Maker Pro
Maker Pro

simple 150uA constant current supply

P

Phil Allison

Jan 1, 1970
0
"Dave the Fucking Cunthead TROLL "
Lots of interesting stuff here thanks.
Just to clarify I have a 2 x AAA cell supply and want to drive an LED at
150uA which will be around 2V.


** Care to explain why this crucial info was NOT included at the beginning
??

Lemme guess, Dave -

YOU like to keep people in the dark and do your running around for you ?

Like any other fuckwit, narcissistic, anencephalic PITA TROLL ??

Is dat you ?


........ Phil
 
M

MooseFET

Jan 1, 1970
0
There are microscopic nanopower opamps from Linear and others. Since all
you want is nominal +/-20% , and this is the same as Vbatt ranging from
2-3V, then something simple that does not require much battery current
would be like so, total bias around 16ua, compliance should be to within
a few hundred millivolts of the rail, and you could do even better with
a PFET:
View in a fixed-width font such as Courier.
.
.
.
. BATT---+-----------+-----------.
. | | |
. | | |
. [3.9k] | [390]
. | | |
. | .----|-----------+
. | | | |
. | | |\ | |
. | '-|-\| |<
. | | >---------| 2N3904
. +--------|+/| |\
. | |/ | |
. | | |
. | | Iout
. | |
. [166k] |
. | |
. | |
. COM---+-----------+-------
.
.
.

That circuit will usually oscillate, sometimes at two different
frequencies simultaneously.

Not if you use a really-really slow op-amp. The real part of the Zout
of the op amp will be high enough to prevent the 2N3904 from tuning up
and the 2N3904 is so fast compared to the op-amp that it adds no
noticable phase shift.

If you are using a non-really slow op-amp:
Modified version:
.
.
.
. BATT---+-----------+-----------.
. | | |
. | | |
. [3.9k] | [390]
. | | |
. | .----|--+--[R]---+
. | | | ! |
. | | |\ | [C] |
. | '-|-\| ! |<
. | | >--+-[R]--| 2N3904
. +--------|+/| |\
. | |/ | |
. | | |
. | | Iout
. | |
. [166k] |
. | |
. | |
. COM---+-----------+-------
.
 
M

MooseFET

Jan 1, 1970
0
John said:
Thanks Martin but, it's not homework, I don't have any space for an
IC and this is battery powered. I can only spare about 30uA to
'generate' this supply.
There are microscopic nanopower opamps from Linear and others. Since all
you want is nominal +/-20% , and this is the same as Vbatt ranging from
2-3V, then something simple that does not require much battery current
would be like so, total bias around 16ua, compliance should be to within
a few hundred millivolts of the rail, and you could do even better with
a PFET:
View in a fixed-width font such as Courier.
.
.
.
. BATT---+-----------+-----------.
. | | |
. | | |
. [3.9k] | [390]
. | | |
. | .----|-----------+
. | | | |
. | | |\ | |
. | '-|-\| |<
. | | >---------| 2N3904
. +--------|+/| |\
. | |/ | |
. | | |
. | | Iout
. | |
. [166k] |
. | |
. | |
. COM---+-----------+-------
.
.
.
That circuit will usually oscillate, sometimes at two different
frequencies simultaneously.
John
Okay, very cool- so he needs to rectify and smooth the output <wink>, do
you have a problem with that?
Seriously, the GBW is like 25KHz...

If the opamp is very slow, as most micropower amps are, the main loop
will be stable. But the 3904 may, usually does, oscillate at a couple
hundred MHz on its own. A bit of resistance in series with the base,
33 ohms or so, will fix that. Strangely, the Zout of most opamps is
not enough to kill the Q of the base circuit.

I've found that on some of the micro power ones it is.
 
D

Dave

Jan 1, 1970
0
John Fields said:
Lots of interesting stuff here thanks.
Just to clarify I have a 2 x AAA cell supply and want to drive an LED at
150uA which will be around 2V.
The AA supply will obviously not be completely exhausted by the time there
is insufficient voltage to light the LED but the intensity needs to be
reasonably constant until then.
By the way, why do trolls despise themselves so much as indicated by the
intense anger?

---
Jeezus, what a fucking waste of time...

If, in your initial post, you'd have stated that all you wanted to do
was drive an LED at 150µA from a couple of AAA cells, then the answer
you'd have gotten back would have been pretty close to:

+--------+
| |
|+ [6200R]
BAT |
| [LED]
| |K
+--------+

and you'd probably have gotten back two or three posts instead of40.

LOL, who's the troll???

JF

The LED intensity will not be the same from 3v down to 2v IDIOT!
 
G

Geo

Jan 1, 1970
0
This needs to be discrete components rather than IC and should not involve
pulse width modulation.
The simplest form I thought of was a 3v voltage reg

Which is an IC and is excluded by your "needs to be discrete" requirement.

Geo
 
D

Dave

Jan 1, 1970
0
Geo said:
Which is an IC and is excluded by your "needs to be discrete" requirement.

Geo

Thanks for your pedantic useless contribution.
Perhaps smallest footprint might have satisfied your nit picking?
Dave
 
D

Dave

Jan 1, 1970
0
John Fields said:
John Fields said:
Lots of interesting stuff here thanks.
Just to clarify I have a 2 x AAA cell supply and want to drive an LED at
150uA which will be around 2V.
The AA supply will obviously not be completely exhausted by the time
there
is insufficient voltage to light the LED but the intensity needs to be
reasonably constant until then.
By the way, why do trolls despise themselves so much as indicated by the
intense anger?

---
Jeezus, what a fucking waste of time...

If, in your initial post, you'd have stated that all you wanted to do
was drive an LED at 150µA from a couple of AAA cells, then the answer
you'd have gotten back would have been pretty close to:

+--------+
| |
|+ [6200R]
BAT |
| [LED]
| |K
+--------+

and you'd probably have gotten back two or three posts instead of40.

LOL, who's the troll???

JF

The LED intensity will not be the same from 3v down to 2v IDIOT!

So why suggest it moron?

Other than some 20 or 30% babble on the current tolerance and some
other gobbledygook about a 3V regulator and making something from 65µA
I don't see where you said it had to be and, you inconsiderate
buffoon, why didn't you just say all you wanted to do was light an
LED in the first place?

Inconsiderate?
Why should I be considerate to you and your bumbling gimp Phil?

Plus, we got no answer to my :

"If you're not allowed to use integrated circuits, then why don't you
post the schematic for the 3V regulator you've come up with, as well
as with what's feeding it and what the load looks like?"

which, had you replied, would have gone a long way to clearing things
up.

I think Phil was pretty close on his assessment this time.

JF

Think you should rename the firm Autistic Instruments.
Seems more appropriate somehow...
 
D

Dave

Jan 1, 1970
0
Dave said:
Thanks for your pedantic useless contribution.
Perhaps smallest footprint might have satisfied your nit picking?
Dave


Dave,

You need to be a bit calmer. Geo was certainly not being pedantic, in
electronics "discrete" and an IC are certainly not the same, it's one or the
other!
 
D

Dave

Jan 1, 1970
0
John Fields said:
Hmmm...

I don't see where I suggested that at all, what I did suggest was that
you drop a volt to drive the LED at 150µA with the battery at 3V and
let the illumination tail off after that.


No you didn't.

You simply didn't think it through...then you tried to justify yourself -
what an IDIOT!

Why is it that top guys like Spehro, Bill S and others can provide helpful
excellent replies and in a generous non-confrontational manner and you wade
in with your beligerant nonsense?
Maybe it is because you are a deeply unhappy and bitter IDIOT who is hiding
a dark secret?

Are Beech and Raytheon aware of the sort of malicious noxious abuse you dish
out and the sort of dumb mistakes you make?
Are their shareholders aware?

Well if they weren't, they soon will be...

Dave
 
B

Bill Sloman

Jan 1, 1970
0
Fred Bloggs said:
Bill said:
Thanks Martin but, it's not homework, I don't have any space for an
IC and this is battery powered. I can only spare about 30uA to
'generate' this supply.

There are microscopic nanopower opamps from Linear and others. Since all
you want is nominal +/-20% , and this is the same as Vbatt ranging from
2-3V, then something simple that does not require much battery current
would be like so, total bias around 16ua, compliance should be to within
a few hundred millivolts of the rail, and you could do even better with a
PFET:


A simple asymmetric current mirror built with a dual PNP transistor - as
drawn below - or an NPN part would have much the same accuracy (depending
on the Vbe matching between the two transistors in the dual) would
probably be cheaper and would use fewer parts, and is unlikely to
oscillate.

Farnell stock four NPN and five PNP duals from NXP (was Philips) as well
as five current mirrors - three NPN and two PNP three of them from NXP
and and two from Infineon (was Siemens).
You'd need to look at the data sheets to work out which would suit you
best

View in a fixed-width font such as Courier.

BATT---------------+-----------.
. | |
. | |
. [3K9] |
. | |
. | |
. / /
. |< |<
. | |
. +---------+-----------|
. | |\ |\
. | | |
. | | |
. +-----------+ Iout
. | . [166k] . |
. | . COM---+------------------

The 10:1 asymmetry is a bit on the high side - your spare 30uA would
accomodate 5:1 - 80k and 1k4

That post is a forgery. The circuit is miswired and even when correctly
wired will never stay within +/-20% for the same variation in power supply
regardless of matching...

Sorry Fred. It isn't a forgery - I usually post via google groups, but that
isn't working at the moment so I'm use the Astraweb login that Frank
Bemelman passed on to me when he stopped needing it - but you are right
about the miswiring (which has been corrected above).

The circuit isn't stable against changes in the battery voltage, but then
again, neither is yours, though yours will suffer somewhat less because the
asymmetry in this version of the asymmetric current mirror does decrease as
the battery voltage drops.
 
B

Bill Sloman

Jan 1, 1970
0
Fred Bloggs said:
John said:
Lots of interesting stuff here thanks.
Just to clarify I have a 2 x AAA cell supply and want to drive an LED
at
150uA which will be around 2V.
The AA supply will obviously not be completely exhausted by the time
there
is insufficient voltage to light the LED but the intensity needs to be
reasonably constant until then.
By the way, why do trolls despise themselves so much as indicated by
the
intense anger?

---
Jeezus, what a fucking waste of time...

If, in your initial post, you'd have stated that all you wanted to do
was drive an LED at 150µA from a couple of AAA cells, then the answer
you'd have gotten back would have been pretty close to:

+--------+
| |
|+ [6200R]
BAT |
| [LED]
| |K
+--------+

and you'd probably have gotten back two or three posts instead of40.

LOL, who's the troll???

JF

The LED intensity will not be the same from 3v down to 2v IDIOT!


---
No shit, Sherlock?

Other than some 20 or 30% babble on the current tolerance and some
other gobbledygook about a 3V regulator and making something from 65µA
I don't see where you said it had to be and, you inconsiderate
buffoon, why didn't you just say all you wanted to do was light an
LED in the first place?

Plus, we got no answer to my :

"If you're not allowed to use integrated circuits, then why don't you
post the schematic for the 3V regulator you've come up with, as well
as with what's feeding it and what the load looks like?"

which, had you replied, would have gone a long way to clearing things
up.

I think Phil was pretty close on his assessment this time.

JF

He should make the circuit self-referential:)

You can do that with an asymmetric current mirror and one extra
(complementary) transistor
View in a fixed-width font such as Courier.

BATT---------------+-----------.
. | |
. | |
. [3k9] | .
| |
. | |
. |/ |/
. |< |<
. | |
. +---------+-----------|
. | |\ |\
. | | |
. | | |
. +-----------+ |
. | | .
\| |
. +---------+
. | |
. <| |
. /| |
. | |
. | _
. | _V_
. [91k] | .
| | . | | COM--- -----------------------+-----------+

and that is a seriously stable circuit, though the forward voltage drop
across the LED has too much tolerance for the current to be all that
well-defined.
 
J

John Devereux

Jan 1, 1970
0
Hey John,

I think this would actually work even better than it might seem at
first. The response of the eye is not particularly sensitive to
absolute brightness levels, especially when they change slowly. All a
constant current circuit would achieve is to hasten the hasten the end
of battery life - because of the increased current *and* the
inevitable voltage drop accross the regulator.
No you didn't.

You simply didn't think it through...then you tried to justify yourself -
what an IDIOT!

Why is it that top guys like Spehro, Bill S and others can provide helpful
excellent replies and in a generous non-confrontational manner and you wade
in with your beligerant nonsense?
Maybe it is because you are a deeply unhappy and bitter IDIOT who is hiding
a dark secret?

Are Beech and Raytheon aware of the sort of malicious noxious abuse you dish
out and the sort of dumb mistakes you make?
Are their shareholders aware?

Well if they weren't, they soon will be...

At least he doesn't hide behind an anonymous email address, "Dave".

Or is hothouse.com really your ISP?

<http://www.google.com/search?hl=en&safe=off&q=hothouse.com>
 
D

Dave

Jan 1, 1970
0
John Devereux said:
Hey John,

I think this would actually work even better than it might seem at
first. The response of the eye is not particularly sensitive to
absolute brightness levels, especially when they change slowly. All a
constant current circuit would achieve is to hasten the hasten the end
of battery life - because of the increased current *and* the
inevitable voltage drop accross the regulator.

Sorry, but nobody said anything about the eye or visible light, but thanks
anyway.
At least he doesn't hide behind an anonymous email address, "Dave".

Or is hothouse.com really your ISP?

No, not hiding. Just a convenient spam harvester trap which inconveniences
the owners of such sites as well.
Are you objecting to the second use John?
Dave
 
H

Hattori Hanzo

Jan 1, 1970
0
John Fields said:
Lots of interesting stuff here thanks.
Just to clarify I have a 2 x AAA cell supply and want to drive an LED at
150uA which will be around 2V.
The AA supply will obviously not be completely exhausted by the time there
is insufficient voltage to light the LED but the intensity needs to be
reasonably constant until then.
By the way, why do trolls despise themselves so much as indicated by the
intense anger?

---
Jeezus, what a fucking waste of time...

If, in your initial post, you'd have stated that all you wanted to do
was drive an LED at 150µA from a couple of AAA cells, then the answer
you'd have gotten back would have been pretty close to:

+--------+
| |
|+ [6200R]
BAT |
| [LED]
| |K
+--------+

and you'd probably have gotten back two or three posts instead of40.

LOL, who's the troll???

JF

The LED intensity will not be the same from 3v down to 2v IDIOT!

Too fucking bad, idiot!
 
H

Hattori Hanzo

Jan 1, 1970
0
No you didn't.

You simply didn't think it through...then you tried to justify yourself -
what an IDIOT!

Why is it that top guys like Spehro, Bill S and others can provide helpful
excellent replies and in a generous non-confrontational manner and you wade
in with your beligerant nonsense?
Maybe it is because you are a deeply unhappy and bitter IDIOT who is hiding
a dark secret?

Are Beech and Raytheon aware of the sort of malicious noxious abuse you dish
out and the sort of dumb mistakes you make?
Are their shareholders aware?

Well if they weren't, they soon will be...

You're a goddamned idiot.
 
H

Hattori Hanzo

Jan 1, 1970
0
This used to be up the LM10(L)'s alley, and it still is if parts
larger than S08 are tolerated - supply current is still in the 300uA
range.

Getting a low voltage low power op amp is no trouble (tlv2760 and the
like), but including a reference (~1V2) to keep things constant at low
currents isn't easy. A TLVH431 may operate at as low as 50uA, but is
not characterized to do so. A crude reference can be obtained using a
simple diode.

120uA doesn't seem like much current to keep an LED visibly lit. Have
you tried it?

RL


He is a total retard. His very first statement is ambiguous, at best.
He states "150uA which will be around 2V". I don't think this dope knows
ANY electronics to be that far off the mark.


LEDs typically top out at 150mA, not micro-amps.

This LED should probably run at 20mA.

150µA probably won't illuminate it at all.
 
L

legg

Jan 1, 1970
0
Lots of interesting stuff here thanks.
Just to clarify I have a 2 x AAA cell supply and want to drive an LED at
150uA which will be around 2V.
The AA supply will obviously not be completely exhausted by the time there
is insufficient voltage to light the LED but the intensity needs to be
reasonably constant until then.

This used to be up the LM10(L)'s alley, and it still is if parts
larger than S08 are tolerated - supply current is still in the 300uA
range.

Getting a low voltage low power op amp is no trouble (tlv2760 and the
like), but including a reference (~1V2) to keep things constant at low
currents isn't easy. A TLVH431 may operate at as low as 50uA, but is
not characterized to do so. A crude reference can be obtained using a
simple diode.

120uA doesn't seem like much current to keep an LED visibly lit. Have
you tried it?

RL
 
H

Hattori Hanzo

Jan 1, 1970
0
Jeezus, what a fucking waste of time...


I just looked through the original post and thread. This retarded
bastard did not answer a single post in that thread, which he started.

There were people asking him for more information from the very
begriming. He ignored EVERYONE. The retarded bastard deserves NOTHING.
 
D

Dave

Jan 1, 1970
0
Hattori Hanzo said:
He is a total retard. His very first statement is ambiguous, at best.
He states "150uA which will be around 2V". I don't think this dope knows
ANY electronics to be that far off the mark.


LEDs typically top out at 150mA, not micro-amps.

This LED should probably run at 20mA.

150µA probably won't illuminate it at all.


What, not IDIOT2.
Try it IDIOT2
Then you can shut up.
Dave
 
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