Modern implementation of electric fences
Subject electroshepherd and electric fences for pets for several decades is relevant to anyone who is farming. Modern implementations of electric fences offer participants of the forum Russian site http://www.fermer.ru, which result in an electric fence circuit and share the experience of its manufacture with their own hands. Materials Forum http://www.fermer.ru outlined below.
Let's start with insulators and poles for the electric fence. In general, the easiest and more convenient to use the valve (or a thick wire D> = 10mm). Hammer drove it into the ground, put the insulator, that is ready to support. But it is expensive (the columns should be put in about 10-20 meters, so it is necessary 50-100-200 columns is money).
You can make columns electric fence with their hands from the sticks of hazel and maple 2-3 cm thick - cheap, cheerful, it does not look very nice, but quite acceptable. To install these poles can be used scrap (stick a crowbar in the ground shook, he pulled out and so a dozen times in the same place. After that, a hole in the earth turns a depth of about half a meter).
Insulators electroshepherd can be made with your own hands from plastic bottles: cut off the bottom, put it on a stick, one or two turns of wire around the neck of the bottle and you're done.
The wire can be used a thickness of about one millimeter. The problem is that the cattle thin wire at first did not notice, but the problem is easy to fight, I'll tell about it later. Assume that we have 1,000 meters of the wire, and this weight would be approximately 6 kg. Option - not buy wire, take a few tires on the truck and burn, in one such tire approximately 150 meters of wire, and maybe more, wire there though and a little fragile, but the fence will go. So without spending a penny can make the fence.
It looks electric fence as follows:
With a generator for electric fence is more difficult. The generator produces high-voltage pulses, which are supplied to the fence. What should be voltage?
Pulses voltage of 10-12 kilovolts (kV) can penetrate our insulators, and the system will not work. On the other hand a low voltage of about 12 volts almost no effort. Good hammer 220, but if you take up the bare wire with a dry cotton or woolen cloth, the shock will not hit us (just do not have to check it once again). And there are cattle wool, and cattle in dry weather may not strike. Any insulator has a breakdown voltage in air is approximately equal to the voltage vacuum breakdown (3 kV per millimeter). Coat of cattle is not very thick and when you touch the wire is free to close to the skin in less than a millimeter, and at some point slip spark. So I think that generator shall be no more voltage 3 kV. But to our cattle not killed, it is necessary to limit the electric current.
Generators with the parameters that I have described above (hit hard, but do not cause harm to health) has almost every family, and many tried myself. This generator - ignition system in a car.
The simplest thing you can use as a generator of electric fence - it magneto in an internal combustion engine, I think, has a magneto, many have tried.
Take a magneto ground wire to the magneto on the hedge, but in parallel, it is desirable to put the candle. The fact that the magneto can output voltage is higher than we have no load, and the candle is limited to a value of the voltage required to breakdown the gap. So adjusting the gap on a spark, we limit the voltage that generates the magneto.
Deadly talk to humans 20-30 LAM? Where did this take? In one case, when a person is killed by 12 volts and has a man who jolted from 10 kV line and he is still alive.
In general, we need a high voltage of about 3 kV. There are two ways: use a voltage multiplier or a transformer. I used transformer. Step-up transformer is needed to 100-250 volts of 3 kV or more. The TV has a line transformer that can deliver 30-40 kV, but it's overkill. The car has an ignition coil, it is for motorists ignition coil, which is an auto for us. The fact that the ignition coil is powered in a car 12 volt - it's not a problem, experience suggests that the ignition coil can be supplied with a pulse current of a higher voltage.
Get a short high voltage pulse with a limited current can discharge the pre-charged capacitor through the primary winding of the ignition coil. Periodically charging and discharging the capacitor through the primary ignition coil, we obtain the required high-voltage pulses of us leaving the ignition coil.
Below is a diagram of a working electric fence, it is possible to simplify (a simpler version of the show later).
In the production and operation of electric fence is important to remember safety. The circuit has one serious drawback.
The scheme used transformer (ignition coil). In auto-transformers connected to the primary and secondary windings. This leads to the fact that in the circuit at high voltage and low voltage circuit common ground. Therefore, if you when you turn on the electric fence reverse phase to earth (and it is not hard to do), there will be a short circuit.
Solutions to this problem you can think of a lot. The simplest and cheapest - just between the first land and a source of electrical current to insert a resistance of 100 kOhm. In case of wrong inclusion through resistance R4 (scheme quote below) will flow current 2.2 mA and the circuit just will not work. This resistance to work the fence virtually no impact.
And now about the parameters of the scheme of electric fences (some elements are driven by a significant margin).
Diodes (VD1, VD3) - Russian rectifier diode average power КД226В, direct analogues not found, you can pick up on, indicated in the table.
Diode (VD4) - will all the high-voltage diode (from 10 kW). In general, this element is not required. Can any other, only to hold 400 volts and a current 10mlA.
Resistance - just 1 watt, ratings are given in the diagram.
Capacitors - 400V, capacitance on the scheme, preferably metallized single-layer sealed and compacted (non-electrolytic), and can be electrolytic, but do not mess with the polarity.
Shockley diode (VD2) - Russian КН102И (can be with the others, but they have a turn-on voltage is less), it can be replaced by DB3.
Thyristor (T1) - Russian КУ202Н, it can be replaced by BTX32S100, H10T15CN, 1N4202.
The coil - can be done in two cutting board "dovetail" and wind the wire on the board.
How does the scheme of electric fences (without considering the scheme R4)
Diode VD1 acts as a half-wave rectifier.
Through the resistance R1 charges the capacitor C1, which defines the "power" pulse. To increase the "strength" of impact is necessary to increase the capacity of the capacitor C1, but most do not recommend 2mkF. The voltage across the capacitor varies as U (t) = 310 * (1-exp (-t / (2 * R1 * C1))), this formula is not quite accurate, but for an understanding fit perfectly. C1 is charged to 200 volts in less than 0.1 seconds.
R2 is charged via the resistor capacitor C2 which determines the pulse repetition frequency. The voltage across the capacitor varies as U (t) = 310 * (1-exp (-t / (2 * R2 * C2))). C1 is charged to 150 volts for 0.5 seconds, at which time opens Shockley diode VD2, which opens the thyristor T1. The capacitor C1 is discharged through the thyristor on the primary winding of the transformer, capacitor C2 is discharged through the thyristor and diode VD3 to the primary coil of the transformer. The output of the transformer is formed by a high-voltage pulse. After the capacitors to discharge, closed dynistor thyristor and the process begins anew. The first graph shows blue voltage versus time for the capacitor C1, and C2 for red. The second graph voltage at the primary winding of the transformer with time.
Candle limits the voltage.
Diode VD4 (optional) is necessary because it is not unipolar pulses are generated on the output of the transformer. The fact that the wire itself constitutes a capacitor which is charged through the diode VD4. And the charge on the wire is always there.
Here is a simplified diagram of an electric fence:
The principle of operation of the electric fence
Through diodes VD1 and VD2, and resistors R1 and R4 is charging the capacitor C1. Up to two hundred volts capacitor must be charged in a time of about 2 * (R1 + R4) * C1 = 0.6sek. In R2 and R3 resistors assembled the so-called voltage divider with a ratio of 200/1. At that time, the voltage on C1 is close to 200 volts, the voltage on the control electrode of the thyristor is close to one volt. When voltage thyristor 1volt should open and the capacitor C1 is discharged through the thyristor. And then all over again.
Maybe the problem is "oak" thyristor (T1) - Russian КУ202Н, it is not given the exact parameters in the documentation (for the majority of thyristors unlocking voltage lies in the region of 0.8-1.2 volts, this is written, which is less than seven volts, and guessing here).
There is a method of manufacturing the generator for electrical fences easier. More precisely, not necessarily to do with his hands generator, generator for electrical fences sold almost ready. I bought a generator on the market for 90rub - an electrical lighter for the gas stove, powered by batteries. There is one drawback: it has rather weak, but this is easily solved by replacing the capacitor C1 larger capacity (1 uF). Candle and a high-voltage diode is also needed, as well as previous versions. I would also put a diode in front of a thyristor (as shown below), it would be less than the current guzzled. Lighter consumes about 120 LAM, the battery will run it no more days. So it is better to be powered from any trehvoltovogo power supply. In principle, the scheme can be altered by the power of 220 volts. Perhaps this generator will be short-lived, like all Chinese. I think the weak point is the high voltage transformer. The oscillator circuit for an electric fence:
On sale there thyristors, holding more than 3 kilovolt. Russian KU202N holds 400 Volt, it certainly can be, and can withstand more than once in two or three, but not 30-50 times. Yes, you can use the FA and TDKS only is there anything easier to make a mess. Intuitively, it seems safer to use a line transformer, but hardly anyone was killed ignition system. This is even more simple scheme electroshepherd:
Proposal to finalize design of the electrical fence of party forum
Actually scheme strochnike for discussion. In such a scheme, I made a small explosive machine, used for large two-stroke more powerful and less cranky converter. But the electric fence is not so fundamentally. Well, for electric fences do not have to put the Russian УН9-27 (its counterpart HRT-402), and R2 is increased to about 1 megohms. As a bonus from this transmitter can be powered fluorescent lamp and have a grazing not only fencing but also light. Possible analogue Russian КТ|-838A - 2SC1942, 2SC3026, Russian ТВС-110ЛА - old black and white TV line transformer.
Driving and picture made with their own hands are shown below.
Tips for operating an electric fence from the forum participants
1. The most important thing is to understand where her cattle being beaten, she instinctively ran forward and fixed her reflex to move forward, under the influence of the pulse. Now, even if you accidentally touch, it increases the likelihood of failure. At constant pasture with hedges, cattle and begins to feel the induction is not afraid to go beyond the bars, if not get through the wire. I notice that just feels de-energized sections and can be easily tear.
2. Last summer, bought an electric fence in Belarus. Grazed sheep - 30 goals. At first everything was fine, grief did not know, but after a while one adult sheep learned to get out of it. Especially watching her, first walking, grazing, both gorged - runs to the place where I had them run and just jumps with acceleration - all the rest of it through. It rises above the wire-useless, simply breaks with overclocking. I had to tie it to a rope in a pen. And I suffered all summer. By the way, the geese have a very good feel an electric fence, never outside did not get out. This summer I want to try sheep with cows and calves in the shepherd's mouth. I do not know, will or not.
The wire is pulled in three layers so that the lambs can not crawl underneath. Plus, between the top and middle rows of wire - split with flags to wire was noticeable. Even the geese did not pass. Sheep - not a dull thing, but on the contrary, very clever. Smarter cows - that's for sure. It beats them really far fewer cows, because the hair is not dry conductor. If the muzzle or feet touches - bounces. a sideways approach - lean against the wire and though that. I had been in trouble with the neighbors when someone just pulled the rack out of the ground, about 10 pieces in a row and just laid on the ground. So I do not understand - whether teenagers had fun, whether I wanted to hurt. The grid can be set course, but I'm afraid that someone will steal it for their own needs.
3. Bought shepherd cow calves in the past year. The first day - was a nightmare, especially calves, went ahead !! I had to accompany them along the perimeter fence, the evening began to fear, and the next day they were grazing on their own. Shepherd cost is not cheap, but the entire grazing period they walked in front of me and, of course, for me it was quieter. But these columns, if the concrete pour can and will stand. I had to buy a tube of 15 mm and have to make their own, as the factory were stuck just 15 cm when the wire is stretched -. They sag, especially in humus !!! Generator itself is not so expensive !! The basic price make these very columns, and I had to buy 20 pieces.
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