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
    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?

    Senior Member

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


    Jul 17, 2007
    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.

    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.