Electric fence charger using a thyristor

Discussion in 'The Projects Forum' started by m-elektro, Nov 23, 2009.

  1. m-elektro

    Thread Starter New Member

    Aug 1, 2009
    1
    0
    Hy!
    I want to make a fencer wich operated on 12V car battery but use a some thyristor to trigger a trafo (car bobine).
    I allredy have one project wich using a two NE555 and 2N3055 to drive a bobine but sometime 2n3055 go to hell .every original fencer has a thyristor to drive a trafo, but i dont have shematic for it.
    if anyone have something to trigger a thyristor with NE555 in pulses of 1 sec?
    Hlp!:confused::confused::confused::confused:
    :)
     
  2. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    Please enlighten me. What is a trafo and (car bobine)? Is it a spark coil?
     
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    From a brief Google search, I believe that you are correct.

    What he's calling a "trafo" or "car bobine" appears to be what we would call an "ignition coil" or "spark coil", or high voltage transformer.

    A thyristor (SCR, TRIAC) would not be suitable for supplying the primary current of a coil if the power supply is DC. A thyristor would turn on, but it would not turn off until the current through the device fell to zero.

    If the supply were AC, it might be accomplished; however you would also need some electronics running on DC to perform the desired 1-second timing.

    I believe the problem is being caused by a few things:
    1) A 555 timer would not be able to output sufficient current to saturate a 2N3055 transistor; thus the transistor would dissipate power as heat.
    2) Reverse-EMF from the coil's primary would destroy the transistor if there were no protection for it.
    3) A current limiting resistor is used in automotive applications to decrease heating of the switching transistors/MOSFETs. I suspect one is not being used in the current application.

    Please post a schematic diagram of your existing circuit.

    This will help a great deal in evaluating what is wrong with it, and how to correct the problem so that it will seldom, if ever, happen again.

    [eta]
    It will also be very helpful to know:
    1) What is your source of power; eg: 120VAC 60Hz, 220VAC 50Hz, 12VDC (battery), etc.

    2) If your project uses a power supply, it would be helpful to include details on it.
     
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