going to do a string of inverting amps, 1 k ohm in,
10k FB, with 3 or 4 stages. (10^3 or 10^4 gain total)
For the first 2-3 stages I dont care so much about slew rate,
I'd like low offset voltage, but there will have to be some
AC coupling, so not crucial.
So for the first opamps I was going to order the OPA1611(12)
And maybe the LT1222 or LT1226.
The LT parts are nice 'cause I can get a dip.
For the last stage (or two) of gain I'm ordering the
AD828 (dual) (AD818 is single).
(450 V/us slew rate.)
useful 'guesstimate', 2*pi*freq*V_peak = SR.

Thoughts, comments, criticism? all welcome.

George H.


*oh ~30V supply rail, VFB? I'm hoping for a few MHz over all BW.

 

[George Herold]

On Friday, March 6, 2020 at 4:22:28 PM UTC-5, John Larkin wrote:

On Fri, 6 Mar 2020 13:09:05 -0800 (PST), George Herold
ggherold@gmail.com> wrote:

I'm putting together an order for some fast opamps. I've not used
these yet. So..
1.) If any have some gotcha, you know about please let me know.

The circuit will be an intermediate gain stage.*
(So some preamp ahead of it.)
I am going to do a string of inverting amps, 1 k ohm in,
10k FB, with 3 or 4 stages. (10^3 or 10^4 gain total)
For the first 2-3 stages I dont care so much about slew rate,
I'd like low offset voltage, but there will have to be some
AC coupling, so not crucial.
So for the first opamps I was going to order the OPA1611(12)
And maybe the LT1222 or LT1226.
The LT parts are nice 'cause I can get a dip.
For the last stage (or two) of gain I'm ordering the
AD828 (dual) (AD818 is single).
(450 V/us slew rate.)
useful 'guesstimate', 2*pi*freq*V_peak = SR.

Thoughts, comments, criticism? all welcome.

George H.


*oh ~30V supply rail, VFB? I'm hoping for a few MHz over all BW.

450 v/us is only sorta fast. You can do 10x or even 20x better if you
need to.

TBH I'm a little afraid of fast amps.. Dang thing will oscifllate
and I'll never see 'em on my slowish 'scope.

The faster amps are usually current-mode, and have awful DC specs. And
input impedance drops as frequency goes up. They steal a lot of power
from their inputs.

Right. I've only used one CFB opamp. How do you slow those things
down if they are going too fast? (more FB resistance?)

TI makes some nice fast current-mode amps with decently large supply
voltages.
If I can get ~5MHz overall that would be fine.

George H.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

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

 

[John Larkin]

On Fri, 6 Mar 2020 13:09:05 -0800 (PST), George Herold
<ggherold@gmail.com> wrote:

I'm putting together an order for some fast opamps. I've not used
these yet. So..
1.) If any have some gotcha, you know about please let me know.

The circuit will be an intermediate gain stage.*
(So some preamp ahead of it.)
I am going to do a string of inverting amps, 1 k ohm in,
10k FB, with 3 or 4 stages. (10^3 or 10^4 gain total)
For the first 2-3 stages I dont care so much about slew rate,
I'd like low offset voltage, but there will have to be some
AC coupling, so not crucial.
So for the first opamps I was going to order the OPA1611(12)
And maybe the LT1222 or LT1226.
The LT parts are nice 'cause I can get a dip.
For the last stage (or two) of gain I'm ordering the
AD828 (dual) (AD818 is single).
(450 V/us slew rate.)
useful 'guesstimate', 2*pi*freq*V_peak = SR.

Thoughts, comments, criticism? all welcome.

George H.


*oh ~30V supply rail, VFB? I'm hoping for a few MHz over all BW.

450 v/us is only sorta fast. You can do 10x or even 20x better if you
need to.

The faster amps are usually current-mode, and have awful DC specs. And
input impedance drops as frequency goes up. They steal a lot of power
from their inputs.

TI makes some nice fast current-mode amps with decently large supply
voltages.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

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

 

[John Larkin]

On Fri, 6 Mar 2020 13:33:22 -0800 (PST), George Herold
<ggherold@gmail.com> wrote:

On Friday, March 6, 2020 at 4:22:28 PM UTC-5, John Larkin wrote:
On Fri, 6 Mar 2020 13:09:05 -0800 (PST), George Herold
ggherold@gmail.com> wrote:

I'm putting together an order for some fast opamps. I've not used
these yet. So..
1.) If any have some gotcha, you know about please let me know.

The circuit will be an intermediate gain stage.*
(So some preamp ahead of it.)
I am going to do a string of inverting amps, 1 k ohm in,
10k FB, with 3 or 4 stages. (10^3 or 10^4 gain total)
For the first 2-3 stages I dont care so much about slew rate,
I'd like low offset voltage, but there will have to be some
AC coupling, so not crucial.
So for the first opamps I was going to order the OPA1611(12)
And maybe the LT1222 or LT1226.
The LT parts are nice 'cause I can get a dip.
For the last stage (or two) of gain I'm ordering the
AD828 (dual) (AD818 is single).
(450 V/us slew rate.)
useful 'guesstimate', 2*pi*freq*V_peak = SR.

Thoughts, comments, criticism? all welcome.

George H.


*oh ~30V supply rail, VFB? I'm hoping for a few MHz over all BW.

450 v/us is only sorta fast. You can do 10x or even 20x better if you
need to.
TBH I'm a little afraid of fast amps.. Dang thing will oscifllate
and I'll never see 'em on my slowish 'scope.

The faster amps are usually current-mode, and have awful DC specs. And
input impedance drops as frequency goes up. They steal a lot of power
from their inputs.

Right. I've only used one CFB opamp. How do you slow those things
down if they are going too fast? (more FB resistance?)

Yes. Gain-bandwidth falls as Rf increases.

--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

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

 

[Winfield Hill]

George Herold wrote...

I'm putting together an order for some fast opamps.

The x-Chapters, Tables 4x.2 (VFB, 4-pages), and 4x.3
(CFB), with accompanying discussions, pages 304-323.


--
Thanks,
- Win

 

[Rick C]

On Friday, March 6, 2020 at 4:09:11 PM UTC-5, George Herold wrote:

I'm putting together an order for some fast opamps. I've not used
these yet. So..
1.) If any have some gotcha, you know about please let me know.

The circuit will be an intermediate gain stage.*
(So some preamp ahead of it.)
I am going to do a string of inverting amps, 1 k ohm in,
10k FB, with 3 or 4 stages. (10^3 or 10^4 gain total)
For the first 2-3 stages I dont care so much about slew rate,
I'd like low offset voltage, but there will have to be some
AC coupling, so not crucial.
So for the first opamps I was going to order the OPA1611(12)
And maybe the LT1222 or LT1226.
The LT parts are nice 'cause I can get a dip.
For the last stage (or two) of gain I'm ordering the
AD828 (dual) (AD818 is single).
(450 V/us slew rate.)
useful 'guesstimate', 2*pi*freq*V_peak = SR.

Thoughts, comments, criticism? all welcome.

I'm much less familiar with this field than most here, but if you want high gain and in the front end you need low noise, isn't that what instrumentation amps are about?

My brother inherited a design from the US Army for a biomonitor which uses the signal from fish coughing as an indicator of pollution in the water. One version of the system uses standard rack equipment for the ADC. A version that is intended to be used in the field with the cage being a bit removed from the rack has an instrumentation amp board located on the rack. When I looked into replacing the obsolete amp in that design I found there are a number of amp chips available all of which seem to meet your requirements... well, except for maybe the overall bandwidth, and can replace all three front end chips. I don't know if they work up to a few MHz. BTW, how "few" are you looking for? Is 2 enough, 6 too many? Extra points if you can tell me what that question is from.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

 

[Rick C]

On Friday, March 6, 2020 at 11:51:07 PM UTC-5, boB wrote:

On Fri, 6 Mar 2020 18:02:47 -0800 (PST), Rick C
gnuarm.deletethisbit@gmail.com> wrote:

On Friday, March 6, 2020 at 4:09:11 PM UTC-5, George Herold wrote:
I'm putting together an order for some fast opamps. I've not used
these yet. So..
1.) If any have some gotcha, you know about please let me know.

The circuit will be an intermediate gain stage.*
(So some preamp ahead of it.)
I am going to do a string of inverting amps, 1 k ohm in,
10k FB, with 3 or 4 stages. (10^3 or 10^4 gain total)
For the first 2-3 stages I dont care so much about slew rate,
I'd like low offset voltage, but there will have to be some
AC coupling, so not crucial.
So for the first opamps I was going to order the OPA1611(12)
And maybe the LT1222 or LT1226.
The LT parts are nice 'cause I can get a dip.
For the last stage (or two) of gain I'm ordering the
AD828 (dual) (AD818 is single).
(450 V/us slew rate.)
useful 'guesstimate', 2*pi*freq*V_peak = SR.

Thoughts, comments, criticism? all welcome.

I'm much less familiar with this field than most here, but if you want high gain and in the front end you need low noise, isn't that what instrumentation amps are about?

My brother inherited a design from the US Army for a biomonitor which uses the signal from fish coughing as an indicator of pollution in the water.

coughing fishes ?!? How do they cover their mouths to prevent
getting all the other sea creatures wet ?


Wow ! Who woulda' thunk it ?!?

First Google hit....

"A fish does indeed cough, just not the way you think it coughs. ...
No, a fish only coughs when their ventilation cycle is interrupted for
some reason. The only time this occurs is when a fish has to cleanse
its gills."

Yeah, seems fish are uniquely sensitive to pollutants. If they start coughing, you may not know what is bothering them, but you know it's time to stop drinking the water.

They use the system in New York and at least once the fish detected something in the water at about the same time a report showed up that there had been a petroleum spill some miles upriver.

I think my brother will do very well with this system. Not only is there money to be made in selling the systems, but the fish have to be swapped out periodically and there is a continuing revenue stream on this service aspect of the business. Sell them the razors AND the blades.

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209

 

[boB]

On Fri, 6 Mar 2020 18:02:47 -0800 (PST), Rick C
<gnuarm.deletethisbit@gmail.com> wrote:

On Friday, March 6, 2020 at 4:09:11 PM UTC-5, George Herold wrote:
I'm putting together an order for some fast opamps. I've not used
these yet. So..
1.) If any have some gotcha, you know about please let me know.

The circuit will be an intermediate gain stage.*
(So some preamp ahead of it.)
I am going to do a string of inverting amps, 1 k ohm in,
10k FB, with 3 or 4 stages. (10^3 or 10^4 gain total)
For the first 2-3 stages I dont care so much about slew rate,
I'd like low offset voltage, but there will have to be some
AC coupling, so not crucial.
So for the first opamps I was going to order the OPA1611(12)
And maybe the LT1222 or LT1226.
The LT parts are nice 'cause I can get a dip.
For the last stage (or two) of gain I'm ordering the
AD828 (dual) (AD818 is single).
(450 V/us slew rate.)
useful 'guesstimate', 2*pi*freq*V_peak = SR.

Thoughts, comments, criticism? all welcome.

I'm much less familiar with this field than most here, but if you want high gain and in the front end you need low noise, isn't that what instrumentation amps are about?

My brother inherited a design from the US Army for a biomonitor which uses the signal from fish coughing as an indicator of pollution in the water.

coughing fishes ?!? How do they cover their mouths to prevent
getting all the other sea creatures wet ?


Wow ! Who woulda' thunk it ?!?

First Google hit....

"A fish does indeed cough, just not the way you think it coughs. ...
No, a fish only coughs when their ventilation cycle is interrupted for
some reason. The only time this occurs is when a fish has to cleanse
its gills."


>One version of the system uses standard rack equipment for the ADC. A version that is intended to be used in the field with the cage being a bit removed from the rack has an instrumentation amp board located on the rack. When I looked into replacing the obsolete amp in that design I found there are a number of amp chips available all of which seem to meet your requirements... well, except for maybe the overall bandwidth, and can replace all three front end chips. I don't know if they work up to a few MHz. BTW, how "few" are you looking for? Is 2 enough, 6 too many? Extra points if you can tell me what that question is from.

 

Crayfish have been "working" in St.-Petersburg since December 2005.
http://www.vodokanal.spb.ru/en/vodosnabzhenie/biomonitoring/crayfish/

 

[Tom Del Rosso]

Rick C wrote:

On Friday, March 6, 2020 at 11:51:07 PM UTC-5, boB wrote:
On Fri, 6 Mar 2020 18:02:47 -0800 (PST), Rick C
gnuarm.deletethisbit@gmail.com> wrote:
My brother inherited a design from the US Army for a biomonitor
which uses the signal from fish coughing as an indicator of
pollution in the water.

"A fish does indeed cough, just not the way you think it coughs. ...
No, a fish only coughs when their ventilation cycle is interrupted
for some reason. The only time this occurs is when a fish has to
cleanse its gills."

Yeah, seems fish are uniquely sensitive to pollutants. If they start
coughing, you may not know what is bothering them, but you know it's
time to stop drinking the water.

They use the system in New York and at least once the fish detected
something in the water at about the same time a report showed up that
there had been a petroleum spill some miles upriver.

But what did the Army have to do with it? Testing foreign water sources
for soldiers in the field to drink?

 

[Rick C]

On Saturday, March 7, 2020 at 7:22:58 AM UTC-5, Tom Del Rosso wrote:

Rick C wrote:
On Friday, March 6, 2020 at 11:51:07 PM UTC-5, boB wrote:
On Fri, 6 Mar 2020 18:02:47 -0800 (PST), Rick C
gnuarm.deletethisbit@gmail.com> wrote:
My brother inherited a design from the US Army for a biomonitor
which uses the signal from fish coughing as an indicator of
pollution in the water.

"A fish does indeed cough, just not the way you think it coughs. ...
No, a fish only coughs when their ventilation cycle is interrupted
for some reason. The only time this occurs is when a fish has to
cleanse its gills."

Yeah, seems fish are uniquely sensitive to pollutants. If they start
coughing, you may not know what is bothering them, but you know it's
time to stop drinking the water.

They use the system in New York and at least once the fish detected
something in the water at about the same time a report showed up that
there had been a petroleum spill some miles upriver.

But what did the Army have to do with it? Testing foreign water sources
for soldiers in the field to drink?

The US Army did the initial development and prototype design. They wanted someone to commercialize and produce the device. The documentation was not in a good state and some key portion of the code were lacking source. I think most of that is straightened out now as they are shipping systems.

The Army also has need for such systems to verify they are not polluting water ways at their US bases. So it's for our protection too. Do you know what they do at Fort Detrick? I recently read the commander of Fort Detrick gave a press conference on Corona Virus. Kinda like in prisons. You don't want anything unauthorized getting in or out.

--

Rick C.

-- Get 1,000 miles of free Supercharging
-- Tesla referral code - https://ts.la/richard11209

 

[George Herold]

On Friday, March 6, 2020 at 9:02:52 PM UTC-5, Rick C wrote:

On Friday, March 6, 2020 at 4:09:11 PM UTC-5, George Herold wrote:
I'm putting together an order for some fast opamps. I've not used
these yet. So..
1.) If any have some gotcha, you know about please let me know.

The circuit will be an intermediate gain stage.*
(So some preamp ahead of it.)
I am going to do a string of inverting amps, 1 k ohm in,
10k FB, with 3 or 4 stages. (10^3 or 10^4 gain total)
For the first 2-3 stages I dont care so much about slew rate,
I'd like low offset voltage, but there will have to be some
AC coupling, so not crucial.
So for the first opamps I was going to order the OPA1611(12)
And maybe the LT1222 or LT1226.
The LT parts are nice 'cause I can get a dip.
For the last stage (or two) of gain I'm ordering the
AD828 (dual) (AD818 is single).
(450 V/us slew rate.)
useful 'guesstimate', 2*pi*freq*V_peak = SR.

Thoughts, comments, criticism? all welcome.

I'm much less familiar with this field than most here, but if you want high gain and in the front end you need low noise, isn't that what instrumentation amps are about?

Yeah this is not the front end. 1 k ohm R_in inverting amp
so it starts off with 4 nV/rtHz of noise.

George H.
Oh I always think of instrument amps, when I've got some differential
signal and common mode stuff (at DC or low freq.) that I don't want.

My brother inherited a design from the US Army for a biomonitor which uses the signal from fish coughing as an indicator of pollution in the water. One version of the system uses standard rack equipment for the ADC. A version that is intended to be used in the field with the cage being a bit removed from the rack has an instrumentation amp board located on the rack. When I looked into replacing the obsolete amp in that design I found there are a number of amp chips available all of which seem to meet your requirements... well, except for maybe the overall bandwidth, and can replace all three front end chips. I don't know if they work up to a few MHz. BTW, how "few" are you looking for? Is 2 enough, 6 too many? Extra points if you can tell me what that question is from.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

 

[George Herold]

On Friday, March 6, 2020 at 8:53:20 PM UTC-5, Winfield Hill wrote:

George Herold wrote...

I'm putting together an order for some fast opamps.

The x-Chapters, Tables 4x.2 (VFB, 4-pages), and 4x.3
(CFB), with accompanying discussions, pages 304-323.
Yeah my table 4x.2 has all sorts of pencil marks on it.

So here's thing I see. All the low noise parts (v_n<~2 nV/rtHz)
have crappy slew rate... fast slew rate = more front end noise.
Is there a 'electronics' reason for that or is it maybe market
forces. (no needs low noise and slew rate)

George H.

--
Thanks,
- Win

 

On Sat, 7 Mar 2020 10:54:43 -0800 (PST), George Herold
<ggherold@gmail.com> wrote:

On Friday, March 6, 2020 at 8:53:20 PM UTC-5, Winfield Hill wrote:
George Herold wrote...

I'm putting together an order for some fast opamps.

The x-Chapters, Tables 4x.2 (VFB, 4-pages), and 4x.3
(CFB), with accompanying discussions, pages 304-323.
Yeah my table 4x.2 has all sorts of pencil marks on it.

So here's thing I see. All the low noise parts (v_n<~2 nV/rtHz)
have crappy slew rate... fast slew rate = more front end noise.
Is there a 'electronics' reason for that or is it maybe market
forces. (no needs low noise and slew rate)

High slew rate does suggest big voltage swings! So noise doesn't
matter much. In what I think is your case, only the last stage needs
big swing and high slew. Keep its gain moderate.

Current-mode opamps are inherently cruddy for noise and DC
performance. They are deceptive in that they steal a lot of power from
the input signal as speeds go up; that's one way to get slew rate!

They get hot too, which doesn't help.



--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"

 

[Phil Hobbs]

On 2020-03-06 16:09, George Herold wrote:

I'm putting together an order for some fast opamps. I've not used
these yet. So..
1.) If any have some gotcha, you know about please let me know.

The circuit will be an intermediate gain stage.*
(So some preamp ahead of it.)
I am going to do a string of inverting amps, 1 k ohm in,
10k FB, with 3 or 4 stages. (10^3 or 10^4 gain total)
For the first 2-3 stages I dont care so much about slew rate,
I'd like low offset voltage, but there will have to be some
AC coupling, so not crucial.
So for the first opamps I was going to order the OPA1611(12)
And maybe the LT1222 or LT1226.
The LT parts are nice 'cause I can get a dip.
For the last stage (or two) of gain I'm ordering the
AD828 (dual) (AD818 is single).
(450 V/us slew rate.)
useful 'guesstimate', 2*pi*freq*V_peak = SR.

Thoughts, comments, criticism? all welcome.

George H.


*oh ~30V supply rail, VFB? I'm hoping for a few MHz over all BW.

For applications that aren't too noise sensitive, I'm a fan of
LT6171/6172.

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

 

[Phil Hobbs]

On 2020-03-07 13:54, George Herold wrote:

On Friday, March 6, 2020 at 8:53:20 PM UTC-5, Winfield Hill wrote:
George Herold wrote...

I'm putting together an order for some fast opamps.

The x-Chapters, Tables 4x.2 (VFB, 4-pages), and 4x.3
(CFB), with accompanying discussions, pages 304-323.
Yeah my table 4x.2 has all sorts of pencil marks on it.

So here's thing I see. All the low noise parts (v_n<~2 nV/rtHz)
have crappy slew rate... fast slew rate = more front end noise.
Is there a 'electronics' reason for that or is it maybe market
forces. (no needs low noise and slew rate)

In classical op amps with pole-splitting compensation, the GBW and slew
rate are related by

SR ~= 0.3*GBW.

IIRC this is in National AN4, which talks about the op amp as the
universal analogue circuit.

In that architecture, improving the slew rate requires reducing the
transconductance of the front end, e.g. by putting in emitter resistors.
This contributes additional noise in fast bipolar devices. The
naturally lower transconductance of JFETs allowed a better tradeoff of
noise vs. slew BITD.

Modern architectures are more complicated, and I don't know too much
about the details, but you still have a diff pair in the first stage!

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 Sat, 7 Mar 2020 18:56:50 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-03-07 13:54, George Herold wrote:
On Friday, March 6, 2020 at 8:53:20 PM UTC-5, Winfield Hill wrote:
George Herold wrote...

I'm putting together an order for some fast opamps.

The x-Chapters, Tables 4x.2 (VFB, 4-pages), and 4x.3
(CFB), with accompanying discussions, pages 304-323.
Yeah my table 4x.2 has all sorts of pencil marks on it.

So here's thing I see. All the low noise parts (v_n<~2 nV/rtHz)
have crappy slew rate... fast slew rate = more front end noise.
Is there a 'electronics' reason for that or is it maybe market
forces. (no needs low noise and slew rate)

In classical op amps with pole-splitting compensation, the GBW and slew
rate are related by

SR ~= 0.3*GBW.

IIRC this is in National AN4, which talks about the op amp as the
universal analogue circuit.

In that architecture, improving the slew rate requires reducing the
transconductance of the front end, e.g. by putting in emitter resistors.
This contributes additional noise in fast bipolar devices. The
naturally lower transconductance of JFETs allowed a better tradeoff of
noise vs. slew BITD.

Modern architectures are more complicated, and I don't know too much
about the details, but you still have a diff pair in the first stage!

Cheers

Phil Hobbs

Some bipolar opamp has the usual diff pair, but if the input error
gets too big, hundreds of millivolts or something, some extra
transistors kick in to help. Like a current-mode amp, that loads the
input signal more to get current to process. That in turn opens up
possibilities for creative spec-sheet writing.




--

John Larkin Highland Technology, Inc

The cork popped merrily, and Lord Peter rose to his feet.
"Bunter", he said, "I give you a toast. The triumph of Instinct over Reason"

 

[Winfield Hill]

Phil Hobbs wrote...

For applications that aren't too noise sensitive,
I'm a fan of LT6171/6172.

LM6171, LM6172.


--
Thanks,
- Win

 

[Don Kuenz]

plastcontrol.ru@gmail.com wrote:

Crayfish have been "working" in St.-Petersburg since December 2005.
http://www.vodokanal.spb.ru/en/vodosnabzhenie/biomonitoring/crayfish/

Bravo! Take care of the Earth's creatures and the Earth will take care
of you.

Nature taught me that it takes a spider to fight a spider. Here's a
description of my shop's symbiotic spider "workforce:"

http://michael2.home.crcomp.net/biology/charlenescobweb/index.php



And here's a new page about coping with COVID-19 (Coronavirus):

https://crcomp.net/biology/covid19

Thank you,

--
Don Kuenz KB7RPU
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.

 

[Don Kuenz]

plastcontrol.ru@gmail.com wrote:

Crayfish have been "working" in St.-Petersburg since December 2005.
http://www.vodokanal.spb.ru/en/vodosnabzhenie/biomonitoring/crayfish/

Bravo! Take care of the Earth's creatures and the Earth will take care
of you.

Nature taught me that it takes a spider to fight a spider. Here's a
description of my shop's symbiotic spider "workforce:"

https://crcomp.net/biology/charlenescobweb

(Note: link fixed.)



And here's a new page about coping with COVID-19 (Coronavirus):

https://crcomp.net/biology/covid19

Thank you,

--
Don Kuenz KB7RPU
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.