Digital, or analog?

By definition, it implys that it is continous. Linear, no, but continuous is essential.

Discrete, yes, again by definition.

I don't believe that necessarily most are binary nor sampled.

From this perspective, if you want to make up your own definitions, and so does everyone else, what point is there to discussing *anything*?

You are denying that the standardized definitions are correct, and that is an absurd stance to take, which makes *nothing* you say worth discussing.

I disagree. Many standardized definitions are committee compromises, and have sometimes what comes out of a committee has little to do with what real people try to mean or understand when using those words (especially if a committee has gotten politicized or influenced by marketing agendas).

(in general. not expressing an opinion on digital/analog). IMHO. YMMV.

OK let's not tooooo far to the extreme .

So a relay is "analogue" in sense that on closure its resistance may change "gradually" from 10^10 ohms thru 10^8 ohms to 10^-3 ohms.

And I've worked with "analog" systems capable of noticing individual electrons as they came. Had an interesting argument with bull-headed chemistry post doc that some of his instrumentation requirements were silly as they implied capability of measuring tenths of electrons per second -- can anyone say "gain bandwidth product". I "lost" as I was ONLY a technician he was a *PHD*

I've seen a 7400 series inverter used as an 'op amp' Don't recall why it was done, suspect was just to prove it could be ;/

I was not referencing just *any* definitions. I say *those* definitions. They are not in dispute by any reputable source.

You stake *your* reputation against the entire industry when you deny they are correct, and that is simply absurd!

So we are going to ignore indisputably good standardized definitions that the industry (not to mention the Federal government) uses, and you think that is going to in any way assist in discussing this topic???

Of course to make it work as an analog circuit... components had to be added. Which means that was *not* the same "circuit" which functions as a digital circuit, even if it used the same IC.

Circuits may or may not be analog or digital, though *clearly* some are one or the other. Signals *are* one or the other, by definition.

This is a general prerequisite for any kind of communication, digital or analog ;-)

That is demonstrably incorrect. All circuits that have a physical instantiation are analog, as are the signals that they process.

In and of itself, a digital state has no representation in the physical world. To instantiate or process a digital state, it must be encoded into a voltage/current analog. People have been known to group binary states into a multi-state logic and represent the combined states with a single value of voltage/current analog. If you group enough binary states together the analog of the digital value becomes indistinguishable from continuous.

COMPONENTS ;? :?

Yes, exactly! The two resistors are only a slight addition, but of course they dramatically change the way the circuit works!

Ron and I have both worked in standards bodies helping to write standards, so we have a little different perspective on this.

A standard is typically intended only to reduce confusion in the context for which it is intended.

e.g., the form factor for electrical wall outlets and plugs are "standardized" around the world, but they're different standards. You can go to Europe (or any of a host of places) around the world and argue until you're blue in the face that "the standard" electrical plug looks like the US version, and you can produce the drawings and definitions to prove it, but you'll still not be able to plug in into an outlet in the UK or Germany or Japan or China or Russia or a host of other places. You'll be right in the context of the US, but it won't help you run your shaver over there.

You insist on using a single definition that you pulled out of a "standard" somewhere. It's causing you trouble and you don't seem to be able to recognize that outside of the context for which that standard was developed it's no longer "the" definition, just "a" definition. Anyone else's definition is as arguably good here as the one's you've cited, hence the current discussion.

Eric Jacobsen Minister of Algorithms, Intel Corp. My opinions may not be Intel's opinions.

Well, not as long as YOU get to pick which sources are to be considered "reputable" and which aren't...

Bob M.

Let's try another simple example, shall we?

Last year, the organizers of a charity drive came to their local electronics-tinkerer type, and told him that they wanted to put a big display up that would show how well they were doing toward meeting their year's goal.

"No problem," he says. "I can rig up a big meter movement to this here variable resistor, we'll put it on a billboard, and I'll label various points on the meter as '10%,' '20%,' and so on. Each day, you send someone to the billboard, and they can turn this knob to set the pointer to wherever it needs to be that day!"

"Perfect!" they replied, and the new charity-drive billboard went up. Worked like a charm, too. Each day, the designated knob-twister would adjust the position of the pointer, and everyone was happy with the result. Until THIS year's drive, when they found that the big potentiometer that the tinkerer had originally used burned out, and no replacement was available.

"Still no problem," he says. "I'll just replace it with a string of twenty or thirty discrete resistors, and you can then move the pointer by choosing where in that string you attach this alligator clip. It'll work just like before!" And sure enough, it did.

The question at this point should be clear. The position of the pointer on this big charity-drive billboard is being controlled by the current coming up to the meter movement in both cases - and also, quite clearly, when the thing was first put up that this current can be considered to be an analog representation of how close this group is to their goal. After the modification was made, though, the thing still works in exactly the same manner - the information is being delivered to the billboard via a current whose amplitude is "analogous to" that information. It just is no longer capable of being

Are you arguing that we now have a "digital" signal going over that wire? And are you going to actually think about your answer, or are you going to defer all thought to some "standard"?

Bob M.

Well, it all depends on which definition of "analog" you're using I guess. From the following comment:

...I would have assumed that we were in agreement there. In which case "analog" and "digital" BOTH refer to how information is encoded onto a signal, but not really the signal itself. Elsewhere I have given an example of a signal which cannot be unambiguously classified as either "analog" or "digital" in the common (and sloppy) use of those terms merely by looking at it. Given that confusion, I am simply proposing that if you really want to see what's going on, you think of circuits and signals as simply being "electrical" - and leave the words "analog" and "digital" for use only in pointing to encodings.

Admittedly, most of us in the industry are VERY used to using these terms another way (and I do so myself in many cases), and it takes a real effort to change that perspective. But it is very often valuable to do so. Far too often, I have seen various claims of advantages or disadvantages in a given system presented as being the result of something "being analog" or "being digital," when in fact these concerns had nothing to do with what was being considered.

Bob M.

Right. But my point was that the model has to be chosen depending on the question. We can still model a relay as digital because the elevators don't usually show any measurable difference in behavior due to these analog realities. And we can model a relay as analog if we are looking at, say, the effects of humidity & back-EMF on the life of contact plating.

IMHO. YMMV.

Oop, sorry, Ron, if that's not true. I was mistaken over who's post was included here.

Eric Jacobsen Minister of Algorithms, Intel Corp. My opinions may not be Intel's opinions.

I guess. As long as you don't measure it while the contacts are arcing :-)

The faster the digital circuit goes the more analog it becomes.

If you try to sit on me, I can squeeze through places you can't follow.

Jerry

Lousy choice. The symmetric CD40xx, on the other hand, was well enough suited to be used in at least onecommercial product.

jerry