Tuesday, December 20, 2011

A Homemade Fence Charger, Energizer Circuit Explained

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The electric fence charger circuit presented here is basically a high voltage pulse generator. The super high voltage is derived from a commonly used automobile ignition coil. An astable multivibrator is used to generate the required frequency to drive the ignition coil. Another astable is used to control the pulses supplied to the fence.






If you have large agricultural fields and desperately need to protect the crops from uninvited guests like animals and possibly humans, then this electric fence charger device is just what you are looking for. Build and install it yourself.


An electric fence is an electrified high voltage barrier which produces painful shocks if physically touched or manipulated. Thus such fencing basically function as deterrents for animals as well as human intruders and stop them from crossing the restricted boundary.

The present circuit of an electric fence charger is designed and tested by me and has proved sufficiently powerful for the application. 

The circuit is able to produce voltage pulses up to 20,000 volts, needless to say about the fatality rate involved with it. However the pulses being intermittent, provides the subject with enough time to realize, recover and eject.

The generated pulse is so powerful that it can easily arc and fly-off between short distances of around a cm. so the fencing conductor needs to be separated adequately to avoid leakages through arcing and sparking. If not tackled, may drastically reduce the effectiveness of the unit.

Here the generation of high voltage is primarily carried out by an automobile ignition coil. 

The winding ratios of an ignition coil are specifically designed and intended for creating high voltage arc between a two closely spaced conductors inside the ignition chamber to initiate the ignition process in vehicles.

Basically it’s just a step-up transformer, which is able to step-up an input applied voltage at its primary winding to monstrous levels at its output or the secondary winding.

SOME POINTS OF THE CIRCUIT AND THE IGNITION COIL IS VERY DANGEROUS TO TOUCH WHEN POWERED. ESPECIALLY THE IGNITION COIL OUTPUT IS TOO LETHAL AND MAY EVEN CAUSE PARALYSIS.







Let’s diagnose the whole thing more deeply.

 Circuit Description


In the CIRCUIT DIAGRAM we see that the entire circuit is basically comprised of four stages.
A DC oscillator stage,

An intermediate 12 to 230 volts step-up stage,

The voltage collector and firing stage and
The super high voltage-booster stage.

 TR1 and TR2 are two normal step-down transformers whose secondary windings are connected through SCR2. TR2’s input primary winding may be selected as per the country specification.

However, TR1’s primary should be rated at 230 volts.

IC1 along with the associated components forms a normal astable multivibrator stage. The supply voltage to the circuit is derived from the secondary of TR2 itself.

The output from the astable is used to trigger SCR2 and the whole system, at a particular fixed intermittent rate as per the settings of P1.

During the ON periods, SCR2 connects the 12 volt AC from TR2 to the secondary of TR1 so that a 230 volt potential instantly becomes available at the other end of TR1.

This voltage is fed to the voltage-firing stage consisting of the SCR1 as the main active component along with a few diodes, resistor and the capacitor C4.


The fired voltage from SCR1 is dumped into the primary winding of the ignition coil, where it is instantly pulled to a massive 20,000 volts at its secondary winding. This voltage may be suitably terminated into the fencing.

The high voltage generated by this electric fence charger will need to be carefully applied across the whole length of the fence. 

The two poles from the ignition coil connected to the fence wiring should be kept at least 2 inches apart. 

The pillars of the fence should be ideally made of plastic or similar non conducting material, never use metal and not even wood (wood tend to absorb moisture and may give path to leakages).

Parts List

R4 = 1K, 1WATT,
R5 = 100 OHMS, 1WATT,
P1 = 27K PRESET
C4 = 105/400V PPC,
ALL DIODES ARE 1N4007,
IC = 555
TR1 = 0-12V/3Amp (120 or 230V)
TR2 = 0-12V/1Amp (120 or 230V)
BOTH THE SCRs ARE C106 OR PREFERABLY BT151,

TWO WHEELER IGNITION COIL IS SHOWN IN FLUORESCENT BLUE COLOR


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Reactions: 

46 comments:

  1. thanks for the info.its really help me in my assignment.i hope u allow me to copy all of these.hehe thank u

    ReplyDelete

  2. there are difference betwen schematic and material list. can you clear it?
    Very good apport!!!!!!!
    thanks

    ReplyDelete

  3. Can we simply use a CDI unit of any motorcycle?

    ReplyDelete
    Replies

    1. Very good suggestion , in fact you can do it, but you will have to first understand the outputs from the CDI and connect them correctly as per the above diagram.

      Regards.

      Delete

  4. Hello swagatam: i´m trying to mount the circuit; in correction, you rotate scr2. ???
    thanks.!!!

    ReplyDelete
    Replies

    1. Hi,

      Yes you are right, SCR2 is wrongly connected, just turn it round to make the connection right.

      Thanks.

      Delete

    2. Can you post a new Diagram for the wrongly connected SCR2 Circuit?

      Delete

    3. Yes I'll do it very soon.

      Delete

    4. I've corrected it, kindly check it.

      Delete

  5. I´m building circuit, but output trafo is very low; what can i do?

    thanks

    ReplyDelete
    Replies

    1. which circuit did you build? I would suggest, you build the upper circuit first....

      Delete

  6. Hello swagataM:
    I built upper circuit en work ok. I add temp (below circuit) and output TR2 is very low. ?????
    Thanks

    ReplyDelete
    Replies

    1. Hi,

      Yes, it's because we have used an SCR, please replace the SCR C100 with triac BT136.

      Thanks and Regards.

      Delete

    2. Do I replace both SCR 100?

      thanks

      Delete

    3. Only the right hand side SCR needs to be replaced with a triac.....

      Delete

  7. Hello suagatam:

    I like very much your circuit but it is highly dangerous! In eleectric fences, time pulses must be less than 10 ms; freq, 1 Hz aprox. If you review TEMP 555, Tm is greater than 10 ms. I suggest review design because it es a good aport. Please, let me know if I am wrong.

    tkanks

    ReplyDelete
    Replies

    1. Hi,

      I think you may be right, I would appreciate of you could do the necessary corrections so that I can correct the diagram accordingly.

      Regards.

      Delete

    2. Hi Anonymous;
      What IC do you think should be used in place of the 555 IC ?

      Thanks

      Delete

  8. Thanks you for your confidence. I´ll try to do it soon.

    Regards

    ReplyDelete

  9. Hi Can I make this Energizer using just a 12v battery to keep horses in. Am I correct in thinking the circuit is intended for AC at 240 so if I leave the first transformer out and put 12v battery in will it still work as using direct current without other modifications ?
    Regards Thanks

    ReplyDelete
    Replies

    1. Hi,

      If you leave out the first transformer, the second transformer would need a 12v AC for operating the energizer circuit.

      Probably it's the second circuit which will function exactly as per your requirement, you may try it.

      Regards.

      Delete

    2. Oh yes.... you may eliminate TR1, in case you employ the second circuit.

      Delete

  10. wats d use of d capacitor, the one which is in parallel with IN4007?

    ReplyDelete
    Replies

    1. for switching high voltage to the coil....

      Delete

    2. hello sir...
      this is really nice... but how we can apply this to the fencing sir..?? i mean this circuit should be attached to normal fencing??

      Delete

    3. Hello Siree,

      Since this circuit involves high voltages, requires utmost care while applying to the fences, which must be accurately laid down as per the instructions.

      Delete

  11. Hello ! I have some rodents digging new holes almost on daily basis in my home lawn. I have tried my best to fill the holes with even broken glass bits, broken brick bits but they manage to dig new holes. The holes are about 2 inch wide and go deep in the ground. I tried simple mousetrap as well but failed.

    And dogs getting the smell of the rodents also dig my lawn.

    They all have created a mess.

    I want to make an electric fencing used a 12 V power source + a motorcycle CDI unit and a motorcycle ignition coil.

    I want to put this small 2 inch high fencing along the holes that rodents have made so that while going in and out they can get electrocuted.

    Help me with circuit diagram please.

    kaps163 AT gmail DOT com

    ReplyDelete
    Replies

    1. You may build the circuit shown in the second diagram, it will work for you.

      By the way we don't want to electrocute the animals, just drive them off.

      The shown circuit is actually a motorcycle cdi unit.

      Delete

  12. Hi Swagatam
    I'm From Sri lanka.Our villages are facing life threaten problem because of elephant. in night people couldn't go out because elephants are hanging here and there. once a week a human die b'couse of elephant attack. What i really begging you give me a high voltage dc fence energizer circuit diagram to use each house . Must be low budget because our villages are very farmers.In my area we don't have ac power.We are using 12v battery power. Please give me a good solution.

    ReplyDelete
    Replies

    1. The circuit explained in this article can be used for guarding houses, however i am sure whether it will be enough for stopping an elephant's might....not sure.

      You may try it though, it uses low cost auto ignition coil and some ordinary electronic parts.

      Regards.

      Delete

  13. A simple high voltage unit can be made by cutting off the bottom inch or so of the coil.Connect negative as normal fasten coil in upright position on door post and run high voltage across the door. Knock nail into doorpost about half inch below the square iron core of the coil ,bend a strip of iron round nail and connect nail to battery positive. Let the iron strip rest on any fixed piece of metal with a wire going to the coil positive. It works thus, the positive current flows through the loose iron flap, which is resting on the metal connected to the coil positive. This energises the coil making tthe core magnetic and attracting the loose iron strip. this breaks the circuit and the loose iron strip rests on the metal connected to the coil and the circuit repeats itself. To improve it make the loose iron flap a weak spring and the system becomes portable

    ReplyDelete

  14. Dear squire,

    Please post a circuit diagram

    ReplyDelete

  15. wher did you get the capacitor C4 from ???

    ReplyDelete
    Replies

    1. C4 is an ordinary high voltage polypropylene capacitor.

      Delete

  16. Please sir can send me a book in pdf or ppt from which i could from basics to higher level about electronics . I love electronics . Plese send it to vaibhavdhiman10@gmail.com
    thankyou

    ReplyDelete
    Replies

    1. Hi, Vaibhav,

      Presently I do not have any such suitable book for the beginners, if I find one will surely inform you regarding it.

      Regards.

      Delete

  17. HI
    the circuit works great but please tell me the exact capacitor spec to be used to get the output

    ReplyDelete
    Replies

    1. Hi,

      C4 is 105/400V or 1uF/400V, metallized PP capacitor.

      0.01 is ordinary disc ceramic,

      1uF and 1000uF are ordinary electrolytic type.

      Delete

  19. swagatam,
    excellent work with the electronic diagram. I am impressed with your patients toward others that are less fortunate, with meager resources and limited knowledge. It is easy to be impatient with others if a you can't understand the context of the writer and their immediate situation. In this world of profit and money, the poor who are the planets majority really need easy, cheap solutions to their problems. can you imagine having your sister killed by WILD ELEPHANTS while peeing in a dirt hole at 2am because "rich people" wouldn't explain a simple electrical schematic?
    thank you from all of those that can't say it.

    ReplyDelete
    Replies

    1. Thanks very much, I highly appreciate your feelings!

      Delete

  20. hey, i want to make one for my field fence i have unwanted horses in and i want them out, anyway. i have no idea what your talking about as i am not a technition haha and i am totally confused but really need to build one to get the eletric flowing. out of all the thing i have looked at yours seems to be the most explained. but i have no idea what any of them things are or where to get them i have a soilder iron and soilder ready haha.
    Thankyou

    ReplyDelete
    Replies

    1. If you are so very new in the field, and confused, I wouldn't recommend you this circuit, it's strictly not for the newbies.

      Delete

  21. Can you please explain the connections to the fence wiring. You said:The two poles from the ignition coil connected to the fence wiring should be kept at least 2 inches apart.I did not get that part.

    ReplyDelete
    Replies

    1. the fence barb wires must be stretched through rigid non conductive pillars positioned close to one another in order to keep the wires tightly held.

      all the barb wires must run parallel at a distance of about 6 inches from each other (not 2 inches actually).

      The current from the above circuit must be fed to the alternate wires such that when an intruder touches any of the two barbs, the voltage gets a path through its body, and provides the required shock.

      Delete

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