op-amps with AA batteries?

My off the shelf solution would be to use 2 batteries. Or with one opamp to produce a virtual ground(1/2 battery voltage), or use a small switching supply to produce -battery. and use rail to rail opamps, some of which go as low a 5volt minimum supply total.

Use some low-voltage opamps, and run them off +-1.5.

Or use a couple of 9 volt batteries, +-9 supplies.

Or build a complicated dc-dc converter to make +-15 from 1.5.

John

By using an op-amp that was designed later than ABOUT 30 YEARS AGO!!!!

Or the LM10, which is 25 years old at the very least, and works down to a supply voltage of 1.1V. Or the LM358, which has worked at supply voltages down to 3V for just as long.

Or any of the innumerable 'new' low power op-amps. National lists one that is supposed to work at 0.9V, which is end-of-life for one of your AA cells. You probably want to use at least a pair of cells so you can use a 1.8V supply amp; using four cells will open you up to a world of possibilities.

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www.wescottdesign.com

redesign the circuit to use less.

you can run some op-amps off 3V (+/- 1.5V supply) eg: LM324 or LMV844

That spam is posted through Google Groups. You are helping the spammers by posting through there, yourself. Find a real NNTP server and you won't see much spam.

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You can\'t have a sense of humor, if you have no sense!

Try LM324 single rail (down to 3V) quad opamp.

Maybe more immediately, since other places that carry newsgroups do screen out the blatant spam, a lot less shows up elsewhere. One can at this point pretty much know that someone complaining about "too much spam" is using google. Not only is google the source of much of the spam, but they display it, so it looks a lot worse at google than many real newsservers.

I seem to recall that dejanews made a point of not archiving spam, dealing with it the same way good ISPs do, but that would seem to have stopped when google took over the archive, or at least at some point since. They might not have so many search problems if they actually removed the spam before archiving the messages.

Michael

Google Groups uses have to flag it before its removed, but are either too lazy or too stupid to clean up their nest by clicking on 'Report This'.

I have started using Bing instead of Google. Google adds any possible spelling of your search terms, making it difficult or impossible to track down some rare items. the sat maps are more up to date on Bing, as well.

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You can\'t have a sense of humor, if you have no sense!

And when you leave Google, be sure to send a note to them and to at least one of their advertisers about _why_ you don't want to use Google Groups any more.

You can affect _some_ business people by an appeal to what's right; you can affect _all_ business people by an appeal to their pocketbook.

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www.wescottdesign.com

I will see about getting news elsewhere. I was on usenet in the early

90's but it's all different now. I will leave google now... Thanks for all the op-amp advice, I am getting my ideas through a Circuit "Encyclopedia" which has all +/- 15 op-amps and I am glad there're other options....

If all you want is text (no pr0n) Usenet, individual.net is only about $15/year ($10EUR/year). The customer service is second to none.

Spam spam spam . . . Spam spam spam . . .

Hey, what you want ain't a big deal.

You choose an amp that works with low voltage supply. (from national or maxim or ...)

Then you bias the sucker(s) to 1/2 Vcc instead of ground and just do what you want with the amps. In the old days they might "lock up" (go to one or another supply rail and hang). These days? Amps are much much better.

You only have to keep in mind the divided voltages your 'e dealing with (assuming some exceed Vcc - protect the input pins).

In the 70's we were pushing 701s' to 5 volts (2.5 volts plus and minus, and 747's to 4 volts).

LM324 - Ick!

That's the problem people make, they don't look at the date of the book. It gets even worse with the internet, because there usually isn't a date put on the schematics. So people who "just want to build the circuit" have real problems, not because the parts are dated, but because they don't realize it, and can't figure out why they can't find the parts.

The classic was about a decade ago when it was relatively common to see people asking about where to get tunnel diodes, they were far more common than should have been. It was clear people were stumbling on old schematics posted on the internet (who knows why someone bothered to post schematics that used tunnel diodes on the internet in general pools of schematics), presumably thought they were good to build since they didn't have many parts, and then had problems finding tunnel diodes.

Old circuits aren't in themselves bad, but one has to be aware of their age, since yes, low voltage/low current op-amps didn't arrive until a certain point, and even after they were available they weren't commonly used in hobby circuits.

Michael

So where can I get a few tunnel diodes?

:-).

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www.wescottdesign.com

In the tunnel. Watch out for the trains, though. ;-)

--
You can\'t have a sense of humor, if you have no sense!

Or else try the free servers ...

motzarella (now known as eternal-september) albasani x-privat aioe

aioe is the worst because you have a max of 25 postings per day, or something like 5 in any 10-minute period after which you get blacklisted. Not good when you subscribe to

53 fora!

Forget aioe.

You'll get blacklisted on 90% of the NNTP clients, as well. Also not good.

Okay, this is me, the OP, now I'm off of google, and everything looks better from here.