op amp buffer and transistor buffer

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Hmmm, I reread the thread... It's now clear. I thought the point was to build some current source, where I got mixed with another thread... Well, maybe.

So, the purpose is to allow swings at least right down to gnd and slightly below with a single supply circuit...

The second circuit is the right one. Clever!

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Ok, I reread the thread as this didn't make sense to me. Bummer, I thought it was to build a current source!

Now that I understand it's for allowing output swing down to, or slightly bellow gnd, with a single supplied opamp.

The right circuit is the second one. Clever!

Thanks.

What water? [On the Road, in Lubbock TX]

;-)

and

put,

alue

can

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Nice..

Several towns on Long Island got a warning to boil water last week due to Escherichia C. It was only found in 1 sample, and the warning was lifted after a couple of days.

"Tom Del Rosso" wrote in news:j12dvc$bao$ snipped-for-privacy@dont-email.me:

Worst drought here since the 1920s. A bit of a sprinkling late today, but not really enough to make a difference to the farmers (eg. cotton). Even E. Coli contaminated water might be an improvement.

Best regards, Spehro Pefhany

output,

value

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I tried a minimal photodiode amplifier once.

This works except at zero photocurrent, where you get weird spikes appearing due to loss of negative feedback at 0V.

I think that this circuit should fix it.

Another configuration might be to use the opto as a -0.5V supply rail for the opamp.

One of my best buddies at MIT was from Lubbock, Bufford Carl Terrell, he went by "Tex" ;-)

He was a Physics major, failed out and became a circuit (*) preacher in West Texas :-)

(*) That means traveling for you geeks :-)

He's surely retired by now, but last I heard he was a law professor at Rice :-) ...Jim Thompson