A Fence charger or energizer is an equipment which is used for charging(electrifying) a fence or a boundary in order to protect the inside premise from human or animal interventions.
Since these boundaries are mostly of large fields and parks, are normally away from the main cities, and powering them through some renewable option becomes more suitable than from utility grids which may become difficult to acquire in such remote areas.
The circuit of a solar electric fence charger explained here does not depend on traditional power source for operating, rather gets it 24/7 from a self sustained solar power conversion set up.The circuit is very simple to understand.
The fence charger circuit is basically a switching circuit which involves a few diodes and a high voltage capacitor.
How the Circuits Works
The diodes are used for rectifying the AC from a small step up transformer so that it gets stored inside the high voltage capacitor.
When this voltage reaches a particular threshold, the SCR fires and discharges the entire stored voltage inside the capacitor.
The above discharging of the capacitor is done or rather dumped inside the primary section of an automobile ignition coil.
The sudden dumping of the above high voltage inside the ignition coils primary, steps up the surge into several thousands of volts into the secondary winding of the ignition coil.
This stepped up voltage is used for energizing the fences or the boundaries appropriately.
However the above operations requires an AC input at the levels of around 100 to 220volts.
This voltage is generated by suitably processing the input DC from a solar panel set up.
The voltage from the solar panel is first controlled to a suitable level and then it's used for operating a triggering circuit.
The triggering circuit consists of a IC 555 oscillator which switches the voltage obtained from the solar panel controller into the transformers input, so that the output from the transformer generates the required 220V AC for powering the ignition circuit.
The solar panel output also charges a small 12V/7AH battery so that the power can be used after dusk, when sun energy is not available.
Parts List
- 10k, 100k, 1k 1/4 watt 5% = 1 each
- 470 ohms, 100 ohms 1/2 watt 5% = 1 each
- preset 100k = 1no
- Capacitor 1uF/25V, 100uF/25V electrolytic - 1 each
- Capacitpr 0.01uF disc ceramic = 1 no
- Capacitor 105/400V PPC = 1no, near the SCR
Semiconductors
- 1N4007 = 4 nos,
- IC 555 = 1no
- LED red 5mm = 1no
- Transistor TIP122 = 1no
- SCR BT151 = 1no
- Transformer = 0-12V/220V 1 amp
- Ignition Coil from 2-wheeler or 3-wheeler
The above circuit can be powered through the following solar panel current controlled battery charger circuit:
For complete explanation of the circuit please refer this solar voltage regulator circuit.
Parts List
- R1 = 120 ohms
- P1 = 10k pot (not 2k)
- R4 = replace with link
- R3 = 0.6 ohm 1 watt
- Transistor BC547 = 1no
- IC LM338 = 1no
- Diode 1N5408 = 1no
- Solar Panel = 16 V / 2 amp
- Battery 12 V 7 Ah
Fence Charger using a Stand-alone Inverter
Video clip showing the working details of the fence charger circuit. The video basically highlights the strength of the sparks generated by the CDI coil and how effectively this can be used when integrated with a farm fence.
Jean-Michel Farley says
Hey Swagatan,
I’m planning to use the first circuit to protect a hive from bears.
– The output cap is a ”PPC”, what is it? Could an electrolytic capacitor be used instead?
– I’ve read that you need about 1 joule to deter bear. Using the formula W=0.5 CVsquare and 220V, I get the need for a 41 uF capacitor. Is it still safe for human beings? It is too much in general in your opinion? It seems like a big upgrade from the 1uF capacitor.
– Should I increase the value of the output cap, do I need to increase the watt of the 100 and 470 ohm resistor?
– From what I have read about IC555 and calculated, this circuit give about 4,8 pulses per second, am I right? I need to increase the value of the resistors and cap at the right of the IC to diminish the pulse frequency?
Thanks for your help.
Swagatam says
Hi Jean,
The output cap should be specifically a PPC or MKT. You can search online with the phrase PPC capacitor, you will be able to get an exact idea regarding its type.
I am not sure about how much joule would be required, but the output from this generator is around 27 kV enough to kill a human being within minutes, so it should be enough to scare away any wild beast, even an elephant, according to me.
So no changes would be required in the existing circuit.
In the 555 circuit you can adjust the 100K pot to get the required ON/OFF timing, yes it will produce 4.8 Hz with the existing parts, which can be reduced by increasing the value of the 1uF capacitor, which can be an electrolytic capacitor
Jean-Michel Farley says
Thanks for your fast answer Swagatam.
Let’s say I’d want to energize more than a 100m of fence, what change would I need to do to the circuit?
Swagatam says
I think for 100 meter coverage you can can build 10 such units and install them after every 10 meters. This will ensure uniform voltage range across the entire 100 meter area. Using a single powerful unit may not be good, since the voltage level might not be uniform across the full 100 meter distance.
PAUL says
You say the ignition coil is from a two or three wheeler. Does this mean that a normal 4wheel car ignition coil cannot/should not be used?
Swagatam says
All ignition coils will work, but 2 wheeler coils are cheaper and have modest amount of current which may be suitable for fence charger application
Daniel says
Thank you!!
Jonathan Zapadenko says
Where can I get the circuit board to make the fence charger??
Swagatam says
Sorry PCB will need to be made to order
aguma alvin says
hello mr Swagatam. thank you for the work youre doing. i request you to help me with the list of components used in making the solar electric fence energizer
Swagatam says
Hello aguma, I have updated the parts list in the article
Tracer says
Hello Swagatam,
Thank you for sharing.
Do you possibly have a circuit to test the output voltage of the coil to the fence, preferably a circuit that uses high bright LED’s?
Swagatam says
Hello Tracer,
an LED will not give any useful information. Instead you can put a resistive divider using a series 1M/10K resistor, and connect a DC voltmeter across the 10K. The result will be 100 times smaller than the output voltage, and therefore can be multiplied with 100
Tracer says
Hi Swagatam,
Thank you for your reply.
Your suggestion to use a resistive divider with 1Mohm resistors sounds promising, if you have the time would you care show how you would go about calculating a divider to measure the output voltage, (20KV), of your fence charger for example? I am also a little confused how a voltmeter or digital multimeter can measure the voltage when the maximum scale is 1000V DC.
Your assistance would be appreciated
Swagatam says
Hi Tracer, The formula is:
Vout = Vin (R2 / R1 + R2)
Where is Vout is the meter voltage reading
Vin is the required high voltage value.
R1 is the high resistance value which can be 1M
R2 is the low resistance value which can be 10K.
R1 must be at the + side of the high voltage supply, R2 on the – side.
Meter should be connected across R2
Meter scale can be any lower DC range
Tracer says
Hi Swagatam,
Thank you for the information you have provided, however I really don’t really understand what you are trying to say to help me find a solution. As I am dealing with High voltages I will keep on searching until I can find a safe solution to prevent damage to my test equipment and myself. I do appreciate your attempt to help
Balram Singh says
I wholeheartily thank you that you are doing a great job.
I have a problem that I want secure 2km agriculture farm but this circuit cover only 100 meter.
What machine parts will I change that cover such a ( 2km ) large area?
Swagatam says
You are most welcome!,
for increasing the range, I think you only have to upgrade the ignition coil specs…you can try a car ignition coil instead of the shown motorcycle coil
Sidhesh dessai says
Hi sir your site is very good n I already used many circuit that I used in my farm n now I’m goin for this bcos after Diwali we are going to grow chilly so I need to fence it, it is 4 Acer of land .
1st . Is One circuit is sufficient for fencing 4 acre and what guage wire I have to use ???
2nd what is the voltage of bt151 and tip 122 , 1uf capacitor voltage
Thanks
Swagatam says
Thank you Sidhesh, I am glad you are enjoying my circuits,
Regarding the distance, I am not sure how much one ignition coil would be able to handle, you will have to check and verify this through a practical testing.
BT151 is rated at over 300V, TIP122C at 100V, the IC 555 1uF capacitor should be 25V, the one attached with the SCR should be 1uF/400V PPC
Sidhesh dessai says
Thanks sir, how to add siren to it and day night on off ,
Swagatam says
Sidhesh, for a day night switching you may have to use an external circuit and configure it with the fence charger, you can select one of the designs explained in this article:
https://www.homemade-circuits.com/2012/01/how-to-make-light-activated-day-night.html
for siren you might have to incorporate a vibration detector for detecting animal presence…it can be difficult to attach it with the fence charger and make it work…
Sidhesh dessai says
I’ve used capacitor at scr 105/400v and base resistor for transistor tip122 is 180 ohms , when I checked input volt for transformar I’m getting 9.5 volt and out 11volt and transform is getting hot
Swagatam says
it could be because your IC 555 is not oscillating or TIP 122 is faulty, or TIP not connected correctly
Sidhesh dessai says
Hi sir I have done that circuit on PCB
But I’m not getting sparks , I have used normal transformer, input 230v n out put 12v , 300 ma when I connected this I get output 11volt only n no sparks at ignition coil n transform er is getting hot n even tip122
Swagatam says
Hi Sidhesh, make sure the IC 555 is oscillating, to confirm replace the 1uF capacitor with 10uF or higher, check whether the red LED is flashing or not, it should flash rapidly.
The output of the trafo must generate pulsating 220V in response to this oscillations, also make sure you have connected the TIP122 correctly, and it is not faulty…replace the 100 ohm at TIP122 base with a 10K
Sidhesh dessai says
Thank you very much sir , Ur great ,
Sir here instead of 2n3055 u mentioned tip31c is it same or different? Cos I have 2n3055
Swagatam says
You are welcome Sidhesh, you can use 2N3055 also, no problem with that… since the current is low for this circuit I preferred using smaller transistors like TIP31,,,,
Sidhesh dessai says
Hi sir thanks for reply, I already check tip is connected prprly , facing tip towards us first pin is base( is comin from pin 3 of 555 through 10k resistor ) ,2nd pin collector ( goin to transform 12v side ) , 3rd pin is emmitir ( is connected to output of transformar 230v side , which is negative to CDI coil) tip 122 is getting very hot , pulsing rate is ok since very fast led is blinking , I’m getting output to 12v only from transformar ,
Pls help me sir , if you have any other circuit which give even 10kv also it’s ok
Swagatam says
Sidhesh, remove everything from the transformer secondary and first confirm whether the transformer is generating 220V or not.
connect a 1N4007 diode across collector/emitter of tip122, anode to emitter, cathode to collector, this is supposed to be already present internally for the transistor but just for extra safety I am recommending this.
now connect a 10 watt bulb across the 220V side of the transformer and check whether it is glowing or not…
the supply voltage should be around 12V 2 amp to the 555 circuit.
add a heatsink to TIP122 to keep it cool.
the concept is too simple, if the 12V primary of the transformer is pulsated with a 12V Dc, the secondary 220V side will accordingly pulsate and generate 220V DC, through magnetic induction.
Swagatam says
this circuit was designed by me for auto-rickshaws and has been thoroughly tested, it worked immediately for me…
Sidhesh dessai says
Hi sir I have done as u said but nothing change , but when I’m disconnect transformar tip is not getting heated up it remain cool I think there might be ptblom with the transform r ,
On transfrmr it is written as
07337100
I/p: ac 240v 50hz
I/p : 12v 300ma
Eng EI-350343
Or should I change the tranform r
Swagatam says
Sidhesh, you are having difficulty with the IC 555 stage, you can try the following circuit, eliminate the entire IC 555 stage and replace it with this circuit. Don’t use TIP122 use any non-Darlington power transistor NPN
https://www.homemade-circuits.com/2012/02/how-to-make-simplest-inverter-circuit.html
Sidhesh dessai says
Sorry it’s O/p 12v 300ma
Swagatam says
I hope you have connected the 12V side with the TIP?? if yes then it should have worked
Sidhesh dessai says
Or is the differenct step up transformation
Or can I try with other invertor circuit of 45w output by giving input from the same circuit of urs only in place of transformar and rest as it is
Sidhesh dessai says
Hi sir , I have completed the simple invertor circuit n it’s working , I have connected 10watt bulb n it’s glowing , it’s working fine , but my main concern is for fencing , pls tell now what should I do next
Swagatam says
Hi Sidhesh, you can now build the CDI stage and configure it with the output of the inverter, for pulsing the SCR stage you will need a separate IC 555 astable circuit whose pin#3 will need to be configured with the SCr gate via a 1K resistor, and make sure to connect all the grounds together, you must connect the CdI ground, IC 555 power supply ground together, thi power supply can also be used for powering the inverter. If possible I’ll draw the design and update in the article…
Sidhesh dessai says
Hi sir it will be great if you could explain with the daigram , (now don’t have to use tip 122 ?)
Last part of scr , capacitor , n 100ohm resistor will remain same or change ???
N what if i connect output of if 555 to the input of invertor circuit
Swagatam says
Sidhesh, the IC 555 will be required only to trigger the SCR, the inverter circuit can work independently, and will not require the IC 555 assistance…TIP122 will also be not required now.
I’ll try to update the design soon…
Swagatam says
…I have updated the diagram, you can check it out.
deep prajapati says
20,000 v is dangerous for human. So, what should be the output voltage, ehich will not affect human and can be use as fencing for animals.?
Swagatam says
In the above circuits, if you use a DC source with lower current then the 2kv will be not dangerous, it will produce a nasty shock but won't kill anybody…
That said, it's responsibility to make sure that the calculations are done correctly…
Swagatam says
use 12V 2 amp as the input, this will make the 2kv very weak in current and not so harmful.. however it's your responsibility to check the results appropriately
Unknown says
20,000 v is dangerous for human. So, what should be the output voltage, ehich will not affect human and can be use as fencing for animals.?
Swagatam says
2kv can be dangerous to animals and humans only if it's accompanied with some higher current.
In the above circuits, if you use a DC source with lower current then the 2kv will be not so dangerous, it will produce a nasty shock but won't kill anybody…
That said, it's responsibility to make sure that the calculations are done correctly…
priya sai says
Would u give me the information about energiser used in this project sir..if posibl will u provide
Swagatam says
it is a motorcycle CDI ignition coil
ballo says
Hi. Is there any way to electrify a fence with a 12v source using a common ground?
I often want to park in bear country and in some areas they regularly open vehicles like tin foil wrapped burritos causing hundreds of thousands of dollars in damage annually. To use this circuit I would have to disconnect the battery's negative terminal which is time consuming and a pain in the ass.
The van wouldn't shock anyone (or any animal) until the paint was scraped off, so I would have no qualms about using a high watt circuit to deter bears in the process of destroying my vehicle.
Swagatam says
Hi, you can use the circuit which is explained in the above article.
It's a common ground circuit but for electrifying the van body a separate battery will need to be used, or if the existing battery is used then its negative wire will need to be first disconnected from the van chassis, and then electrified through the high tension cable
bhavesh makvana says
Sir your mo,nomber
vikas loh says
If we use resistor as current sensor than defenetly we have to use in series.so current pass through this resistance.but problem is current is not passing through resistor because current is passed through air by spark beetween two terminal of resistance.so resistance is not comes in picture.to overcome this problem i make three 100ohm 1watt resistance in series and put relay parallel across resistance.and i sucsess that relay is operating but on time is not more.and also spark is reduce so it is not used in large area.
Swagatam says
the current limiting resistor should be used on the DC side tat is in series with the battery positive not on the high voltage side, and I am not sure to which circuit you are referring to??
vikas loh says
But sir at higher voltage resistor is bypaas using spark and if we connect bc 547 at parrallel to the resistor then gap beetween two pin is small then spark gap so it is spark beetween two pin and its burnout.
Swagatam says
I could not understand your question.
vikas loh says
The spark gap beetween fence and earth is more than 1cm.but resistor size is small so there is spark beetween two terminal of resistance.if we use 1 watt resistance than it internally burnt because of high voltage.means it internally puncture.
vikas loh says
We make sence circuit only using ct coil used in elcb.by using op-amp like 741 or lm358
Swagatam says
which resistor are you referring to? without seeing the schematic I won't be able to suggest….
Jargo says
Hello Sir,
is there a way to easily monitor if the fence is working correctly (let's say I have multiple fences at home and have to check these daily) ?
1) fence is not broken (some kind of DC sensor at the end of fence?)
2) fence is somehow connected to ground (grass, bushes)
Could You provide a PCB or any help would be appreciated…
Swagatam says
Hello Jargo, you can employ current sensing resistors with each fence charger module to sense if any of the output is shorted, but sensing a broken fence can be a bit complicated and might involve a too many connections across the whole system.
current sensing circuit can be implemented using the following explained method:
https://www.homemade-circuits.com/2014/06/simple-current-sensor-circuit-modules.html
Jargo says
Thanks
umar says
sir, is the combination of tip 122, transformer , and 555 , making a fly-back converter?
Swagatam says
yes it is suitable.
umar says
is the polarity of transformer tr2 is same or opposite?
Swagatam says
it will be the same, low voltage side towrads the transistors and the high voltage side towards the output
umar says
sir, i meant what's the polarity according to dot convention? whether dots are on same side or on opposite sides?
Swagatam says
No polarity is there for this configuration, because the output is not linked through any kind of feedback circuit to the primary, therefore the two winding sides can be wired anyway round.
umar says
Hi sir,
1) is output of 555 timer used to apply gate pulse to SCR?
2) why have you connected output of 555 to transformer?
3) can we use tl 494 instead of 555 timer?
Swagatam says
Hi Umar, the CDI coil requires at least around 100 to 200V to produce the specified 20,000 volts, that's why the transformer is used for stepping up the 12V to this level.
TL494 can be used instead of IC 555
umar says
what changes we have to do for lower output say 10KV.?
P.S. thank you for quick reply…
Swagatam says
use 6V DC supply input
umar says
1)sir what is current rating of transformer tr2?
2)what is the rating of 100, 470 ohm connected to scr, and 100 ohm connected to tip 122?
Swagatam says
TR2 can be any small transformer such as a 0-12V/500mA/220V or a 0-12V/1amp/220V.
SCR resistors can be 1/2watt rated
The TIP122 base resistor should be above 1K, @ 1/4 watt………100 ohm is incorrect.
Umar says
Sir what is the function of tip122?
Swagatam says
to switch the transformer at the 555 frequency
Umar says
Sir, which is the primary side of induction coil? Is it the one with which the capacitor is connected or the one with which cathode of scr is connected?
And my second question is whether 555 is also controlling the scr?
Swagatam says
Umar, the capacitor side is the primary of the CDI coil.
Swagatam says
555 is controlling the CDI coil by switching TIP122, TR2, and the SCR, in a sequence…
umar says
thank you sir…
Unknown says
Is transformer tr2 a pulse transformer or simple transformer??
Swagatam says
it's an ordinary iron core transformer
avinaash jadhao says
swagatam will u arrange the solar fence tested circuit pcb
Swagatam says
would be difficult due to lack of time…
Jeffky says
When I apply power to the circuit the tip122 locks on and just buzzes I know if I leave it powered it will burn the tip122 out what could be the cause I have double triple checked the work and cannot find the problem. any suggestions would be greatly appreciated.
Swagatam says
that's not possible, if the IC555 works correctly, it's ought to oscillate the TIP122 and the transformer accordingly at the set frequency.
Increase the base resistor of the TIP1222 to 10K and the check the response.
if the trafo is an iron core type, then make sure the frequency does not exceed 100 to 200Hz…I think might be crucial to keep the TIP122 and the trfao cool
Jeffky says
Does the 12 v Battery used to power the fencer circuit have to be 7AH or will any 12 v battery work? will a car battery damage anything?
Swagatam says
the AH of the battery value can be anything, it won't affect the circuit as long as the voltage is within 15V
Jeffky says
In the schematic P1 calls for a 1M potentiometer. later it is referred to as a 27K preset. Did you change it to a resistor?
Swagatam says
I don't remember actually, but that may be possible, I might have changed the 27k to a 1M… because a 27K preset will generate a much higher range of frequency than the 1M preset which might not be suitable for the associated iron core transformer.
Suhas Labade says
Hi Swagtam this is Suhas. Your circuit looks good.
Currently Im building this but dont know how to check output high voltage and current ??? Please suggest.
Also send your you-tube video link for this project.Thanks.
Swagatam says
Hi Suhas, if you are asking regarding the solar panel measurements, it may simply done by connecting your multimter (in DC V range) prods directly across the solar panel terminals under peak sunshine, this will show you the voltage specs (open circuit voltage) of the panel, for measuring current you need to follow the same procedure again, but by keeping the meter in the DC ampere range…the reading will show you the amp spec of the panel (short circuit current)
I'll wait for the video and pics if possible…thanks!
vikas loh says
hello sir
thanks for putting circuit.i am student of engineering and my project is solar fence guard.
in first stage i use step up transformer 12v/230v and charge capacitor.in next stage i discharge capacitor in output transformer.required output transformer is 230/10 kv but i dont know current rating of 230/10kv transformer.please suggest me the current rating of 230/10kv transformer.and what is its frequency.
Swagatam says
hello vikas,
divide 10kv with the secondary voltage of the transformer
Swagatam says
frequency will depend on the oscillating frequency that you may be using to drive the trafos.
samaj says
Hy i have used bc 547 and when ckt start uts burn any idea also still i have not connected the ugnitiin coil in this
Swagatam says
BC547 has no chance of burning, something may be not correct in your circuit.
Kalpesh Dafda says
thank u swagatam bhai ,
but i m facing 1 more problem that i can't get ic LM338 and scr BT151 so can u suggest me any other equivalent ic & scr … so i can get it…!
Swagatam says
Hi Kalpesh, I am afraid there's no other reliable alternative for these two devices, because the specifications of these parts are unique and ideally suited to the proposed application, so I won't recommend any other equivalent because they could burn and get damaged overtime
Kalpesh Dafda says
and in second ckt… battery charger ckt what is the value of R1, R2(p1),R3,R4 .
THOUGH SOME OF THEM U HAVE PROVIDED. and transistor is also BT151 in second ckt…?
Swagatam says
please click the diagram to enlarge.
R4 is not required, could be removed.
R3 = 0.6 x 10/battery AH
Swagatam says
BT151 is for SCR1, the transistor in the charger circuit is BC547
Kalpesh Dafda says
btw i m working on ur ckt diagram …. it's really good.
Kalpesh Dafda says
hello… swagatam.
in ckt what is the value of capacitor just below the scr 1.
and value of capacor at pin 5 in IC 555 is .01 uf…?
Swagatam says
hello kalpesh,
the value of the capacitor is 1uF/400V or 105/400V
pin5 cap is = 0.01uF or 103 ceramic disc
koodles says
Great post. What is the output pulse waveform? is it a square wave?
Swagatam says
Thanks, I am not sure about the waveform, so can't say.
kasun says
sir howmany kilometers can use this circuit.
Swagatam says
with iron wire not more than 100 meters.
harsh deep says
what are the components for the charge controller circuit given above?
Swagatam says
transistor is BC547, rest is given in the diagram
Kalpesh Dafda says
hello swagatam… here u have used TIP122 instade of BC547 transistor…… which is correct..?
Swagatam says
yes it's possible by adjusting the 22K resistor, make the 22k resistor variable, this will allow you to select any desired pulse timing.