Electric fence

Discussion in 'General Electronics Chat' started by nikkdar, Sep 26, 2009.

  1. nikkdar

    Thread Starter New Member

    Feb 28, 2009
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    Hi all, could anyone supply an electric fence pulser diagram 6 - 12volt input its for chickens or correctly foxes to protect the chickens from them.
    Thanks Nikk.
     
  2. mauro.laurenti

    Active Member

    May 8, 2009
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    In my place they put the net under the ground, blocking the fox from making an hole...

    ...by the way if you put an electric shock you would need to put a double net. The internal net should be without shock.

    If you create shock to the chicken, they will not make eggs.

    Ciao,

    Mauro
     
  3. mik3

    Senior Member

    Feb 4, 2008
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    How do you know that?
     
  4. mauro.laurenti

    Active Member

    May 8, 2009
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    when they are stressed or scarred they not make eggs.
    ...from my uncles experience...

    extending this, I'm assuming that electric shock will stress them.
    This is based to the fact that I have seen animals with scares induces by electric shock. They were dog and mouse in that case.

    Ciao,

    Mauro
     
  5. nikkdar

    Thread Starter New Member

    Feb 28, 2009
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    A friend of mine has many chickens with many eggs and an electric fence around them all. You are correct they will not lay when stressed. Don't birds feet insulate them that's why birds don't fry on electric wires.I suppose their feathers will insulate them to a degree.They seem to learn fairly fast, not as stupid as they are made out to be.
    Interesting as this is i don't suppose anyone can point me towards a simple pulser circuit.
    Thanks Nikk. Herb!!!!
     
  6. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,536
    I've never build this, though I etched the PCB. Basically I was thinking of experimenting with a totally surface mounting regular hole though components. The design is a couple of years old, I've learned a few things since I designed it.

    The PCB was meant to be printing out using M/S Paint, another experiment. U2 is a 4001 CMOS chip.

    [​IMG]

    Note: This circuit generates high voltages at potentially lethal currents. You use this design at your own risk! Basically I pulse 120VAC around 30ms, though this is adjustable. I was also planning on using a gel cell battery that recieves a constant charge from a wall wart.

    [​IMG] [​IMG]
    ................................................Layout..........................................Toner Image (will reverse when transfered)
     
    Last edited: Sep 26, 2009
  7. SgtWookie

    Expert

    Jul 17, 2007
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    1,728
    Bill,
    You can't charge a gel cell like that. You shouldn't charge a gel cell at faster than it's AH rate / 8, as it would cause excessive internal heating, bubbles in the gel, and permanent loss of battery capacity. It's much better to charge it as AHrate/20, as this causes less internal heating.

    The combination of R1, R2 and R3 you have selected provides a maximum output of around 12.7v, which is not sufficient for 12v lead-acid nor gel cell batteries. If the battery internal temperature is around 77°F, the float would be around 13.37v for a 12v battery. As the internal temperature increases, the float voltage decreases.

    Charging must be limited by current until the battery is nearly charged, and then regulated by voltage.

    Also, you need to have 0.1uF and 10uF caps on the output of the LM317 to ensure stability and prevent oscillation.
     
  8. mauro.laurenti

    Active Member

    May 8, 2009
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    ...you let the chicken learn the hard way...
    as a baby will learn that the oven must not be touched! :)


    Ciao,

    Mauro
     
  9. Wendy

    Moderator

    Mar 24, 2008
    20,765
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    The ideas about the LM317 are granted. I would also include a resistor to limit charge current, similar to what you showed a while back.

    The core idea is the battery start charged and stay charged, and is used like a capacitor to provide surge currents. When I was a kid (30+) years ago that was the core problem I kept having, circuits like this require a large rush of current, even though the average requirements are modest. This not really meant as a battery charger in the traditional sense.

    So R2 needs to be 1.1KΩ, and a 0.1µF and a 10µF cap needs added on the output of the LM317. Maybe add a 10Ω resistor to the input of the LM317 in series with the power supply along with another fuse. This unit was fundimentally going to be outside, with a wall wart inside. Anything else you can think of?
     
    Last edited: Sep 26, 2009
  10. SgtWookie

    Expert

    Jul 17, 2007
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    The current sense resistor Rs needs to go between the output of the LM317 and the junction of R1 and the load. The value of Rs sets the output impedance of the charge circuit. Zout = Rs(1 x R2/R1).
    If the battery is rated for 10Ah, the maximum charge rate would be 10Ah/8 = 1.25A, but the 20 hour rate would be 500mA.

    If you were using 120 Ohms for R1 and your Vref were 1.26v (which I've found to be fairly typical) and you wanted the float to be 13.37v (assuming a 12v battery at 77°F), R2 would need to be roughly 1153 Ohms.
    To get the right Zout, if Rs = 2.5 Ohms, Zout is roughly 26.53; 13.37v/26.53 Ohms = 504mA (roughly).

    Yes, I realize that. However, in rural areas power is less that completely reliable, and you have to figure that sooner or later there will be an outage, and the battery will need to be re-charged soon after.

    Leave out the 10 Ohm resistor on the input side of the 317. A small Rs will take care of it.

    Don't forget to add notes to your bjt 555 stuff that each timer needs a 220uF cap and an 0.1uF cap across the power pins. Old timers know about that, but our n00bs seem to keep tripping over that omission.
     
  11. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,536
    Actually, with the 12V battery as part of the power supply buss, I would think you could get rid of the large capacitances. You don't agree I take it. The small caps I could see, since we're talking about a freq response issue.
     
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