opamp clamp

So, what are your recommendations of effective charities, the ones you prefer?

John

--
The ones I prefer are the ones I support, of course, but I don\'t
recommend charities since whom people choose to support is their
business and none of mine.

Which could be interpreted as "none."

Well, I'm just always curious about whether various people make an effort to help others, especially the miserable people who grow our food and coffee and chocolate and mine the stuff we use to make our giant SUVs and wide-screen TV sets. Too many people publicly lament the miseries of the world but do nothing personal to help.

Read this:

John

[snip]

I liked this, "Europeans prefer to believe that their tax system is their charity" ;-)

Elect Hillary and that's what you'll get, government dominance and NO charity... the conservatives won't have anything left to give, OR enough income to employ anyone either :-(

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
         America: Land of the Free, Because of the Brave

Really a good book. I read it several months ago--it's all about where the rubber actually meets the road.... Makes leftists almost as crazy as Bjorn Lomborg ;)

Of course, Pope Benedict tends to make both sides crazy, which is usually a good sign.

Cheers

Phil Hobbs

--
Of course, as could yours.

What is this, charity wars and we\'ll soon be wielding receipts to
prove who\'s "better"?

Gosh, you're in a bad mood tonight. I suspect you've either had too much to drink, or not enough.

John

I guess you can't be happy after all, John.

--
Keith

[snip]

"Not enough" is always problematic ;-)

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

| 1962 | America: Land of the Free, Because of the Brave

I use a variant on this circuit, all the time. open and closed loop. I use my favourite beast, a dual NPN/PNP transistor. One more sets my clamp voltages, Vbe above 0V, and Vbe below Vcc. cheap, fast, small. and clamps pretty damned accurately to the supply rails.

for temp compensation, use one dual BJT for the +Vbe reference and clamp, and the other dual BJT for the (Vcc-Vbe) reference and clamp. Voila, temperature tracking.

Cheers Terry

--
Suspect away, your conjecture means nothing.

-----+---------+--- +5 e -----, | e pnp b -- | -------- |---+-- b c | Ra | c ,--------+ | ,-----+ '-----+ | c | | c | | npn b -- |----+-- b Rb | e -----+ e | | _________ | | gnd | | | | gnd +--| network |--+ | |_________| | | | +---/\\/\\----, | | __ | | ---/\\/\\--+--|- \\ | | | >----+---+----- gnd ---|+_/

The matching aspect is nice, except of course, it's not easily adjustable.

The "network" required for stability compensation is an issue nicely missing from the first configuration.

yup. Except I cheat, and only use one base resistor (saving up to be scottish...)

I first whipped it up a few years ago, when I had a problem with an analogue mux that didnt like BAV99 supply rail clamps and a 1k series R. I didnt want to use a schottky equivalent, because it was a whole new component, and there would only have been 1 of them on the whole board....

I use it all the time now :)

left as an exercise for the reader....

:)

Cheers Terry

I was thinking of making the clamp rails like...

+5--------------+ | R | | +-- C +--B E | +--------- VCH | | R | | +---------- VCL | +-- C +--B E | | R | | gnd

As far as compensation goes, the clamped opamp does want to oscillate, but a bit of capacitance from opamp output to the inv input fixes that, ie, "network" is one small cap.

But there's a gotcha: the b-c junction of the lower opamp clamp transistor will be forward biased...

which messes up the opamp big-time. I can use this circuit in my integrator, which works against +2.5 volts, but not in my front-end stage, which, like this figure, works against ground.

John

I pay taxes and get a reasonable return, in security, business environment, legal protections, and public works. I could move to Nigeria or to Sweden if I wanted, but I'm doing fine here.

And G W Bush doesn't set the tax rates, or pass the enforcement laws; Congress does. What W did was push and sign a tax rate CUT.

John

Not enough is easier to cure than too much.

Ron Paul.

Cheers! Rich

I think he has the same kind of happiness as a contented cow has.

Cheers! Rich