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Electric Fences are designed to create an electrical circuit when touched by person (or animal). The circuit proposed in this article releases 10kV electrical pulses to the fence-line and monitor the line status. This entire system is design to drive using 25V (5A) single-rail DC power source (using 5A power supply unit or pair of 12.6V Lead Acid batteries) . Main controller of this system is Microchip PIC12F675 – 8bit microcontroller. All the line monitoring, pulse generation and alarm system controlling is performed by this microcontroller.
Citation preview
‐ 1 ‐
DILSHAN R JAYAKODY ([email protected])
Colombo, Sri Lanka
WARNING This article deals with and involves subject matter and the use of materials and substances that may be hazardous to health and life. Do not attempt to implement or use the information contained herein unless you are experienced and skilled with respect to such subject matter, materials and substances. Neither the publisher nor the author makes any representations as for the completeness or the accuracy of the information contained herein and disclaim any liability for damages or injuries, whether caused by arising from the lack of completeness, inaccuracies of the information, misinterpretation of the directions, misapplication of the information or otherwise.
All the software and firmware programs are distribute under the terms of
All the schematics, PCB designs and other documents are distribute under the terms of
This work is licensed under the Creative Commons Attribution‐ShareAlike 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by‐sa/3.0/ or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA.
Electric Fences are designed to create an electrical circuit when
touched by person (or animal). The circuit proposed in this article
releases 10kV electrical pulses to the fence‐line and monitor the line
status. This entire system is design to drive using 25V (5A) single‐rail
DC power source (using 5A power supply unit or pair of 12.6V Lead‐
Acid batteries) .
Main controller of this system is Microchip PIC12F675 – 8bit
microcontroller. All the line monitoring, pulse generation and alarm
system controlling is performed by this microcontroller.
Some of the notable features of this project are,
Support for wide range of operating voltage (15V – 25V DC)
Built‐in audible alarm system
230V peripheral interface section (followed by the audible alarm system)
Progress indicators
Line feedback and alarm status indicators
Contactless line monitoring system
Support for wide range of step‐up transformers (up to maximum of 10kV)
Compact controller PCB (10cm × 10cm)
‐ 2 ‐
Progress indicators and feedback indicator
DC Power supply input terminals
Connectors to the step‐up transformer
230V peripheral interface terminals
Alarm reset switch Probe limit Setup control Alarm status indicator
Alarm audio output level controller
Speaker connector
GND (test) terminal
Probe terminal
Test Point B
Test Point A
Fig. 1.1 - Controls and terminals of Electric Fence Controller PCB
System Controls and Terminals
As reference to Fig. 1.1, here are the list of controls
and terminal descriptions of Electric Fence Controller
PCB,
Progress indicators and feedback indicators:
Progress indicator is used to display the active
time of the electric fence line(s). This indicator
starts when the fence line(s) get electrify.
DC Power supply input terminals: Attach 15 ‐
25V DC (5A) power source to this terminal. (24V
is recommended)
Step‐up transformer connectors: Connect step‐
up transformer’s primary winding to these
terminals. (refer the TRANS1 and TRANS2
terminals of fig. 1.2)
230V Peripheral interface terminals: Connect the
230V (or less) peripheral to these terminals. This
line got activated when the alarm system get
triggered.
Alarm reset switch: Press this push button to
reset the entire alarm system. (including audible
alarm and peripheral interface terminals)
Alarm status indicator: Indicator to show the
alarm status.
Probe limit setup control: Use this variable
resistor to control the triggering limit of the
probe sensor.
Alarm audio output level controller: Use this
potentiometer to control the audio output level
(volume) of the alarm.
Speaker Connector: Attach 4Ω or 8Ω (1W)
speaker to this terminal.
Fig. 1.2 - Transformer and fence line connectivity
‐ 3 ‐
Probe terminal: Attach 4cm ‐ 8cm 13 S.W.G ‐ 12
S.W.G copper wire to this terminal. Do not
connect the probe wire to the high voltage fence
line(s). When installing the probe wire try to
install it with minimum length as possible. If the
probe attachment is too noisy, increase the value
of the R12 variable resistor. Some recommended
probe design is illustrated in fig. 1.3.
System construction and installation
Attached PCB design of “Electric Fence” system use
standard through‐hole components and SMD
components. When soldering the PCB it is highly
recommended to place all the wire‐links (jumpers)
first. Most of the resistors and transistors are in SMD
packaging. It is recommended to solder all these SMD
parts at the final stages of soldering.
When installing the heat‐sink place suitable insulators
to Q1 (TIP122), IC6(7805TV) and IC7(7812TV). Q3 and
Q2 (IRFZ44) can be directly connected to the heat‐
sink.
When installing the transformer connect one of it’s
output terminal to ground (neutral) and remaining
pin (live) to the fence wire(s). Recommended
materials for this earth electrode(s) are copper or
galvanized steel. This earth electrode should drive at
least 1.5m into the ground. At the prototyping stages
we test this system successfully with 100m long
galvanized fence wire.
High voltage safety
Most of the parts of this project contains high
voltage. AC or DC, more than 500V is consider as high
voltage. There fore, experimenters must take extra
precautions to avoid painful shocks and possible
electrocution. Here are some points which user/
designer must consider while implementing, installing
and testing this system,
Install several “High Voltage” labels in HV wires,
transformer, etc. Keep children, pets, and
curiosity seekers away from the apparatus.
Cover all bare leads, wires, connection terminals,
and possible points of contact with suitable
insulator.
Use neon lamps to check the high voltage lines.
Do not connect multimeters, oscilloscopes and
other precision test instruments to the high
voltage lines.
Always pull the plug of power supply unit when
working on a high voltage circuit unless you must
test it.
Work in a dry location. Locate your apparatus
away from appliances, metal doors and windows
sinks, water‐pipes, etc. All the above items can
become a deadly ground if your body comes
between them and high voltage.
Fence wire
Probe wire (J3)
Wire loop
Fig. 1.3 - Probe attachment to the fence wire (not to the scale)
Fig. 1.4 - Electric Fence controller with transformer
‐ 4 ‐
System calibration and testing
Majority of the components in this project are fixed
values and user need to calibrate only the few
controllers.
Use R12 variable resistor to control the probe
triggering limit. If your sensor probe is too noisy
increase the value of R12 variable resistor to 100kΩ
or 200kΩ.
To calibrate the transformer oscillation frequency
change the values of C2 and C3 capacitors. Core
oscillation frequency of this system can be monitor
through the Test Point A (TP1).
Use Test Point B (TP2) to monitor the primary
oscillation of the audible alarm.
When taking the voltage measurements (of the
control board), it is highly advisable to remove step‐
up transformer from the system. Sometimes back
E.M.F of the high voltage transformer may
permanently damage your sensitive testing
instruments.
After soldering the control board it is highly
recommended to test supply voltages to IC1, IC2, IC3,
IC4 and IC5. Expected supply voltages to those ICs are
listed in table 1.1. When taking these supply voltages
disconnect the step‐up transformer from the main
board. If all the voltage readings are correct attach
IC1, IC2, IC3, IC4 and IC5 to the IC sockets and power
on the system with step‐up transformer and probe.
Using Hi voltage voltmeter check voltages of the
fence lines.
Fence wiring system
Electric fence wires can be arrange into two designs.
1. Single electrified wire
2. Using multiple electrified wires
Both these methods had special applications,
advantages and disadvantages. Single electrified
wiring is suitable for animals. This wiring is not
suitable for vermin control. Multiple electrified wiring
is good for vermin control and dry areas. One of
advantage of multiple wired fence is it can be extend
up to 500m‐1000m. In the single wire fence it is
impossible to send electrical impulse through more
than 1000m of soil.
For fence wiring use galvanized wires. If the length of
the fence is less than 300m, use poly wires or poly
tapes.
Fig. 1.5 - Test point waveforms and voltages. Channel 1 : Test Point A & Channel 2 : Test Point B
IC Pins Voltage
IC1 1
4.5V ‐ 5.2V 8 (GND)
IC2 4 (GND)
4.5V ‐ 5.2V 8
IC3 1 (GND)
4.5V ‐ 5.2V 8
IC4 1
9.5V ‐ 12.3V 6 (GND)
IC5 8 (GND)
16 4.5V ‐ 5.2V
Table 1.1 - Supply voltages to the selected ICs
‐ 5 ‐
Component list
C1 0.1MFD R1, R3, R13 22k (M0805)
C2, C3 0.0033MFD R2, R20 68k (M0805)
C4, C8 0.01MFD R4, R5 4.7k (M0805)
C6, C12, C13 0.1MFD R6, R7 47k (M0805)
C10, C11 0.33MFD R8 820Ω
C5 3.3MFD/16V R9 22k
C7, C9 10MFD/16V R10 12k (M0805)
C14 1000MFD/50V R11, R21 1k (M0805)
T1, T2, T3, T4 MMBT3904 R14, R24 330Ω (M0805)
Q1 TIP122 R15, R16, R17 330k (M0805)
Q2, Q3 IRFZ44 R18 100k (M0805)
Q4 BC557 R19 10k (M0805)
Q5 2SC3611 R22, R23 15k (M0805)
T5 2SD400 R12 Vishay T7YB 47K 10% TU
FIT1 Murata DSS6NC52A102Q55B VR1 10K ‐ SONY Potentiometer (LOG)
IC1 PIC12F675P L1 BL01RN1A ‐ Wire wound bead inductor
IC2 LM393N L2 82114A ‐ Wire wound inductor
IC3 NE555 DM1 AL‐009SS ‐ 11 segment LED bar‐graph array
IC4 TDA7052 D1 U57X32 LED (Red)
IC5 HEF4017N D2 1N5402
IC6 UA7805TV RLE1 SYSTEK 12V ‐ 250V (3A) SPDT Relay
IC7 UA7812TV S1 6mm × 6mm tactile switch
J1, J2, J3 , J4, J5, J6, J7, J8
6mm spade crimp solder terminals
TP1, TP2, TP3 Test point terminals
X1 2pin PCB terminal block (508mm)
All the resistors marked as M0805 are SMD ‐ 0805 size ‐ 1/8W resistors.
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33
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HEF4017N
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7805TV
7812TV
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0.33MFD
0.1MFD
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GND GND
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VCC1
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GP0/AN07
GP4/AN33
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3
1
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6
5
7
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C6
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OUT28
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GND13
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IC4
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C7
C8
Q5
C9
T5
R23
21
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J4
J5
J6
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Q51
Q12
Q03
Q24
Q65
Q76
Q37
Q89
Q410
Q911
CO12
ENA13
CLK14
RES15
IC5
DM1
VI1
2
VO3
IC6
GND
VI1
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Q4
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C5
C6
IC4
C7
C8
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C9
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J5
J6
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IC6 IC7
C10
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C12
C13
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J7
J8
D2
C14
TP1
TP2
TP3
HT1N1
N2
N3
N4
N5
N8
N6
N7
N9
N11
N10
N12
N13
N14
N15
N16
N17
N18
N19
N20
N21
N22
N23
N24
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820R
TIP
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IRF
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IRF
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TRNS1
TRNS2
22K
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C393N
47K
LIN
BC
557
BL01R
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3.3
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6V
0.1MFD
TDA7052
10M
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/16V
0.0
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FD
1751248
2S
C3611
10M
FD
/25V
2S
D400
ACIN
ACIN
ACIN
U57X32
HEF4017N 7805TV 7812TV
0.3
3M
FD
0.3
3M
FD
0.1
MF
D
0.1
MF
D
8211
4A
DC_IN
GND
1N
5402
1000MFD/50V
R1
R2
R3
T1
T2
R4
R5 R6
R7
T3
R10
R11
R13
R14
R15
R16
R17
R18
R19
R20 R21
R22 T4
R23
R24
22K
68K
22K
MM
BT
3904
MMBT3904
4.7K
4.7K 47K
47K
MMBT3904
12K
1K
22K
330R
330K
330K
330K
100K
10K
68K 1K
15K
MMBT3904
15K
330R