Boost Converter Help

Discussion in 'General Electronics Chat' started by ItsTheFark, Jun 14, 2009.

  1. ItsTheFark

    Thread Starter Member

    Jun 14, 2009
    24
    0
    I am new to the world of electronics and creating circuits etc. etc. and I wanted to make this Boost Converter off this website http://www.anothercoilgunsite.com/nf-portable-construction.htm

    I have been having trouble understanding what half the symbols mean, for example:

    The resistor symbol with the arrow going through it

    The single black rectangle that says +12V next to it

    The non-regular pentagon on its side that says V_Switch

    The grounded symbols off of it... does that just mean a loose wire?

    The larger circle with the + and - in it

    I know this is a big request but any help is appreciated, because as i said, im new to this but i have a desire to learn it.
     
  2. DrNick

    Active Member

    Dec 13, 2006
    110
    2
    Most of the symbols you are confused about are NET labels. They are just names for certain wires in the circuit.

    The resistor with an arrow thru it is a potentiometer. It is a resistor that you can change by moving a mechanical wiper by means of a dial that you spin.

    The large circle with the + - in it is just a voltage source.
     
  3. ItsTheFark

    Thread Starter Member

    Jun 14, 2009
    24
    0
    What about that pentagon on its side with the V_Switch next to it?
     
  4. DrNick

    Active Member

    Dec 13, 2006
    110
    2
    That is also a net label.
     
  5. DrNick

    Active Member

    Dec 13, 2006
    110
    2
    After looking at this circuit a bit further, I have found it to be pretty crummy. It is an open loop boost converter...therefore the voltage at the output can be made obscenely high depending on how you set the duty cycle of the 555 timer (using the potentiometers. It would be better to use some sort of zener clamped charge pump with a bank of capacitors to discharge when you fire the gun...or whatever it is you're trying to build.

    This may be an "unsafe" project for you to attempt if you hare having trouble reading net labels...
     
  6. ItsTheFark

    Thread Starter Member

    Jun 14, 2009
    24
    0
    Safety is not the issue... With several family members being electricians safety is the one thing i actually know.

    Zener.. pump... wha? Sorry that just blew right over my head.

    Before i actually went into this i was going to just use some 9 volt batteries set up parallel, DC/AC transofrmer, AC/DC voltage tripler into the capacitor bank.
     
  7. DrNick

    Active Member

    Dec 13, 2006
    110
    2
    using a low voltage inverter, and a voltage trippler may be better for you, as the high voltage side will be isolated from all of the low voltage circuitry. In the boost converter the switch that is being driven by the 555 timer (which is a crummy way to do it by the way) has 200+ volts at its collector. SO if there is a failure, transient high voltage will be everywhere on your board = bad news.
     
  8. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You might want to look at Ronald Dekker's "Flyback Converter for Dummies" page:
    http://www.dos4ever.com/flyback/flyback.html
    It's a good intro to boost and flyback converters, and how to make your own inductors and transformers for these projects.
     
  9. ItsTheFark

    Thread Starter Member

    Jun 14, 2009
    24
    0
    So basically your saying that my idea is better than a boost converter because it would isolate the high voltage to just the capacitors? Also i looked at that site, thanks it cleared some stuff up.

    And lets say i decide to do my origional plan with the DC-> AC converter, and voltage tripler...
    A) How will i know when its done charging
    B) Will it even stop charging?
    C) Could i get an estimation of how long it would take using a 9 volt battery, using the voltage tripler, and fully charge 1 1200uF 450V capacitor?
     
    Last edited: Jun 14, 2009
  10. ItsTheFark

    Thread Starter Member

    Jun 14, 2009
    24
    0
    Would i be able to put an LED somewhere in the circuit to have it go on when it is done charging? And how fast would it charge?
     
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