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need help for developing an electric fencing for my farm

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by Hrishikesh, Feb 11, 2005.

  1. chemelec

    chemelec Well-Known Member

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    This Electric Fence circuit on my website works very good.
    The Coil is a 12volt car coil and it has an Adjustable off time.

    http://www3.telus.net/chemelec/Projects/Fencer/Fencer.htm

    PC Board and parts are available from me, If Needed.
    But I Don't supply the car coil.

    Take care...Gary
     
  2. danamin

    danamin New Member

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    bryan1

    can u give a spec T2 for the electric fence circuit
     
  3. Boncuk

    Boncuk New Member

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    Ignition coils have three connections only. The primary and secondary windings use common ground.


    Boncuk
     
  4. dave

    Dave New Member

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  5. Boncuk

    Boncuk New Member

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    The circuit I posted uses PWM to control the output power of the ignition coil. The switch does not control frequency but pulse width. Frequency (1.5Hz) is controlled by R4, R5 and C4. For a higher frequency (pulse repetition frequency) R5 might be shorted or omitted.

    Output pulse duration can be varied in three steps: 16.5, 24 and 32ms, hence controlling the strength of the magetic field in the ignition coil resulting in different high voltages with engery levels of 250, 400 and 450mJ.

    Boncuk
     
    Last edited: Apr 5, 2009
  6. chemelec

    chemelec Well-Known Member

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    Actually Most have 4 Connections.

    12 Volts
    Distributor
    High Voltage Out
    and the Case is Ground to car body.
     
  7. Boncuk

    Boncuk New Member

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    May be they're made different in the USA and Canada. This is the setup of a European ignition coil.

    Please not that primary and secondary windings are connected internally for ground. The cases of those ignition coils are not connected anywhere.


    Boncuk
     

    Attached Files:

    Last edited: Apr 6, 2009
  8. tcmtech

    tcmtech Well-Known Member Most Helpful Member

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    We had one of those old style weed burner electric fencers when I was growing up.
    It did not use a induction coil. It used a step up transformer and just put about 1500 volts AC on the fence! 5 seconds On 5 seconds off.
    I could take the pulse fencers but not that one!
     
  9. danamin

    danamin New Member

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    Fence circuit

    How to check the electric fencing either it is opperate or not without use voltmeter??

    How to calculate relationship between the kV and the fencing lenght. What the maximum effective lenght???
     
  10. Boncuk

    Boncuk New Member

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    Hi danamin,

    the easiest and cheapest way to check if high voltage is generated is a piece of isolated wire wound in several turns (4 to 6) around the HV-cable and connected to a neon-lamp (the same type which is used as signal lamp in rice cookers or other household appliances). Don't disconnect or omit the current limiting resistor (neon-lamps generally operate at 50VAC)

    There is no current flow as long as nothing is being zapped, hence there is no voltage drop. So the wire length is of minor importance.

    Electric fences are mandatory close to highways (Autobahn) in Germany to avoid cattle endangering road traffic. For a fence of a total length of 4km there is only one HV-generating circuit necessary. Normall the cirucuit feeds HV into two sides of a rectangle parallel.

    Please refer to the sketch.

    For a quick check you might also "P" on the fence. :)

    Boncuk
     
    Last edited: Apr 6, 2009
  11. chemelec

    chemelec Well-Known Member

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    Is the Case NOt Bolted to the Car?
    If so, That makes a ground connection.
     
  12. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Of course it is, and you quite correct that there are actually four connections.
     
  13. danamin

    danamin New Member

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    Thanks boncuk for the info.

    Can anybody give the specifiction of any 20kv to 50kv ignition coil.

    I already use JEP-800 12v ignition coil but the output KV not very good.

    TQ
     
    Last edited: May 10, 2009
  14. xiptron

    xiptron New Member

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    I haven't read all the posts on here but here is some information and a true story that may interest.

    I worked for an industrial electronics company in the 1960's that developed an "unshortable" fence controller. The secret to it was a very low source impedance, something in the order of a fraction of an ohm. This in-itelf meant that it was virtually "shorted-out" already (if you can get your head around that) and that putting anything else across the line would had virtually no-effect on performance. The output spike was in the order of 5kV, at around 100 amps per pulse, but the duration of the pulse was extremely short, in the order of microseconds, so as not to be lethal to humans. Any grass that came across the line was instantly vaporised! It could feed 100km's wire without appreciable loss at the far end. It found wide use where it was too expensive to install conventional fencing on large outback farms.

    I know it wasn't lethal (and yes, it was legally compliant) as I took a "dare" from my boss (the designer) to actually take some pulses from it to see how it felt! I hesitated at first but when baited with an offer of $10 per pulse (a lot of money in those days), I eagerly took up the dare! I sat at a big table with the alligator clamps neatly laid out before me in two parallel rows. Grabbing them impulsively (pun intended), it seemed to take an eternity for the first pulse to arrive, as did the next one and finally the one after that. Although they were actually one second apart, it seemed more like ten seconds between each pulse - time definately did slow down. The shocks were like being hit in the chest by a train at 100kms/hr! The "slams" were massive and deeply felt, but being only 16 years old at the time I was able to withstand the energy and not have my heart stop, but my forearms were sore for days afterward. I wouldn't recommend anything as powerful as this really (we were all a bit silly in the 1960's), and suggest you seek out a ready-made and authority-approved unit in your area to avoid the possibilty of risk of injury to yourself or other persons.
     
  15. Snehal Gawande

    Snehal Gawande New Member

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    Hello sir, can i use transformer for this fencer circuit,if yes can u tell me the no. of turns for primary and secondary.If no can i use ignition coil.
     
  16. chemelec

    chemelec Well-Known Member

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    Last edited: Sep 26, 2015
  17. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    Hi,
    This fence works OK, uses an old 12V vehicle ignition coil and ballast resistor.
    E
     

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  18. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    chemelec
    Your links are broken,
    Eric
     
  19. chemelec

    chemelec Well-Known Member

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  20. chemelec

    chemelec Well-Known Member

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    It is Now CORRECTED.
     
  21. chemelec

    chemelec Well-Known Member

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    Relays are not very good for driving car coils.
    The Relay contacts get Pitted very easily over time.
    A Direct Mosfet Drive is Better.

    Also there should be an Off Time (DEAD TIME) between Pulses on Electric Fences to prevent a person or animal from getting STUCK to the wire.
     
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