Pulse Generator Theory

Discussion in 'Homework Help' started by Amryan, Aug 22, 2013.

  1. Amryan

    Thread Starter New Member

    Aug 14, 2013
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    Hi guys,

    I need help for making a pulse generator. Do you have any theory about voltage pulse generator? an equivalent circuit? How to vary the time, vary the voltage output etc.

    cheers,
     
  2. eman12

    Active Member

    Oct 26, 2007
    41
    0
    Hi Amryan,

    What you are meaning & What you exactly want to do?
    I can help you but you should be more clear please. There are several different ways/Methds to generate Pulses with variable Frequency an output level. But if explain your goal I can offer the suited ones.
     
  3. Amryan

    Thread Starter New Member

    Aug 14, 2013
    16
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    Hi eman12,
    So my professor gave me a project about transferring a voltage pulse through a 10kV cable using a contactless capacitive coupling sensor... He want me to build an AC 50-100v output pulse generator that can control the pulse width and the time rise and fall time. I have zero knowledge about pulse generator.

    Cheers,
     
  4. tindel

    Active Member

    Sep 16, 2012
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    193
  5. Amryan

    Thread Starter New Member

    Aug 14, 2013
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    I do want to study.. Thats why I want to know the basic theory, also the equivalent circuit, and which one should we replace if we want contol the pulse width or something...
     
  6. eman12

    Active Member

    Oct 26, 2007
    41
    0
    When you say "AC 50-100v output pulse generator " I assume you need an oscilator, So what about using a function generator or an PWM chip?
    Something like TL494?
     
  7. eman12

    Active Member

    Oct 26, 2007
    41
    0
    TL494 is able to generate a continuse pulse width signal.
    50-100V output is not so safe. please be careful. But anyway you can amplify the output of your function gnerator or PWM chip Simply.
     
  8. Amryan

    Thread Starter New Member

    Aug 14, 2013
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    So I think it's not continues because, I'm gonna use Time domain reflectometry to analyse the cable. I think I have to assume that it's only use single or double signal only. and is it unsafe?? can you be more elaborate why is it unsafe?
     
  9. wayneh

    Expert

    Sep 9, 2010
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    You can definitely feel a 50-100V pulse, even if it's just one brief pulse. Under the right conditions it could be dangerous.

    A supply capable of delivering that pulse is also dangerous. Creating the pulse by using a transformer to step up a smaller pulse is safer than a continuous 100V supply.
     
  10. Amryan

    Thread Starter New Member

    Aug 14, 2013
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    Thank you for explaining. There is another question, what are the conditions that might be dangerous. Because this pulse generator will be implemented on an overhead high voltage transmission line with 1 meter distance between the cable and the device
     
  11. Amryan

    Thread Starter New Member

    Aug 14, 2013
    16
    0
    So I think it's not continues because, I'm gonna use Time domain reflectometry to analyse the cable. I think I have to assume that it's only use single or double signal only. and is it unsafe?? can you be more elaborate why is it unsafe

    is there any ways to help me??
     
  12. wayneh

    Expert

    Sep 9, 2010
    12,100
    3,034
    When there is any direct human contact. A zapped finger is a mild hazard (because you might jerk your arm into your coffee pot, cutting your arm and scalding your legs with hot coffee). A zap across fingers on opposite arms is a bit higher risk, since the current passes through the body and across the chest. Holding a good large conductor with sweaty hands would increase this current far more. Having the conductor in your mouth could send current through your skull and maybe even kill you.

    My point is, the risk is small if reasonable safety precautions are taken. But under conditions that are unlikely not impossible, 100VDC could be fatal. Use insulation, isolation from intruders, fusing, warning signs, whatever you can think of. Imagine a having a dog or a 2-year old running around your equipment - how would you protect them from sticking a live wire in their mouth? A moments thought and attention to safety should eliminate the majority of the risks.
     
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  13. Amryan

    Thread Starter New Member

    Aug 14, 2013
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    that's reasonable.... That's why I'm not sure about how much the Voltage amplitude and the pulse width... Because I need to simulates in ansys whether the pulse will successfully transmitted or not. That's why I need the schematics so I can try it first

    So... is there anyone would help me???
     
  14. tindel

    Active Member

    Sep 16, 2012
    568
    193
    Seems like someone posted 5 complete schematics for pulse generators... They probably need some modification to supply 100v DC and to update obsolete parts, but with you're recently acquired education the mods shouldn't be too hard.

    This is not "do your homework for you forum"
     
  15. Amryan

    Thread Starter New Member

    Aug 14, 2013
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    Yes... I know there are complete schematics, but i want to know the basic circuit and how they works so I will know which part should I change. And FYI, it's 50-100 AC input not DC...
     
  16. tindel

    Active Member

    Sep 16, 2012
    568
    193
    Every single one of the tektronix documents of that era has a complete theory of operation that details the function of nearly every part, as well as includes a detailed parts list. If you have specific questions, or can't work out the math, then ask questions, but don't expect us to be able to give you the 'answer' or a schematic that meets all of your requirements. You're the EE - or about to be... go do some research!!!

    There are MANY ways to make a 100Vac or dc pulse generator... my solution is just one of those solutions... eman offered a different solution... you could use a commercial pulse generator and amplify the pulse, you could use a 555 chip to create the pulse and amplify it... the list could go on and on.
     
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  17. Amryan

    Thread Starter New Member

    Aug 14, 2013
    16
    0
    Thank you for your guidance and explanation...
     
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