At what point does your circuit become "digital"? - Page 1
Forum section: electronics / beginners

author: Beamin
author_rank: Super Contributor
timestamp: September 30, 2017, 12:38:43 am
content: Vague question but as I learn more I'm wondering when I have crossed this boundary. If you are using an Arduino that's digital with analog passives. But what about a 555 timer circuit? Still analog because you could take the design of the chip duplicate its circuit and make it into all basic analog parts? What about a counter with a 555 and a 4017 counter? Is that digital or hybrid device? IF you are doing electronics and all you care about is getting a result like meeting a design specification and have to option of making an analog circuit or a digital one isn't it simpler to just make digital circuits and only make analog devices when you have to? Is a switch mode power supply or a class D audio amp considered digital hardware?Does the definition lie when you are using gates? What about op amps they act like gates don't they? I hvent been doing this hobby for a few years and I have forgot a lot that just use to come to me instantly.

author: ataradov
author_rank: Super Contributor
timestamp: September 30, 2017, 01:45:14 am
content: The easy answer - when you can ignore analog nature of the device.Even with pure MCU projects with "digital" pins, there is still plenty of "analog" stuff to worry about for high-speed interfaces.Try to use DDR SDRAM and not do proper impedance matching, and you will quickly learn just how much analog there is in digital stuff.

author: vk6zgo
author_rank: Super Contributor
timestamp: September 30, 2017, 02:48:36 am
content: Quote from: Beamin on September 30, 2017, 12:38:43 amBack in the day, many digital functions were performed using discrete components."Flip- Flops" were made using twin triode vacuum tubes, & , if you wished you could duplicate the operation of your 555 with discretes.Even if 4017 counts to 10, rather than 2 or some whole number power of 2, it still is a "digital" device.In a "pretend" world, digital devices would only be concerned with "ones & zeroes" , but in the real one, gates are really just "bastardised amplifiers", so things like linearity can, & do, affect your signal integrity.Frequency domain stuff like stray capacitance etc, transmission line effects, & so on, all affect both digital& analog circuitry.In a practical sense, if you have some analog circuitry feeding an ADC, that device would be where the transition is made, but that raises the question of whether an ADC is purely a digital device.It has an analog input which has to exhibit satisfactory frequency response, linearity, dynamic range, & so on.

author: Brumby
author_rank: Unknown
timestamp: September 30, 2017, 02:50:49 am
content: Quote from: ataradov on September 30, 2017, 01:45:14 amThis is pretty much the best way to answer the question - but you have to remember that "digital" is just a special case of the analogue world in which we actually inhabit.

author: Tomorokoshi
author_rank: Super Contributor
timestamp: September 30, 2017, 04:40:16 am
content: Digital: You can analyze the circuit using Karnaugh Maps.Analog: Everything else.

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: September 30, 2017, 06:00:22 am
content: If signals only have to fall within a specific voltage or current range to have a given significance, then it's digital.

author: KL27x
author_rank: Super Contributor
timestamp: September 30, 2017, 06:59:54 am
content: IMO, digital means two states. On/off. Hi/lo. 1/0. Or to be more general, something that is digital only occurs is quantum, discrete steps. Analog means 0-X and everything between. Everything can be theoretically replicated in discrete components, including microcontrollers. You would have to slow the clock down because of inductance and capacitance. This has nothing to do with analog vs digital, IMO.I wouldn't call 555 chip analog. It has digital outputs and inputs on it. Analog describes signals moreso than circuitry.* Even an opamp... is it analog or digital? If you make it into an amplifier, you can call it analog. If you make it into a comparator, it is digital?*Even better, it describes the signal processing. If you take a curvy signal and only interpret it at a single cutoff point and call it hi or lo, then you have 1 bit digital signal. Take 3 cutoff points, and you have a 2 bit digital signal. If you simply amplify or buffer or invert whatever came in, then that is analog. But notice you can't assign an analog signal a number. You can only compare it to something else. As soon as you label it with a discrete number that doesn't extend to infinity decimal places, you have converted it into digital. You have chopped it into quantum steps. You have discarded the infinite amount of steps between this number and the next higher/lower. That's what an ADC does.

author: Brumby
author_rank: Unknown
timestamp: September 30, 2017, 09:50:45 am
content: Quote from: KL27x on September 30, 2017, 06:59:54 amThat is a bit limiting. Binary is just one of a number of possible implementations of a digital system.QuoteThat's better.QuoteCan't agree. The "inputs" could hardly be called digital. The flip-flop output I could give you.QuoteThese are better questions - ones that show digital is just a special case of analogue.QuoteA good progression in the argument - but, even so, all the stages within even the most complex ADC, MCU, FPGA or whatever, still have to follow analogue rules of electron flow.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: September 30, 2017, 11:58:50 am
content: No circuit is digital. Digital is a abstract conceptual thing used to design systems with.It just so happens that we can make a lot of real-life things behave very similar like these conceptual building blocks. The most basic example of this must be a PMOS on top of an NMOS with their gates tied to together - the inverter.However, building digital-like circuits is not limited to electronics: Mechanical logic can also be made (in fact the first computer can be argued to be mechanical, if you look at the machines thought up by Charles Babbage. Designing these blocks is then a matter of optimizing the behavior to be digital-like enough for our application - every gate has leakage, noise sensitivity, delay, rise-time and fall-time. (granted, this is often part of digital design too, but even then we tend to use very "digital" models with loading and unit-size inverters).In truth, where you draw this line is very subjective I think. To a analog design engineer, things like latches and SRAM are "digital". However, a processor architecture designer might think of the design of SRAM as very "analog"-like design, since you are dealing with differential pairs and gain etc.You could perhaps also consider how the design is done: what techniques are used? Digital design will often use simplified delay-based models, since they can ignore a lot of effects like noise, cross-coupling, risetime (they simplify risetime and bandwidth to propagation delay). Analog design usually uses SPICE or even lower level RF simulation tools.

author: tggzzz
author_rank: Super Contributor
timestamp: September 30, 2017, 12:02:35 pm
content: Analogue signals conveyenergyfrom the transmitter/source to the receiver/destination.Digital signals conveyinformationfrom the transmitter/source to the receiver/destination.Consider an RS232 (or whatever) link connecting one computer to another. The digital signal might be "hello world" converted to a sequence of 0s and 1s. The analogue signal is the voltages and currents in the wires.Consider storing programs on a domestic tape recorder (yes, it used to happen). Again the digital signal might be "hello world" converted to a sequence of 0s and 1s. The analogue signal is the two different frequencies stored on the taps.Consider a dial-up modem or many modern comms systems. Again the digital signal might be "hello world" converted to a sequence of 0s and 1s. The analogue signal is the phases and amplitudes on the wire.To corrupt a digital signal, change the 0s and 1s.To corrupt an analogue signal, corrupt the amplitudes, frequencies, phases, as appropriate.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: September 30, 2017, 12:06:53 pm
content: Quote from: tggzzz on September 30, 2017, 12:02:35 pmWhat about digital data stored in QAM signals? What about the relationship between SNR and the amount of information that can be transported along the channel? I feel like this is a very poor distinction. A very substantial part of analog design is precisely conveying digital data - not energy (the energy is just needed in order to do so). The main reason of an RF link is to convey information, and not energy. I would hardly call that digital though: You can convey analog information such as speech without at any point using digital "gates".

author: tggzzz
author_rank: Super Contributor
timestamp: September 30, 2017, 01:31:27 pm
content: Quote from: TheUnnamedNewbie on September 30, 2017, 12:06:53 pmAs I wrote, and you snipped, "Consider a dial-up modem or many modern comms systems. Again the digital signal might be "hello world" converted to a sequence of 0s and 1s. The analogue signal is the phases and amplitudes on the wire."Digits are not "stored" in QAM/(C)OFDM/GMSK/FM/etc signals. See below w.r.t. interpreting energy.QuoteSee Claude Shannon's seminal paper which completely defines that. Seeanycommunications theory textbook; theyallrefer to it and examine its implications in depth.The effectiveness of digital communications systems are often defined by how close a single transmission approaches the Shannon limit. For a cellular system, also consider the capacity defined by bits/s/Hz/m2.QuoteNope; that's because you don't understand comms theory. Think about it.QuoteIrrelevant. Energyisconveyed. If youchoosetointerpretthe energy (and changes in the energy) as representing digital signals, that's no different to choosing to interpret the energy as sound.QuoteTrue, but the non-trivial parts of that statement completely misses the point.In practice there are two points at which analogue signals become digital: photon counting (astronomy, optical TDR), and femtoamp currents.

author: vk6zgo
author_rank: Super Contributor
timestamp: September 30, 2017, 03:10:37 pm
content: Quote from: tggzzz on September 30, 2017, 12:02:35 pmThis is a fair enough distinction if you are looking at a digital system, but it gets a bit blurry in a purely analogue system, where the term "analogue" signal can mean several things.(1) In a simple example, the original signal could be that appearing at the microphone output caused by a person saying "Hello world".(2) That signal after amplification &, perhaps, frequency response reshaping, or whatever.(3)A signal modulated by (2).All these things carry the original spoken information "Hello world" in some form, with some characteristic which varies in proportion to the original spoken words.Not a digital signal to be seen, but information is conveyed from the acoustic input to the microphone, & ultimately to an audio transducer of some kind.

author: tggzzz
author_rank: Super Contributor
timestamp: September 30, 2017, 04:22:42 pm
content: Quote from: vk6zgo on September 30, 2017, 03:10:37 pmAgreed.OTOH, I didn't say that analogue systems don't carry information! I deliberately omitted that possibility to force people to consider theessentialdifferences without getting confused byagrey area.As far as I concerned there are only two types offundamentallydigital electronics: photon counting and femtoamp circuits. Everything else is a matter of interpretationI've never done femtoamp electronics, but if I could have found a source of cryogenic temperatures usable in a trench by the side of a road, I would have done photon counting back in 1980.

author: bson
author_rank: Unknown
timestamp: September 30, 2017, 10:10:32 pm
content: It's a bit like asking at what point do lines on a sheet of paper become letters. Letters are to words what digits are to numbers. Digital = numeric. A binary digit can be represented by a single logic level, and in general if there's two or more bits it's digital, while a single bit is merely a logic signal. For digits other than binary obviously more than two voltages or currents is needed. Our use of binary voltage levels is purely a convenient convention; other schemes have been used, and it's not hard for example to envision the receiver maintaining a voltage and the transmitter sending by switching a load (which the receiver detects as a current)... I mention this because it's a trap to think of binary logic as something not analog - it's very much analog and not treating it as such is going to result in suboptimal performance and reliability. There is no point where analog physical reality can be ignored.

author: Beamin
author_rank: Super Contributor
timestamp: September 30, 2017, 11:08:19 pm
content: How about asking this way: You run a company and like most managers you have no idea what you are talking about or how your products work. You have two departments an analoge department and a digital department with analog engineers and digital engineers. In order to make the company work efficiently you must assign things to the right department. How do you know what to assign to each department? IE you need to make an Arduino clone you would send it to the digital dept. If you needed a replica transistor radio it goes to the analog dept. If the president of the company who is not an EE asks you what type of projects go to which group, what do you tell him without going into a philosophical explanation?

author: tggzzz
author_rank: Super Contributor
timestamp: September 30, 2017, 11:37:30 pm
content: Quote from: Beamin on September 30, 2017, 11:08:19 pmThe only sensible response would be to resign from such an idiotic dysfunctional company. To all intents and purposes, I have done that! (Cryptically, that specific company was in Browns Lane in the S of England, and was infamously run by accountants).At an interview once, the HR-droid listened to my background and experience, and then asked "now, are you really a hardware or software engineer?". It was instantly obvious that such "listening" was a euphemism - I made my excuses and left - and got a job at a decent company (HPLabs).The fundamental principal is that attempts to pigeon-hole people leads to sub-optimum solutions - famously expressed as "organisations are constrained to produce products that mirror their organisational structure".

author: KL27x
author_rank: Super Contributor
timestamp: October 01, 2017, 01:01:34 am
content: QuoteWell, the timing cap input is something you can call analog. (OTOH, you could call the voltage level analogue, but the processing of it you might consider as digital, because the response to this input is only 1 of 2 outcomes like a comparator. A comparator is essentially a 1 bit ADC.) But if you set it up as a monostable multiivibrator, for instance, the trigger input can hardly be described as analog.I suppose you would call the timing circuit on the 555 analog. It's based on filling a cap. Compared to a delay done by say microcontroller, which is counting edges coming out of a clock (which could be an LC circuit, too, so there's a subtle difference, I suppose.)

author: innkeeper
author_rank: Unknown
timestamp: October 01, 2017, 01:39:34 am
content: Zen of Digital:Digital exists as long as you think of it in terms of 1 and 0.The closer you look at something you consider digital, the more analog it becomes.Digital is just a frame of mind, the reality is that everything is analog.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 01, 2017, 06:14:46 am
content: Digital is a subset of analog.Digital logic follows three rules:1. Gates exist. That is, logic elements with well-defined input and output states.2. The gates operate with a Boolean algebra, utilizing a certain number of signal states.3. Specified min/max propagation delays. (Propagation is a delay between an input state change and a corresponding output state change.)Anywhere these characteristics arise in an analog circuit, it can be considered digital as well.Conversely, it often happens that a circuit, intended to be digital, violates these rules. If the interconnects between gates are not simple propagation delays, but say they exhibit ringing: now the input to the next gate does not match the output from the proceeding gate. This is why so much effort is spent on maintaining good signal quality.Explanation:(1) is necessary, to show that the circuit is not reciprocal. That is, a signal applied to one port does not necessarily come out another port. A passive filter network is reciprocal, i.e., it exhibits the same gain in either direction. An amplifier is usually non-reciprocal (but not necessarily digital). Digital must be non-reciprocal, in order for sequential logic to be implemented. (It's noteworthy that, as an algebra, Boolean algebra needn't be non-reciprocal: indeed, that's one of the special powers of the equals operator. But it's rather difficult to implement and design circuits that are reciprocal. This is an important theoretical aspect of quantum computing, by the way: irreversible logic operations are equivalent to lost information and increased entropy. Quantum computers can only achieve their power by harnessing this behavior!)(2) allows for more than strict 0/1 Boolean algebra. IEEE 1164 is an example of such a system. In short, the system is extended to allow for outputs driving outputs, as long as they do so in a well-behaved manner. This allows complex bus systems to be built with ease, while allowing the compiler to detect conflicts.(3) is simply reality: the speed of light is finite, and no physical logic can be truly instantaneous. In analog systems, the lesson again is well learned: there is delay everywhere, and its low-frequency approximations, inductance and capacitance.Tim

author: Beamin
author_rank: Super Contributor
timestamp: October 01, 2017, 06:35:18 pm
content: Quote from: innkeeper on October 01, 2017, 01:39:34 amBut really since we all live in the matrix our analog systems are just computer simulation which are digital. Or we could be a boltzman brain.

author: tggzzz
author_rank: Super Contributor
timestamp: October 01, 2017, 07:04:18 pm
content: Quote from: T3sl4co1l on October 01, 2017, 06:14:46 amThus spake an analogue circuit designer!I agree that digitalelectronic circuitscan be considered a subset of analogueelectronic circuits. But in the wider context, digitalsystemsas embodied in hardware and software, are not a subset. Information theory is an important extra dimension, e.g. the concepts of entropy, error detection and correction, and state spaces don't have an analogue equivalent.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 02, 2017, 03:29:10 am
content: Well, at the absolute lowest level, you have quantum information theory, where interactions can be tracked in a graph structure. Each node being a discrete state of any given particle, and each edge being an interaction causing a state transition.Physicists are more than happy to integrate over a few quadrillion state transitions, taking the sum as if they were a continuum, at which point everything is analog again (statistical mechanics, the averaged properties of large populations of particles). This includes most semiconductors (which are still quantum systems, but we owe their average characteristics to the statistics).Meanwhile, if you're working entirely in QM (QIT is more of an adjunct to it, as Feynman diagrams are to QED, to write down which particle interactions to sum over), you have the "digital" property of wave quantization*, and the analog property of waves themselves (continuous amplitude, position and time).*I put this in quotes because energy levels are discrete, but not usually Boolean. Systems that exhibit useful qubits can be considered digital without quotes.Tim

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 02, 2017, 03:39:16 am
content: Oh, sick!So at a glance, this seems right:Quote from: tggzzz on October 01, 2017, 07:04:18 pmI was just contemplating these and considering counterpoints. Offhand, entropy and state space are perfectly comfortable in the analog domain -- statistical mechanics seems an adequate, very low level example of the former, while state space control theory is perfectly comfortable with real-valued (or complex, I suppose) variables in the state vector (hey, it's just an array of differential equations, nothing digital needed).But offhand, I didn't know of any examples of the emphasized case.First hit on Google. The headline and abstract seem to be on the money. I will read this with great interest.http://preserve.lehigh.edu/cgi/viewcontent.cgi?article=2035&context=etdThanks for inspiring this ideaTim

author: EEVblog
author_rank: Unknown
timestamp: October 02, 2017, 04:11:21 am
content: Quote from: Beamin on September 30, 2017, 12:38:43 amIf you are talking in terms of not being able to duplicate with passive components, then you could argue that CMOS basically invented the "digital" era, because CMOS chips only use MOSFET transistors acting as on/off switches, nothing else, no resistors or anything else.e.g. a CMOS NAND gate:A TTL NAND gate on the other hand uses resistors:

author: EEVblog
author_rank: Unknown
timestamp: October 02, 2017, 04:15:11 am
content: Quote from: innkeeper on October 01, 2017, 01:39:34 amThe exact same thing can be said of analog.Nothing is really "analog electronics", it's just a frame of mind, if you go deep enough then it's all really quantum physics.Beyond that, it's turtles all the way down.The art of engineering is often (or at a fundamental level) abstracting to a higher layer to get the job done.

author: tggzzz
author_rank: Super Contributor
timestamp: October 02, 2017, 07:45:50 am
content: Quote from: EEVblog on October 02, 2017, 04:15:11 amVery true.I'm continually horrified at how many people only comprehend one or two layers of abstraction, and are fundamentally ignorant of other layers. That's even true when remaining entirely within software systems, let alone considering how they map onto hardware and/or could be implemented in hardware.

author: Brumby
author_rank: Unknown
timestamp: October 02, 2017, 08:00:27 am
content: .... like TCP/IP?

author: tggzzz
author_rank: Super Contributor
timestamp: October 02, 2017, 08:14:08 am
content: Quote from: T3sl4co1l on October 02, 2017, 03:39:16 amGoodQuoteMumble mumble gripe groan ... drat, I have to agree. (In theory rather than in practice, though)I suppose one could also, with a stretch of the imagination and terminology, consider analogue spread spread spectrum systems (e.g. FM) as a form of error-correction without error-detection. No, I don't want to (attempt to) justify that.QuoteThat's a new one for me!Skipping to P90, and then speed reading without too much comprehension, they note:"... Hamming distance, a key metric in digital codes .... to the adoption of related concepts such as maximum distance separability, Hamming distance is not nearly as indicative in the analog domain as in the digital domain.", P91"... We provide a geometric method to illustrate how and why, and point to nonlinear codes as the solution for analog error control.", P91"... As linear analog codes do not perform well on AWGN channels, we further study nonlinear analog codes.", P159"... We cleverly exploit the butterfly effect of chaotic systems and the successful concatenation idea from digital turbo codes, and propose two new classes of chaotic analog codes: chaotic analog turbo codes and mirrored baker’s map codes.", P160I'm undecided as to whether that means they have fuzzy digital state spaces (boring), or they have found a practicalbenefitfrom using for chaotic systems (interesting), or both.

author: tggzzz
author_rank: Super Contributor
timestamp: October 02, 2017, 08:20:21 am
content: Quote from: Brumby on October 02, 2017, 08:00:27 amThat's merely one small instance of it.By "it" I mean the context you omitted when you pressed "reply" rather than "quote"; this forum isn't edaboard nor stackexchangeThe context was "I'm continually horrified at how many people only comprehend one or two layers of abstraction, and are fundamentally ignorant of other layers. That's even true when remaining entirely within software systems, let alone considering how they map onto hardware and/or could be implemented in hardware."Start by considering an application using web services (especially SOAP and its allies). Then count how many abstraction layers there are between the application and voltages on networking cables. For entertainment, count how many times an asynchronous protocol is layered on a synchronous protocol or vice versa.

author: Beamin
author_rank: Super Contributor
timestamp: October 10, 2017, 12:46:20 am
content: Quote from: EEVblog on October 02, 2017, 04:15:11 amI was just thinking about that right before I read this thread:"What holds up the earth?"- It sits on the back of a giant tortoise." And that sits on what?"- Another tortoise: Its tortoise all the way down.Isn't that from a roger penrose book or paul davies book?Every thing is digital because you get down to plank length and plank time and teleporting of electrons. Did you know there are only 10^120 plank volumes in the observable universe and it is only filled with 10^80 particles? I think for the multiverse it would be ghrams number big. Or even just our unobservable size taking into alan guth theory where it 10^47 times bigger we might measure it in a 2 or 3 grams numbers in size.Dave: Stop reading my thoughts before you post. Click the preview button and see if you are quantum entangling our thoughts together before you post at sub luminal speeds or at least collapse the probability function BEFORE posting.

author: Harb
author_rank: Regular Contributor
timestamp: October 10, 2017, 01:05:59 am
content: All the lights in my house are Digital, bar one in the living room, which is analogue.

author: buck converter
author_rank: Regular Contributor
timestamp: October 10, 2017, 01:49:59 am
content: When I build a circuit with logic gates, and explain it to people with less knowledge, in person, I call it analog, because had I said digital, people would think that it involved software.

author: adras
author_rank: Regular Contributor
timestamp: October 10, 2017, 08:18:58 am
content: Well, I don't know much about electronics, but as a software developer I've got something in mind.I'd consider digital circuits those which are solely based on binary logic. If something is one, another thing is zero. In analog circuits however there is not just 1 or 0, there's a whole range of values. Imagine charging up a capacitor, it's not either full or empty. It can be half full, or half empty which is important to consider. Or look at an oscilloscope, if you can measure a "clean" square wave I'd say it's digital, every other wave is analog.

author: tggzzz
author_rank: Super Contributor
timestamp: October 10, 2017, 09:27:22 am
content: Quote from: adras on October 10, 2017, 08:18:58 amThat is pretty good, but would be better if you said "...consider digitalsignalsthose...".The problem is that digital logic gates are merely analogue circuits designed to spend most of the time saturated against Vcc or Gnd. It is usually possible to bias them so they operate in the linear region.Consider also flip-flops, which most people think of as being in a 0 or 1 state. But when clocking and switching therewillbe a small window where the flip flop is deciding "which way to go". Hit that window and the flip-flop will enter a metastable state for an indefinite time. Some circuitsrelyon metastability, and the higher the proportion of time spent in the metastable state, the better the circuit is performing! (Software equivalent of metastability: a distributed two-phase ACID transaction failing).Consider also logic simulators, in which each signal can, often, be assigned 9 different values.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 10, 2017, 04:45:45 pm
content: Yeah, the field is more general than binary: it'sdigital. Binary is just the most convenient realization of digital electronics, while being fairly efficient: a consequence of 2 being close to e. The only better whole number is base 3, but it requires more transistors to implement, than information capacity gained in the base and efficiency from the proximity to e.Mechanical computers in base 10 (going back to Babbage's engine, among others) are still digital, and still obey the same conditions I laid out before.Indeed, you're very very close to the idea of "digital". You just need to go a few steps further, and consider what it means to be digital -- functionally. Literally: if it quacks like a digital circuit, it is one.Tim

author: james_s
author_rank: Super Contributor
timestamp: October 10, 2017, 05:09:02 pm
content: There are a lot of good answers buried in here although I wonder if the guy is more confused now than when he first askedThe world is inherently analog, but I would describe a digital circuit as one in which we only concern ourselves with discrete states and transitions. Technically every digital IC is inherently an analog circuit but we can ignore that for the most part, we don't care what precise voltage is present on an input or output at any given time so long as it falls within a range defined as either high or low. Many circuits are fairly easy to classify as either analog or digital but there is plenty of overlap. In the end it doesn't really matter, it's just a classification.

author: Beamin
author_rank: Super Contributor
timestamp: October 10, 2017, 06:24:47 pm
content: Quote from: adras on October 10, 2017, 08:18:58 amSo you're a capacitor is half empty kind of guy?

author: Beamin
author_rank: Super Contributor
timestamp: October 10, 2017, 06:27:46 pm
content: Quote from: T3sl4co1l on October 10, 2017, 04:45:45 pmSo why e? For the mathematically illiterate.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 10, 2017, 08:58:55 pm
content: Quote from: Beamin on October 10, 2017, 06:27:46 pmhttps://math.stackexchange.com/questions/446664/what-is-the-most-efficient-numerical-base-systemTim

author: fourtytwo42
author_rank: Super Contributor
timestamp: October 11, 2017, 07:14:37 pm
content: Something I think you may have all missed (I apologize if not) is the role of the dreaded PRODUCT MARKETING!In my experience these people can call black, white if they think it will better attract the consumer.There was a time before humble washing machines contained micro-processors that many goods that contained not a bit, were labelled digital. A bit like the Blue LED fad etc etc.In certain quarters of the audiophile fraternity ANALOGUE is sought after and the presence of any digital components suppressed.

author: Awesome14
author_rank: Regular Contributor
timestamp: October 11, 2017, 07:31:34 pm
content: I'm surprised no one got this one. A digital circuit is any circuit that converts analog to digital or digital to analogedithttps://www.elprocus.com/difference-between-analog-circuit-and-digital-circuit/.An analog circuit has no conversion to digital. For instance, a digital cell system samples the audio voice component and converts it into a digital quantity.The cell phone itself converts the digital quantity back into analog and sends it to the ear speaker, and vice versa for the microphone. The reason for doing this is error checking. The cell phone receives digital packets + a checksum. If the cell phone's calculated checksum is different than the checksum sent by the cell system tower, the cell phone requests that the packets be sent again, and again, until the checksum is correct, which means the packets are intact, the information is correct, and the resulting audio signal will be correct.With analog you can't do algorithmic error checking.Edit: you can do simple algorithmic error correction on analog circuits. In this paper link originally posted above:http://preserve.lehigh.edu/cgi/viewcontent.cgi?article=2035&context=etdI'm not sure I would call the author's idea of analog error-correction the same thing. It seems more like fidelity-loss improvement. It uses sampling and conversion, but it's not linear, so he calls it analog.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 11, 2017, 08:18:31 pm
content: Quote from: fourtytwo42 on October 11, 2017, 07:14:37 pmIs the Moon black or white?It looks "white" against the night sky, but its albedo of 0.12 suggests it's, at best, dark gray.Context matters to visual determinations.Regarding marketing; they're just providing that context. Whether the context is realistic or imaginary, matters not. . .Tim

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 11, 2017, 08:20:58 pm
content: Quote from: Awesome14 on October 11, 2017, 07:31:34 pm[citation needed]Quote[citation needed]In fact, I recently pulled up a cool article about this:http://preserve.lehigh.edu/cgi/viewcontent.cgi?article=2035&context=etdTim

author: Mr. Scram
author_rank: Super Contributor
timestamp: October 11, 2017, 08:27:57 pm
content: Quote from: adras on October 10, 2017, 08:18:58 amTernary computers exist, and something like charlieplexing uses the floating state of pins to do work. I would consider neither properly analog in nature.

author: Mr. Scram
author_rank: Super Contributor
timestamp: October 11, 2017, 08:31:52 pm
content: Quote from: Awesome14 on October 11, 2017, 07:31:34 pmYou're basically saying that a digital circuit deals with digital signals. While true, it doesn't seem to be an answer to the question at all, because the difference between analog and digital is as murky as it was before the answer.

author: vk6zgo
author_rank: Super Contributor
timestamp: October 12, 2017, 02:50:32 am
content: Quote from: adras on October 10, 2017, 08:18:58 amA square wave is a rectangular wave with a 1:1 mark/ space ratio ( 50 % duty cycle.)There are many other types of rectangular waves--------in what way are they not digital?OK, I'm being pedantic, but this is one of my pet hates.Everybody calls any rectangular wave a "square wave", but it is not the case.You are a software person & don't know any better, but others do, & still perpetuate this sloppy usage of terminology.Square waves are a special case of rectangular waves with a different (simpler) spectral distribution compared to other such waves.

author: KL27x
author_rank: Super Contributor
timestamp: October 12, 2017, 05:28:08 am
content: QuoteThis might be a language issue. In many English speaking countries "square" is not just a specific polygon. It is also used as an adjective which means perpendicular, or even as an adjective to mean having 90 degree angles.This could be one of those pet peeves you can let go of.If you want to get really pendantic, voltage and time have no universal scale in relation to each other. Volts and seconds are arbitrary human units. Any "rectangular" half wave can be described as a 3-sided square (ignoring the rise/fall times) by tweaking the scale.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 12, 2017, 06:50:50 am
content: I think he's referring to the class of rectangular wave which is self-inverse. In other words, duty cycle = 50%, and a spectrum of odd harmonics that go as 1/N.I tend to use "square" in the "right" sense (square corners), hence "squaring up" a signal (using an amplifier and clipper, or comparator stage), and neglecting rise/fall times in that sense. It's more accessible (less of a mouthful and more universally understood) than "trapezoidal wave", which would be more strictly correct (but really, the corners are rounded over, but really the..).Tim

author: vk6zgo
author_rank: Super Contributor
timestamp: October 12, 2017, 07:25:19 am
content: Quote from: T3sl4co1l on October 12, 2017, 06:50:50 amI have never heard " square" used in the sense of square corners in over 40 years.The only sense I have ever heard is a rectangular waveform with a 1:1 mark/space ratio (50% duty cycle)(& yes, I neglected to change from 1:1 to 50% when I decided to use duty cycle instead of m/s ratio).The spectrum of such a waveform is different from that of other rectangular waveforms of different duty cycle.I recall having to work out the reason for the difference when I did the "retreads" course to become a Tech Officer with Telecom Aust.The guys that ran the course were very hard on stuff like that.

author: vk6zgo
author_rank: Super Contributor
timestamp: October 12, 2017, 07:38:33 am
content: Quote from: KL27x on October 12, 2017, 05:28:08 amI think you are assuming that I am referring to how the waveform looks on a 'scope.Obviously, the only time it really looks " square " in that sense is if you set the horizontal & vertical controls to look that way.A rectangular waveform with a 50% duty cycle has been referred to as a " square" wave for many decades by people working in Electronics.(How "square "is used by the General Public is beside the point.)OK, it is perhaps a misnomer, but the waveform has a substantially different spectra compared to other such waveforms.If I really want to be pedantic, "pedantic"is not spelled"pendantic".

author: KL27x
author_rank: Super Contributor
timestamp: October 12, 2017, 07:44:43 pm
content: QuoteWe run a board through a jointer and planer to square it. After it's done, the board is square. Perhaps that started out as "in square" or "[having been] squared," before turning into just "square." We adjust picture hanging on a wall until it is square. We square furniture with the walls. And when it's done, we could say, in context, that the bed is square [implicit that it is square in relation to something else].In Australia you guys don't do that, eh?After typing "square" so many times, I am starting to feel like square is a funny looking word.QuoteI find that hard to believe.QuoteThis is also obviously false. See your first post. You wouldn't have a pet peeve over this if you hadn't heard it used to describe other "rectangular" wave forms.OTOH, I could say the first time I have consciously heard "rectangular" as describing an electrical signal was in this thread.QuoteAre you saying "rectangular wave" is the proper terminology? Maybe people got lazy and stopped saying it because it's too many syllables?QuoteI am assuming that is how the name came to be. Why is a signal triangular, sawtooth, trapezoidal, etc? Why do you call a signal rectangular? And why does "square" only apply to "rectangular" waves, if it has nothing to do with the shape of the voltage over time? Why not a square triangle wave (meaning triangle wave which is symmetrical)?When I read Merriam Webster definition of "square wave" meaning only 50% duty cycle, I actually feel like it's wrong. I'm one of the new breed, I suppose. To me they are all square waves, and some have a 50% duty cycle. They're square because they are box shaped and the angles are square, which is irrespective of voltage and timebase settings (within reason... finite rise/fall times and all). I'm happy to evolve the language and fuel your pet peeve.

author: vk6zgo
author_rank: Super Contributor
timestamp: October 13, 2017, 01:35:37 am
content: Quote from: KL27x on October 12, 2017, 07:44:43 pmOK, you got me on that.I meant in an Electronic context, which seemed reasonable considering we are in a thread on an Electronics website.QuoteYes, you are quite correct, I meant that I have never heard it used by people who know how to use the correct terminology.Obviously, I have also heard it used incorrectly.QuoteYou can, of course, make up your own terminology.The only downside is that people may not know what you are talking about!

author: KL27x
author_rank: Super Contributor
timestamp: October 13, 2017, 09:26:16 pm
content: QuoteIf...Quote... this is not a very big risk. I think it's just as likely that people don't assume a "square wave" to automatically have a 50% duty cycle. Funny when you google "rectangular wave," 90% of the links returned are for "square wave." The proper terminology might come back into vogue one day, but the genie is out of the bottle. I was never aware of the proper terminology of rectangle/rectangular wave until this thread!

author: james_s
author_rank: Super Contributor
timestamp: October 17, 2017, 07:41:54 pm
content: Quote from: fourtytwo42 on October 11, 2017, 07:14:37 pmI'm reminded of Blip, "The digital game" which is in fact an ingenious mechanical contraption. The only electrical parts it contains are an LED, resistor, switch and battery. You don't see that sort of complex mechanical engineering in toys anymore.

author: alanb
author_rank: Frequent Contributor
timestamp: October 18, 2017, 12:58:12 pm
content: At what point does your circuit become "digital"? -- When the marketing people say that it should!Digital justifies a higher price than non-digital.You will see that Dyson vacuum cleaners have 'Digital' motors, what ever that means.

author: Beamin
author_rank: Super Contributor
timestamp: October 18, 2017, 10:42:09 pm
content: Quote from: vk6zgo on October 12, 2017, 07:25:19 amYou have never heard of squaring things up? Or square shoulders? Or squaring up to your opponent? Or "these edges are nice and square"? Or "That car looks more square?" I think you are an "L7" Its hip to be square.

author: vk6zgo
author_rank: Super Contributor
timestamp: October 19, 2017, 04:57:02 am
content: Quote from: Beamin on October 18, 2017, 10:42:09 pmI meant "square" corners in the context of waveforms, as I pointed out in an earlier posting.OK, maybe "square wave " for a 50% duty cycle rectangular (or trapezoidal if you like) waveform is no more logical than any other naming convention, but itisthe correct terminology, & should be recognised as such by people dealing with such waveforms.There are many different cases of the correct name becoming that from long usage.For instance, the thing called a Panzer in German is a "Tank" in English, for no real logical reason, apart from being the code name the Brits used for them in WW1.Any Soldier will immediately recognise what you are talking about, but a farmer may think of something else, & an EE involved in RF work, something else entirely.