How do ADCs tackle negative value analog input ?

Only because you cannot read. ...or understand.

Another Fields' lie. BTW, how's your twin, DimBulb?

Level shifter? The whole concept is a hack, here. Where is "zero", moron?

Another Fields' lie. Keep going...

That wasn't the question asked. But you don't care. You're only here to prove how "smart" you are. Really, all you do is show what a hack you are by publishing your Fields brand of hairballs. What a loser.

Actually, I did. Because you can't read, it's no surprise you don't get it.

Yes. The truth is not an ad hominem. It's the truth. Sorry if it hurts your sensitive ego.

Of course you would. It's obvious that you're not an engineer.

Question answered.

Simple. Because you can't read.

Obviously you don't understand the article. It *is* trivial. A little hierarchy and it's a coupe of minutes work.

On Sat, 12 Jan 2013 21:00:54 -0500, snipped-for-privacy@attt.bizz wrote:

--- Ah, now I see that your problem is one of marginal reading comprehension; let's see if we can, once again, clear the situation up for you, OK?

Referring back to the OP's post, one would think that since he referred to a bipolar input signal going into an ADC and inferred that all zeros out of the ADC corresponded to zero volts in, his question was, basically, "How do I match the two up so when the input goes negative I get something which makes sense out of he ADC?"

The obvious choice - since it can be used with any ADC - is, of course, a level shifter, with its output at zero volts when the input signal is at its most negative point. In the OP's case, -2.5V.

---

--- The implementation of a "250ish 2in mux" solution is less trivial than the implementation of a dual opamp solution?

As I mentioned earlier, there is a solution simpler than mine, suggested by others here:

Version 4 SHEET 1 880 680 WIRE -176 16 -208 16 WIRE -144 16 -176 16 WIRE -32 16 -64 16 WIRE 112 16 -32 16 WIRE 224 32 176 32 WIRE 256 32 224 32 WIRE -32 48 -32 16 WIRE 112 48 80 48 WIRE 80 128 80 48 WIRE 112 128 80 128 WIRE 224 128 224 32 WIRE 224 128 192 128 WIRE -368 144 -368 112 WIRE -272 144 -272 112 WIRE -176 144 -176 16 WIRE -32 160 -32 128 WIRE 80 160 80 128 WIRE -368 272 -368 224 WIRE -272 272 -272 224 WIRE -272 272 -368 272 WIRE -176 272 -176 224 WIRE -176 272 -272 272 WIRE 80 272 80 240 WIRE 80 272 -176 272 WIRE -368 320 -368 272 FLAG 144 64 +10 FLAG 144 0 -10 FLAG -368 320 0 FLAG -368 112 +10 FLAG -272 112 -10 FLAG -208 16 ACIN FLAG -32 160 +10 SYMBOL voltage -176 128 R0 WINDOW 3 24 96 Invisible 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value SINE(0 2.5 1000) SYMATTR InstName V3 SYMBOL voltage -368 128 R0 WINDOW 3 16 102 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value 10 SYMATTR InstName V1 SYMBOL res -16 144 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R1 SYMATTR Value 100.0k SYMBOL voltage -272 128 R0 WINDOW 3 16 102 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value -10 SYMATTR InstName V2 SYMBOL res -160 32 R270 WINDOW 0 32 56 VTop 2 WINDOW 3 0 56 VBottom 2 SYMATTR InstName R2 SYMATTR Value 24.9k SYMBOL Opamps\\LT1001 144 96 M180 SYMATTR InstName U1 SYMBOL res 208 112 R90 WINDOW 0 68 54 VBottom 2 WINDOW 3 69 52 VTop 2 SYMATTR InstName R3 SYMATTR Value 2.49k SYMBOL res 96 256 R180 WINDOW 0 36 76 Left 2 WINDOW 3 36 40 Left 2 SYMATTR InstName R4 SYMATTR Value 10.0k TEXT -360 296 Left 2 !.tran .01

Single opamp, four resistors, nice high impedance for the AC source, nice low impedance to the ADC input...

Hard to beat, even by "250ish 2 in muxes", huh?

-- JF

if 0V is of special signifigance you may need an input of 0V or use a bipolar ADC.

bit

wire

would

exercise.

Keith, if you were much of a human you would be ashamed to have posted nearly pure ad hominems. Have fun with the strawman.

?-)

exercise.