I think this works.
https://www.dropbox.com/scl/fi/kbfnta8idc9f8o3ww6zt6/Current_Sink_3.jpg?rlkey=06hl3vdh8eataurw8cf5l7dor&raw=1
I think this works.
https://www.dropbox.com/scl/fi/kbfnta8idc9f8o3ww6zt6/Current_Sink_3.jpg?rlkey=06hl3vdh8eataurw8cf5l7dor&raw=1
I think this works.
https://www.dropbox.com/scl/fi/kbfnta8idc9f8o3ww6zt6/Current_Sink_3.jpg?rlkey=06hl3vdh8eataurw8cf5l7dor&raw=1
I think this works.
https://www.dropbox.com/scl/fi/kbfnta8idc9f8o3ww6zt6/Current_Sink_3.jpg?rlkey=06hl3vdh8eataurw8cf5l7dor&raw=1
https://www.dropbox.com/scl/fi/kbfnta8idc9f8o3ww6zt6/Current_Sink_3.jpg?r lkey=06hl3vdh8eataurw8cf5l7dor&raw=1
piglet <erichpwagner@hotmail.com> wrote:
https://www.dropbox.com/scl/fi/kbfnta8idc9f8o3ww6zt6/Current_Sink_3.jpg?r
lkey=06hl3vdh8eataurw8cf5l7dor&raw=1
I see no advantage over conventional methods, in fact, several disadvantages.
Why waste our time on ideas that have no merit?
On Wednesday, December 20, 2023 at 10:53:15?PM UTC-5, John Larkin wrote:
I think this works.
https://www.dropbox.com/scl/fi/kbfnta8idc9f8o3ww6zt6/Current_Sink_3.jpg?rlkey=06hl3vdh8eataurw8cf5l7dor&raw=1
That goes back a ways. You'll find examples of that in the older opamp cookbooks circa 1970s-1980s -ish. Disadvantage is it requires a single OA pkg, also I has to be in excess of OA supply current. Other than that it's a perfectly good circuit.
On a sunny day (Wed, 20 Dec 2023 19:52:11 -0800) it happened John Larkin ><jl@997PotHill.com> wrote in <sgd7oipj183untsh2m5fa6qgle7i5v8ste@4ax.com>:
I think this works.
https://www.dropbox.com/scl/fi/kbfnta8idc9f8o3ww6zt6/Current_Sink_3.jpg?rlkey=06hl3vdh8eataurw8cf5l7dor&raw=1
Cool!
PS
there are of course severe limitations with that circuit.
Often one need very low currents, the own current draw of the opamp or >whatever gets then in the way
And sometimes one needs a lot of current, more than the opamp can supply.
So one then uses for example a 'transistor'
https://en.m.wikipedia.org/wiki/Transistor
the transistor / MOSFET then is driven by the amplifier.
http://www.learningaboutelectronics.com/Articles/Current-source-circuit.php
If it just needs to be sort of a constant current a simple JFET with source resistor and gate to ground will do.
like J2 here:
https://panteltje.online/panteltje/scope_tv/diagram.jpg
I think this works.
https://www.dropbox.com/scl/fi/kbfnta8idc9f8o3ww6zt6/Current_Sink_3.jpg?rlkey=06hl3vdh8eataurw8cf5l7dor&raw=1
Fred Bloggs wrote:
John Larkin wrote:
I think this works.
https://www.dropbox.com/scl/fi/kbfnta8idc9f8o3ww6zt6/Current_Sink_3.jpg?rlke
That goes back a ways. You'll find examples of that in the older opamp cookboo
I hadn't seen it before, but I guess most simple circuits have been discovered before, somewhere. What's relatively new is fabulous cheap low-current RRIO opamps.
torsdag den 21. december 2023 kl. 04.53.15 UTC+1 skrev John Larkin:
I think this works.
https://www.dropbox.com/scl/fi/kbfnta8idc9f8o3ww6zt6/Current_Sink_3.jpg?rlkey=06hl3vdh8eataurw8cf5l7dor&raw=1
https://www.edn.com/op-amp-can-source-or-sink-current/
On Thu, 21 Dec 2023 12:07:58 -0000 (UTC), Mike Monett VE3BTI
<spamme@not.com> wrote:
piglet <erichpwagner@hotmail.com> wrote:
https://www.dropbox.com/scl/fi/kbfnta8idc9f8o3ww6zt6/Current_Sink_3.jpg?r >>> lkey=06hl3vdh8eataurw8cf5l7dor&raw=1
I see no advantage over conventional methods, in fact, several disadvantages.
Why waste our time on ideas that have no merit?
You and Sloman poison ideas at birth. There's a simple explanation.
I actually have a use for this.
Sorry to waste your valuable time. How much do you charge per hour, to
read usenet posts?
On Thu, 21 Dec 2023 11:43:58 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
On a sunny day (Wed, 20 Dec 2023 19:52:11 -0800) it happened John Larkin
<jl@997PotHill.com> wrote in <sgd7oipj183untsh2m5fa6qgle7i5v8ste@4ax.com>: >>
I think this works.
https://www.dropbox.com/scl/fi/kbfnta8idc9f8o3ww6zt6/Current_Sink_3.jpg?rlkey=06hl3vdh8eataurw8cf5l7dor&raw=1
Cool!
PS
there are of course severe limitations with that circuit.
As with every circuit. You'd need help from an engineer to make it
work.
Often one need very low currents, the own current draw of the opamp or
whatever gets then in the way
And sometimes one needs a lot of current, more than the opamp can supply.
So one then uses for example a 'transistor'
https://en.m.wikipedia.org/wiki/Transistor
the transistor / MOSFET then is driven by the amplifier.
http://www.learningaboutelectronics.com/Articles/Current-source-circuit.php >>
If it just needs to be sort of a constant current a simple JFET with source resistor and gate to ground will do.
like J2 here:
https://panteltje.online/panteltje/scope_tv/diagram.jpg
I want a precision controlled current sink.
Jfets have a huge range of Idss. Some parts are specified 10:1. The
Supertex depletion mosfets are much better.
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