Analogue vs Digital Electronics

Discussion in 'General Electronics Chat' started by Shah_Key, May 11, 2013.

  1. Shah_Key

    Thread Starter New Member

    Jan 8, 2013
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    Hello

    I was wondering what the difference is between using an analogue electronic circuit against a digital electronic circuit? What the benefits and disadvantage is between the two.

    I know the basic reason behind it but I would like to develop my knowledge a little more. I think digital electronics such as using a microcontroller is better than analogue circuits.

    I am trying to look for reasons for why analogue might be a better choice than digital.

    Thank you in advance
     
  2. crutschow

    Expert

    Mar 14, 2008
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    Electronics is becoming more and more digital because it allows precise manipulation and storage of the data. Once data is in digital form, it can be stored forever in digital memory.

    Analog is still required for initial processing of many signals, such as RF and low level sensor signals, since present A/D converters don't have sufficient sensitivity/speed to deal with those signals directly. But typically, as soon as the analog signals are in a form that can be converted to digital, they are for further digital processing.

    Thus, for example, a digital TV set has analog circuitry in the RF input to amplify the signal, but as soon as the digital modulation signal can be extracted, the rest of the TV electronics uses digital processing.

    Hobbyists often use op amps and other analog circuits for electric projects since various signal generation and processing tasks are simpler to do in analog.

    My motto is generally to do as much as of the job in digital as possible, unless it is too difficult or complex.
     
  3. MrChips

    Moderator

    Oct 2, 2009
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    First let me make one clarification if not to confuse you even further. With respect to electronics, all digital circuits are analog. But analog circuits are not digital.

    What do we mean by analog vs digital?

    Analog electronics operate in a continuum of currents and voltages. For example, if our circuit is powered with a 5VDC power supply, we may experience voltages over the entire range from 0V to 5V.

    A digital circuit is hardly different. If the output of a digital circuit has to change from 0V to 5V, the circuit still has to traverse the analog range from 0V to 5V. It cannot suddenly go from one voltage to another.

    By digital, we mean that we will consider any voltage below, let us say 2.5V to be a logic LOW, while any voltage above 2.5V to be a logic HIGH. The circuit is still an analog circuit. It is our interpretation of the information that is considered digital. Hence digital means taking a continuum of analog voltages and narrowing it down to mean only one of two things, i.e. it becomes a binary value.

    Hence, to answer the question of which is better, analog or digital, there is no appropriate answer.

    Analog circuit design has relevance in a given application.

    Digital applications has relevance in its applications. You cannot make valid comparisons. You need to compare the specific applications.

    Here is a simple analogy. Suppose you have a bushel of apples and I asked you how many apples do you have? You can give me the answer by counting the number of apples in the bushel.

    You could also tell me how much apples you have by weighing the bushel and giving me its weight.

    One method and its answer may be preferred depending on the type of information I am seeking.

    One answer is quantized, i.e. it gives me a discrete number (integer value).
    The other answer is an aggregate, i,e, it gives me the total weight which is not a discrete number (non-integer value).
     
    Last edited: May 11, 2013
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  4. WBahn

    Moderator

    Mar 31, 2012
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    Or I could tell you, "Weren't you listening? I have ONE BUSHEL of apples!" :D
     
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  5. MrChips

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    I just knew you would say that!;)
     
  6. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    Now I'm confused: are apples digital or analog?

    Do androids dream of electric sheep?
     
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  7. gerty

    AAC Fanatic!

    Aug 30, 2007
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    And do pears come in pairs....or can you get one at a time, but if you can is it a pear?





    Sorry..couldn't resist :)
     
  8. WBahn

    Moderator

    Mar 31, 2012
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    Depends on if it is an anapple or a digapple.

    Do electric sheep run scared?

    And what to I-Phones dream of?
     
  9. tindel

    Active Member

    Sep 16, 2012
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    This is a horrible misconception - and I think it stems from marketing teams focusing on pushing 'digital' products in the 90's and early 00's. You can do almost anything in the analogue realm that you can do in the digital.

    These days many of the analogue systems of the past have been converted to digital systems mostly due to size restraints and ease of processing data. Digital is very important, but it's not better or worse than analogue.

    Examples:

    • Digital phones are better than analogue phones due to size constraints.
    • Analogue stereo systems are typically better than digital audio systems.
    • Professional photography is better in analogue.
    • Oscilloscopes are a good example - both the old analogue scopes and newer digital scopes have their advantages. I use both frequently because they both have different strengths and weakness, and where one struggles, the other usually excels.
    • Almost all sensors (temperature, humidity, etc) use analogue and convert to digital
     
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  10. ScottWang

    Moderator

    Aug 23, 2012
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    1. The needle watch is analogy, the lcd watch is digital.
    2. The needle meter is analogy, the lcd meter is digital.
    3. Walkman is analogy, Ipod is digital.
    4. A type for type recorder is analogy, A CD for CD player is digital.
    5. City telephone is analogy, cellphone is digital.
    6. Analogy as how much, digital as how many.

    Different people look the values of stuff could be different, like as a needle meter, that is analogy, everybody look the values of stuff are the same, like as a lcd meter, that is digital.

    Using the digital logic IC to design a Digital circuits, that is basic logic, a microcontroller including software and hardware, the hardware is assembly from many basic logical gates, it's more complicated, but you can do things much more and more, and the circuit can be more intelligence, more smart, you can do whatever you like.
     
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  11. Shah_Key

    Thread Starter New Member

    Jan 8, 2013
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    Thank you everyone

    The main reason i wanted to know was to find out reasons why using a 555 timer might be better than using a microcontroller?
     
  12. MrChips

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    In robotic systems, the mechanical motion is performed with analog amplifiers and motors. While the position sensors and the motion controllers all use digital components the final positioning and feedback control systems are performed with analog amplifiers and motors.

    For example, the precise positioning of the laser diode and optical sensor of a compact disc (CD) reader is done with analog electronics.
     
  13. MrChips

    Moderator

    Oct 2, 2009
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    Well, why didn't you ask that question in the first place? That has nothing to do with the pros and cons of analog vs digital.

    Is a 555 timer an analog or digital circuit?

    Is a 74123 monostable multivibrator circuit an analog or digital circuit?

    To answer the question of 555 vs microcontroller, there is no clear answer.
    There are too many variables and it depends on the application.
     
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  14. WBahn

    Moderator

    Mar 31, 2012
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    Two things:

    First, why did you ask some vague super generalized question if you wanted something as specific as this. This would be like asking if gasoline is better than diesel when what you are really interested in is whether a pickup is better than a station wagon.

    Second, like the pickup and the station wagon, even the more specific question is way to broad and impossible to answer without much more specific context.

    Why do you imagine that they make both 555s and microcontrollers? Because each have their strengths and weaknesses. There are many problems for which you would employ a 555 right away, others in which you would turn to a microcontroller, and for most problems you would use neither because something else entirely is better suited.
     
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  15. ScottWang

    Moderator

    Aug 23, 2012
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    NE555 can be using over 100 different applications, uC can be using over 10000 different applications and more.

    NE555 has three pins could be output the signal, uC as AT89C2051 has 15 pins can be input or output signal.

    The uC can be communicate with PC, but NE555 can't do that.

    When you using NE555 to do as timer, but it's not stable and not precisely, uC using crystal to generate the pulse and can be control by software.

    So it's depends on what you want to do, because they are designed for different purpose, the easy things you may using NE555 and the complicated things that you will need to using uC.
     
  16. MrChips

    Moderator

    Oct 2, 2009
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    If I were marooned on a remote island and I happened to have a collection of resistors, capacitors, LED, battery, 555, microcontroller, and I had to make a flashing beacon, I would be able to do it with the 555 and not the microcontroller.

    Application, application, application.
     
  17. tindel

    Active Member

    Sep 16, 2012
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    So here's the real question:

    What is your application, and how can we help you decide to use a 555 or a uC?
     
  18. Shah_Key

    Thread Starter New Member

    Jan 8, 2013
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    The application is a liquid detector, please see the image.
    [​IMG]

    I could have used a MCU but I found it easier using a 555 timer. I just want some help justifying how a 555 timer could be a better choice rather than saying it just easier.
     
  19. tindel

    Active Member

    Sep 16, 2012
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    I think you figured that out yourself!

    Why is it easier?:
    No software involvement
    Cheaper parts
    Fewer parts
    Smaller board
    Quicker to market
     
  20. MrChips

    Moderator

    Oct 2, 2009
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    Well, there you go. How can you come up with a solution simpler than that?

    The one thing I would change is the 555. Replace the NE555 with a CMOS version such as TLC555 or LMC555.

    Is K1 a self oscillating buzzer or is it a piezo-electric transducer?
     
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