Damped asymmetrical biphasic sinusoidal waveform

Discussion in 'Homework Help' started by Camiros, Apr 6, 2014.

  1. Camiros

    Thread Starter New Member

    Apr 6, 2014
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    Hi,

    I'd like to generate a damped asymmetrical biphasic sinusoidal waveform but I don't know how to do such a thing. It has to be -50mV to +50mV on few uAmps, both voltage and frequency adjustable.

    It's not an homework I'm not in electronics at all. If someone could provide a simple schematics I could build, I would be very happy.

    Any help is welcome. Thanks !

    Camiros
     
  2. shteii01

    AAC Fanatic!

    Feb 19, 2010
    3,378
    494
    Can you draw a picture to show what it supposed to look like?
     
  3. Aikixtal

    New Member

    Apr 6, 2014
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    Are you looking for a power source that outputs this waveform, or are you looking for a circuit that modifies an input to output this waveform?

    If it is the first case, what kind of timeframe are you looking at for the damping? If it is the second case, are you trying to damp an ac or some sort of pulsed dc input?

    If you are not a student and you do not know how to build such a thing, what are you looking to use the circuit for? The best I can think of off the top of my head is for a sound effect box or some sort of whacky light dimmer.

    Oh, crap, just googled it. Are you looking to build a TENS machine? You know there's virtually no evidence those things work, right? What Avizza (the company touting this "unique waveform") is advertising as a damped asymmetrical biphasic sinusoidal waveform is just a pulsed damped sine wave. The only decent paper I found discussing the actual waveform was written by a veterinarian.

    This smells like pretty bad science to me....
     
  4. Camiros

    Thread Starter New Member

    Apr 6, 2014
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    @shteii01 : this patent does what I'm looking for https://www.google.com/patents/US7509165

    @Aikixtal : I'm looking for a device that modifies an input to output this waveform.

    I frankly don't care about what "kind" of science TENS devices are (and its not a TENS device btw). I'm not here to promote anything, but to answer your message, I simply can witness that this "kind" of science works very well. Try it, you'll see, I was skeptic too. I can't afford buying such a device, and I'm pretty sure the same result could be obtained with quite simple electronics.

    Now regarding what you say (it's just a pulsed damped sine wave), I can add what the book says : "The output of the device is designed to be an LC resonating circuit using microcurrent. When a load (the human body) is placed across the circuit, a unique waveform occurs then resonate with the body as the coil and capacitor of the LC oscillate as described above"

    Then it shows a graphic of a damped sine wave at 100 uS per Div and 204 Volts. On the next page it shows the same wave which amplitude seems to decrease over time.

    Then it talks about SCENAR devices based on Rife discoveries (1940) and Schauberger ones (1900) regarding this specific kind of waveform. A device built up on 1845 that the author tested output the same kind of waveform.

    Any idea on how I could go further ? I tried to find Schauberger papers but failed. Looking at websites on Rife discoveries is still the same problem, seems like everyone keeps the recipe secret, sadly.
     
  5. Camiros

    Thread Starter New Member

    Apr 6, 2014
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    After some research focusing on "Pulsed damped sine wave", I've found some patents that might help understanding what does damped asymmetrical biphasic sinusoidal waveform means and how to replicate that kind of output. It seems to be used in defibrillators devices.

    Please let me know what you think.

    Damped sinusoidal current pulse generator and method
    https://www.google.co.in/patents/US3673437

    Autotransformer assisted resonated energy transfer circuit
    https://www.google.co.in/patents/US3737735

    Waveform simulator
    https://www.google.co.in/patents/US3570143

    Biphasic pulse generator for an implantable defibrillator
    https://www.google.co.in/patents/US4850357

    Damped biphasic energy delivery circuit for a defibrillator
    https://www.google.co.in/patents/US7079894

    Pulsed sine wave oscillating circuit
    https://www.google.co.in/patents/US4328525
     
  6. Camiros

    Thread Starter New Member

    Apr 6, 2014
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    I tried to reproduce US3673437 patent circuit using falstad cirtcuit simulator. I attached txt file you can import.
    It doesn't work very well. No sine wave output and after few seconds running its says "convergence failed".
     
  7. Aikixtal

    New Member

    Apr 6, 2014
    7
    1
    I've had experiences with TENS and piezo, EMS, and other electrostim type devices before. No more effective than placebo. No pain relieved, no accelerated healing, and certainly none of the even more miraculous (and actually offensive) claims were shown to be true. But that's pretty much beside the point.

    Unless you're going to run this thing on AC mains (which is either going to be incredibly inefficient or incredibly dangerous), you first need a circuit that outputs a sine wave from a DC input. That circuit is going to be called an inverter. There are relatively simple inverter circuit diagrams all over google. The sine wave output will only be tremendously approximate unless you go for building a complicated, expensive pure sine wave inverter.

    This poor approximation is what the electrostim companies is spinning as biphasic. They are essentially slapping a bad modified sine wave inverter into a box and selling it. The biphasic part is a cover for the PWM portion of the inverter circuit. Better to call it a 3 voltage modified square wave. The pause in switching when the circuit is outputting 0 volts causes the negative polarity portion of the "sine" to be out of phase with the positive portion. This is probably why they're throwing in the word asymmetrical as well. Neither means much, but they make the product sound all sciency and stuff.

    But anyway. Once you've got your inverted quasi-AC output, it is just run through a damping circuit and a timing switch. The damping circuit will be some sort of RLC circuit. Also easily googleable. As is a timing circuit for firing the inverter, waiting for the wave to damp fully, and firing the inverter again.


    Hope this helps.


     
    Camiros likes this.
  8. Camiros

    Thread Starter New Member

    Apr 6, 2014
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    @Aikixtal : Yep it helps a lot. Thank you very much.

    I was sure this specific wording was a way to hide a more accessible truth. The fact I was unable to find something on this topic on Google seemed very strange to me indeed.

    But once again, the device on the Avezzia patent is not a TENS device. And its not just about a device but a method. Have a look at this book 978-1453649169.
     
  9. Camiros

    Thread Starter New Member

    Apr 6, 2014
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    Following Aikixtal explanations I was able to reproduce something very similar to what I need but I have some issues.

    First I'd like to get rid of a transformer, it's a huge component and I'd like to have something smaller. Is there a way to get the same behavior but with smaller components ?

    Second I'd like to correct the output to get the exact same shape repeatedly but I don't know how to calibrate. I need to adjust the values of the timer capacitor and resistor but I don't know the formula. If i skip the timer and plug the DC out directly on the transformer, the resulting shape seems correct.

    I used falstad circuit sim, but if anyone knows a better software to do the work i'd be happy to try it. I tried LTSpice but was unable to find a transformer on its libraries.
     
  10. Aikixtal

    New Member

    Apr 6, 2014
    7
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    That's a pretty sweet first cut. The math you need is at
    http://en.wikipedia.org/wiki/RC_circuit

    How's your diffEQs?
     
  11. Camiros

    Thread Starter New Member

    Apr 6, 2014
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    Thanks for the link.

    To be honest, I'll try to do my best at understanding it, but I'm not in electronics at all, I never had any training on diffEQ (I suppose you mean differential equations ?), and most generally no training in maths at all.

    I've done some tests and researches since yesterday and I think I don't need a transformer, only a DC amplifier. As it seems the output voltage should be 204 Volts but on few uAmps, a 9V battery should be enough. (I've read that the more we amplify voltage the less we can output amps). Does it sounds right ?
     
  12. Camiros

    Thread Starter New Member

    Apr 6, 2014
    8
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    Here is a circuit that outputs 223V from a 9V battery.
    The thing is I don't know if it can be done in reality. Are there any components that can support this voltage ? Won't they burn ? Or maybe it's a simulator bug ? What do you think ?

    Honestly I just play with components values and look at the output, I'm not doing any maths.
     
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