learning eagle software?

Discussion in 'General Electronics Chat' started by Mathematics!, Dec 22, 2009.

  1. Mathematics!

    Thread Starter Senior Member

    Jul 21, 2008
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  2. SgtWookie

    Expert

    Jul 17, 2007
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    You didn't give it enough time to start, you didn't specify a max timestep, and you didn't use startup.
    Right-click on .tran
    Change the line to:
    .tran 0 21mS 0 2uS startup

    Also, it isn't Eagle, it's LTSpice.
     
    Last edited: Dec 22, 2009
  3. Mathematics!

    Thread Starter Senior Member

    Jul 21, 2008
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    sorry about the mix up I was using both and meant LTspice when writing this thread...

    But I tried what you said and I still don't see the sine wave...???
    Attached is a screen shot of it.
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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    See that big blob of red at about 20.5uS? That's where your sinewave is. It'll be at around 57MHz.

    Expand just that area by left-clicking at the top right edge of the waveform display (near 400mA) and dragging down to where the red blob starts.

    You'll have to zoom in several times to see the sine wave, it's oscillating at a pretty good clip.

    Once you've zoomed in on just the sinewave, you can right-click in the plot box, and select the bottom item - then choose FFT. Do the FFT on Ie(Q1), and you'll see the frequency spectrum display.
     
  5. Mathematics!

    Thread Starter Senior Member

    Jul 21, 2008
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    Few questions on the above.
    I have V(n001) , V(n002) , I(V) , I(C3) , ....etc

    Which one of them is the is the sinewave for this ossilation circuit?
    I.e should I be looking at the battery voltage fluctations would that be equivalant to the ossilating sinewave V(n001)....
    Also is their any component that you can use for a antenna? I see no ant symbol ?

    Is their any way to get a better looking sinewave maybe varying the time you gave me will do it?

    Thanks attached is the screenshot of what some of it looks like....
    I do see somewhat of a sinewave emerging?
    Curious to know if you had a reason for .tran 0 21mS 0 2uS startup ( the 21mS and 2uS )?
    If the wave is 57Mhz => period is going to be 1.7543859649122807017543859649123e-8 = 17.5uS
     
    Last edited: Dec 22, 2009
  6. SgtWookie

    Expert

    Jul 17, 2007
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    Place your test probe at the junction of L1, collector of Q1 and top of C1.

    The power source is a perfect source. If you give it a value of 6 and no internal resistance, it will always put out 6v - unless you try to connect both ends of the source with a wire; then you will receive an error message.
    Use a fixed resistor for simplicity. However, this is an oscillator, not a transmitter. A resistor would simply load it down.

    Keep selecting a smaller area of the sinewave; you will see what looks like a very nice sinewave emerge.

    Right now, it just looks like a band of noise. You need to select a smaller segment to look at.
    I ran the simulation myself. When it didn't oscillate, I extended the time and gave it a timestep limit. Mine started oscillating just before 21mS, which is why I had you stop it there. Otherwise, it will take a long time for the simulation to run, and use up a LOT of disk space.

    Keep expanding the waveform and see.

    Try my version of it (attached) - I cleaned up the schematic a bit, and added a SigOut label on top of C1

    Using labels like that is a big help over just seeing V(n003) or the like on the plot. V(sigout) has far more meaning.
     
  7. Mathematics!

    Thread Starter Senior Member

    Jul 21, 2008
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    Ahhhhhh, I got it.

    Didn't know you had to zoom in so much before it becomes looking like a sine wave.

    Is their anyway to set it so it is already zoomed into the sinewave.
    Would this be controlled by the max timestep
    what is exactly the timestep for 2uS and all the other setting for in transient tab?
    .tran 0 21mS 0 2uS startup

    I do get different outputs if startup is not check off ...etc

    Thanks for your help
    LTSpice can be convient instead of having to always test the design by building it on solderless breadboards.....!!!

    Question
    I have been designing all kinds of ossilator circuits. And it occured to me that ossilator circuits are nothing but circuits that convert DC to AC.
    Which is the equivalent of an inverter maybe the output of the ossilator would need to be steped up by a transformer.

    Like 9vdc --60hz ossilator --- step up transformer --- 120vac 60hz

    If this is all that inverter circuits are then cool.
     
  8. SgtWookie

    Expert

    Jul 17, 2007
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    You already knew that 57MHz would have a mighty small amount of time between cycles. Have another look at the plot pane with just SigOut displayed, and zoom in on just one complete cycle. Then subtract the time from the first positive zero crossing from the end positive zero crossing, and you'll see it's pretty close to what you expected.

    You can tell it to start saving data at a time other than zero, but you might have to adjust the stop time.

    no.
    This is explained in the Help file.
    It is always a good idea to use the Startup option if you are attempting to simulate an oscillator or astable multivibrator. Otherwise, you may wind up with strange results.

    That's the idea. It is not perfect, but it is far faster than building with actual components - and you can get a good idea of what to expect when you do use actual components.

    Pure sinewave inverters are very inefficient. They wind up dissipating a lot of power in the drive transistors as heat.

    More efficient inverters use a type of PWM to approximate a sinewave. The approximated sinewave can then be filtered to approach a true sinewave.

    Research Class D amplifiers to get a better idea of what I'm talking about.
     
  9. Mathematics!

    Thread Starter Senior Member

    Jul 21, 2008
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    As for the eagle

    I will do some reseacher

    But curious can PWM with a timer or AVR chip be enough to make these efficient inverters ?
    Thanks
     
  10. lmartinez

    Active Member

    Mar 8, 2009
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  11. SgtWookie

    Expert

    Jul 17, 2007
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    Yes.

    You'd need peripheral hardware, of course - but with a uC, you could use a voltage divider or current sense resistor to monitor the output and make adjustments as necessary.

    You might find this interesting:
    http://www.tinaja.com/magsn01.asp
     
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