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Drawing Waveforms or how to draw waveforms

Discussion in 'General Electronics Chat' started by walters, Nov 16, 2005.

  1. walters

    walters Banned

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    Nice pictures but there is no way i could write code in matlab i need something really easy that has a Arbitrary function generator with waveform editing and shaping editing so i can plot it out in Voltages VS time with gradules

    The New Arbitrary function generators come with software to edit and Draw new waveforms and download or print them out so i can have alot of different waveforms,shapes,curves,slopes etc.

    I wonder if there is Software Abritrary Function generators that have waveform editing and shapes but nothing hardware just pure software this would help me out alot
     
  2. _3iMaJ

    _3iMaJ New Member

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    Writing an arbitrary function generator in MATLAB would be very easy. You could implement it using a GUI if you'd wish.
     
  3. bloki

    bloki Member

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    Yes there are a lot of programs that can draw a functions. These are math programs like MATHLAB, MATHCAD, MATHEMATICA or some simpler specially designed for function drawing. But to be able to use them you should first know the mathematical equation of your function. To be able to understand drawing you should be familiar with the functions.
    Programs don't have pulldown menus for it.
    How is weather in Irvine today?
     
  4. dave

    Dave New Member

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  5. walters

    walters Banned

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    MATHLAB, MATHCAD, MATHEMATICA

    I don't know math so i can't use these programs

    What other programs out there that don't use math but have a arbitrary function generator built in without any math at all i want to get away from the math programs and use a simple easy abritrary function generator in software with waveform editing and shaping function with no math at all
     
  6. jrz126

    jrz126 Active Member

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    I'm very confused...the reason you want these plots is so that you can learn how to measure them? (amplitude, period...ect).
    But yet you dont want to learn the math behind the functions in order to draw them?
    If you understand the math behind the functions, I would think it would be really easy to understand how to make the measurements.
     
  7. walters

    walters Banned

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    Yea but writing Code is like being a programmer im not a programmer and not really into math im not that smart so i need a learning tool and waveform drawing editing program . Programmer and math is just to hard for me im just into electronics not math or programming code
     
  8. bloki

    bloki Member

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    Dear Walters,
    Your approach in understanding electronics is leading me to a conclusion that you can easily become a brain surgeon.
    For starting try some knitting first.
    Regards
    P.S.
    How is weather in Irvine today?
     
  9. Styx

    Styx Active Member

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    if you find maths hard then electronics is going to be even harder.
    You need to take a step back and think if electronics is for you.

    There are going to be time when you have to drop down to mathematics to go over something to justify it.

    Maths is everything, failure to understand even the the basic trig and algebra is asking for problems

    Also does it really matter if you program? Nigel does PIC stuff (which is alot more software-based then MATLAB) but he does electronics.

    MATLAB is a scripting language and it has been written for use by engineer, thus its actual syntax is actually very BODMAS and general math-syntax friendly.

    I am not a programmer, I work with opamps and opamps are analogue devices and maths is needed daily.

    What you are describing that you want can be solved in 1/2day working with MATLAB/Octave or any other thing. Say take a day to get to grips with it.

    How many days have you wasted here just wanting something given to you?


    What is the slew rate of a sine wave?
    what do you do? do you measure it or do you just differentiate it?

    beleive me for a pure sine wave differentiation is alot quicker (its cos btw)
     
  10. mstechca

    mstechca New Member

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    Why do you care?
    The only way you can do electronics without math is to get someone else to do the math for you.

    I hope you went through high school, because there is some math in there that you could have learned.

    and being a programmer is an asset to loving electronics, but it is not necessary, if you build basic circuits.

    Start learning QuickBasic. That is one of the easiest programming languages out there. You can even use it to make sinewaves.

    So PLEASE learn a bit more math before continuing, or I can guarantee that your next (several) circuits will malfunction.
     
  11. _3iMaJ

    _3iMaJ New Member

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    A very good understanding of mathematics is very cruicial to being a successful (gasp, even competent) electronics person/ electrical engineer. By the time you graduate from college you've had almost as much math as a math major, by the time you finish a Master's its quite possible to have had more math...

    Math and electronics go hand and hand, almost anything conceivable can be described mathematically...
     
  12. walters

    walters Banned

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    Can the New Digital Oscilloscopes measure the periods,duty cycles,pulse widths, time constants, 10-90% perecentages,rise time and fall times
    With Markers? or automatic? i can just press a button and it will tell me the period, duty cycle, pulse width, time constant, 10-90% voltages VS time, rise times and fall times? are these function automatic in digital oscilloscopes they have automatic buttons presets ?


    I get around math by using the internets online Electronics Calculators
    they have almost everything on Electronics Calculators so i really don't need to get a math degree because the Formulas are in the calculators and all u do is just put in the Values really easy for a type of person like me thats not math brain
     
  13. Styx

    Styx Active Member

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    :roll: :roll: :roll:

    I really do give up with you :roll:

    just because you know where to get calculators from doesn't mean that is all you need.

    YOU NEED TO UNDERSTAND THE BASICS ON MATHS!!!!!!

    everyone here has said that
    oh and to yr quest yes modern scopes do provide "measurement" functonality, TEch TDS3014B is an excelent scope at £5,000 BUT it is ONLY useful if you know what you are measuring since it is actually very dumb and you need to ensure you have triggered the scope at teh relevant time

    so yr choice. GCSE maths or £5000 [/b]
     
  14. bloki

    bloki Member

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    What is the purpouse of measuring those parameters if you do not even understand what they are? Or you are just too lazy.
     
  15. walters

    walters Banned

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    I'm not lazy is just i don't know what i am doing to i need to practice on measuring these parameters i was just wondering if a Digital oscilloscope does it for me so i know for sure im doing it right.

    I just use the calculators as a tool yes i don't know everything but it does help me get by without knowing alot of math im just a basic electronics guy

    If i get a software waveform editor and shaper with a digital oscilloscope software i think it would make the parameter measurements easier i guess
     
  16. DigiTan

    DigiTan New Member

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    If you weren't so busy bullying walters, you'd know that he is new to electronics and is just looking to get started on the basics here. The disrespect and cynicism on this board is getting out of hand again, and personally, that's why I quit coming here a few months back. Next time you need walters to convince yourself you're not a loser, kindly "get off his nuts" as we say in America and keep it to yourself.
    ------------------

    To answer the question: yes a digital oscilloscope can provide those measurements and in fact, there are virtual instrumentation programs that can export those parameters directly to a PC. Generally though, you don't need them because they are extremely easy to calculate using only your eyes and maybe a 4-function calculator. The scope I use most often is the HP 54600B with an IEEE 488 bus for virtual instrumentation, and it's loaded with all the features. They also give a pair of horizontal and vertical lines (cursors) that essentially act as yardsticks for more accurate time & voltage measurements. To summarize the parameters you mentioned:

    period - Zoom in/out until you can see 1 full wave cycle. The period is: end time - start time.

    duty cycle - You usually only see this associated with rectangle waves. The duty cycle is the percentage of the time the wave is high. If you're rectangle wave is imperfect and has a noticebe rise/fall time, you measure from the points where the wave is at 50% peak voltage. Otherwise, you measure from rising edge to falling edge, and so on.

    pulse width - Same as duty cycle except it's expressed in seconds instead of a percentage.

    time constant - The meaning of this varies. Generally, you see this term associated with a source-free RC or RL systems, which implies you're watching an exponential decay. My scope does not measure this explicitly but you can measure it like I did in the "Discharging Effects" thread.

    rise times and fall times - For pulse trains, the rise time is the time it takes for the signal to go from 10% to 90%. Likewise, "fall time" is the time to get from 90% to 10%.
     
  17. walters

    walters Banned

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    Thanks DigiTan for the information

    Time constants measured only for exponential decay and Curves? what about the rise time or fall time can i measure the time constants from a rise time or fall time or a curve? mostly in my book time constants says 0-63% percentage? i think time constant is only applied to Triangle waveforms or exponential curves?

    When measuring Percentages does it mean Voltage percentage or Time percentage?

    Is time constant and duty cycle both measured in percentages but what kind of percentages time or voltages?

    example measuring duty cycle first have to measure the pulse width so if the pulse width of the square wave is lets say 40us

    Duty cycle percentages:
    What is 10% of 40us? 4us
    what is 20% of 40us? 8us
    what is 30% of 40us? 12us
    what is 40% of 40us? 16us
    what is 50% of 40us? 20us
    what is 60% of 40us? 24us
    what is 70% of 40us? 28us
    what is 80% of 40us? 32us
    what is 90% of 40us? 36us

    Rise time is 0%-90% so the rise time is 36us
    Fall time is 90%-0% so the fall time is also 36us

    If the exponential decay or rise or fall time was 40us
    Time constant is 0%-63%

    63% of 40us is ? 25.2us
     
  18. DigiTan

    DigiTan New Member

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    Yep, the time constants are generally applied to exponential decays, especially in digital switching. To find the time constant if you already know the fall-time for example: you first take the initial voltage (Vinit), then you record the 90%-Voltage time and the 10%-Voltage time (T0 and T1). This gives you two equations:

    V(t=T0) = Vinit*e ^ (-T0/RC)
    V(t=T1) = Vinit*e ^ (-T1/RC)

    ...where RC is unknown, and "V(t=T0" means "the voltage after T0 seconds have passed." Since you have only 1 unknown value (RC), you only need 1 equation, so let's actually trash the 2nd equation. Then, to get rid of the e, multiply both sides by LN() to get...

    LN([V(t=T0)/Vinit]) = - T0/RC

    ...then divide T0 and T1 to move them to the left-hand side, so you get...

    LN([V(t=T0)/Vinit])/T0 = - 1/RC

    ...then multiply both sides by -1 and take the reciprocal to get "RC" out of the denominator...

    RC = - [[V(t=T0)/Vinit])/T0]^-1
    -----------------
    Your book is correct, the time constant tells you how much time it takes to swing the voltage 63.2%. Since exponential curves are sometime overly-complicated, you can simplify them by replacing them with a constant slope (triangle wave), but you loose a lot of accuracy, IMHO.

    The percentages are applied to the voltages. So if your peak voltage is 5V and is decaying exponentially, you find the time constant by looking at where the voltage reaches 1.84Volts (5Volts*[100%-63.2%]).

    the time constants are always measured in seconds, and are often prefixed depending on which is more convenient (nanoseconds, milliseconds).

    You are correct on duty cycle. Likewise, you can take: [total "on time"/pulse width]*100 to get the percentage.

    The rise/fall time is 10% to 90% and 90% to 10% of the max voltage. So the rise time would be 32us. We also can the rise/fall time the "slew rate" or "slew time"--usually when they are equal or pretty close to equal.

    If the rise/fall/slew time is 40us, we can use to algebra above to solve the time constant.
     
  19. mstechca

    mstechca New Member

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    Why do you care?
    Depends on the part of a circuit you are dealing with.

    duty cycle is in normal percentages (just like what tax is measured in)
    time constant?
    well "time" is measured in any kind of seconds. you can even go to microseconds.

    Duty cycle determines the "balance" of a waveform. If the logic high and logic low in a square wave are equal in time, there is a 50% duty cycle.
    If the logic low is on 90% of the time, then we could say we have a 10% duty cycle or a 90% duty cycle (depending on which logic state you refer to).

    :D :D :D
    YAY! you learned some math!!!

    Rise time and fall time depend on the circuit.

    I think you need to post an oscillator circuit and ask these kind of questions about it, or you will get yourself confused with the facts. In fact, you are already confused with the math, because you are trying to memorize words, when there is nothing to apply it to.

    Am I making sense to you? :wink:
     
  20. tkbits

    tkbits Member

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    More likely he learned how to use the % key on some calculator.

    Percentages = fractions

    I don't get the sense that he understands ratios or pure fractions. Percent means 1/100 (or hundredth). It is not a measured unit like seconds. It is a derived, calculated number that tells you the relative sizes of two things. When it's not derived, it's an adjustment factor - you use it to derive other values. It's usually not "measured" because it's a statement about relative sizes.
     
  21. Styx

    Styx Active Member

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    Last edited by a moderator: Dec 26, 2013

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