nice opamp

Neat! Thanks for the hint. Best of all it's around $0.50 in quantities. Come to think of it, the good old days are right now. If only the young lads and lasses would get off that couch, toss the Playstation into the corner and build something.

But they don't know how... nor do they care :-(

...Jim Thompson

Heck, I'd like to know how, but most the time I asked teachers, they answered: why do you care, buy a ready made module and hack around it. Basically, use blocks and connect them together...

On a sunny day (Sat, 08 Dec 2007 12:56:17 -0800) it happened John Larkin wrote in :

Looking at the diagram I'd say the output is only capacitive ;-) Seems they forgot a dot.

...and why does it come in two versions with reversed power pins, but otherwise exactly the same (unless I missed something), I wonder? So you can get the wrong one and blow them up?

Darn, it was too good to be true.

I like the saturation detector; I've gotta try one and see if it's any good. Lots of opamps wind up badly if they rail.

John

You got really bad teachers. Why, back in the good old days...

Bob

Hmm that goes for my oldest son, but my youngest son (okay, he is nearly 6) seems to be developing a real interest in technical stuff.

That does make it ceaper than the LM10, which has been around for a while now.

-- Bill Sloman, Nijmegen

One prof told us that when we are grown up transistors will bne obsolete and it's all chips. ROFL! Luckily I totally did not believe him and that fact provides me income now.

That goes to the history of sot-23 opamps. Be careful.

Best regards, Spehro Pefhany

Right. CMOS amps tended to have v+ and v- reversed. Another thing I like is that the 33503 version has the "standard" pinout.

John

"Jan Panteltje" ...

Also be prepared to use it only with GND properly connected to proper soil or rock: the input resistance is expressed in terra-ohms ;)

Apart from typo's like that it looks like a nice chip. Would have preferred Vin+ at another corner to keep the input current really at

NSC started the "wrong" pinout, IIRC, but the rest of the world didn't follow. No doubt Motorola wasn't sure and wanted to cover both bases when they introduced this IC. It's interesting how old it is; my datasheet copy in my computer is dated 4.5 years ago, and it's rev 7 (it's now at rev 10). The oldest copy at PartMiner is rev 3, dated Feb 2000, so this chip must be more than eight years old.

This opamp isn't that appealing, it's 30nV input noise is a little on the high side, for example, and so is its 1.2mA supply current. That would be too high to use in the 250V current-sense ground-output thread.

Yes, but you can build a pre-amp that is able to run on a single AA cell. Ok, most of us can also do that with transistors but young lads often can't. They need a shrink-wrapped solution in a plastic package along with a detailed app note on how to wire it up.

I'm doing a tachometer thing, and using this as the integrator for variable-reluctance speed sensors. Given a sensor on the housing of a big rotating machine, sorta near some gear teeth on a shaft, a little noise doesn't matter. This amp is ideal here, and cheap!

If the saturation detector works, I can get rid of some integrator clamp stuff, always a nuisance.

These vr pickups output voltage proportional to frequency, and one can give you millivolts to >100 volts p-p as the speed varies.

John

The MMA2260 datasheet only has labels for 7 of the 8 pins on one side (but spread out so they span all 8), which moves the power pins, and then to keep you on your toes the text version calls 'Vdd' 'The power supply ground' and 'Vss' 'The power supply input'.

2) he almost surely don't know how to design things either

It's just a matter of motivation and work. When I was 16 and we just learned about derivatives, knew almost nothing about integrals, logs and exponentials, ode,... I went to an electronics componants show in Paris and bought a few electronics books. The selection process was pretty simple: just quickly skim through some and picked up those that made me think: "Great, I understand almost nothing so I'm sure I'll learn something". I just keeped re-reading them until it made sense. 1 year and a few more books later I was OK with complex fequencies, laplace & fourier transforms,...

Just don't be shy :-)