The construction of a simple electric fence charger is discussed in this post.
It is a cost effective and safe method of keeping wild animals out of the fence and pets within.
Because it is less expensive and simpler to maintain, as it is good option against standard fence.
WARNING: Electric fences can be deadly if not constructed correctly.
This task should only be completed under adult supervision.
What is a High Voltage Fence Charger Circuit:
For usage in electric fence systems a high voltage pulse is generated by an electrical circuit known as a high voltage fence charger circuit.
In agriculture and security applications electric fences are often used to keep away animals or thieves by shocking them with electricity when they come into contact with the fence.
Because the high voltage pulse usually lasts only for a short time but it is painful yet, safe.
How to Build:
To build a Simple High Voltage Fence Charger Circuit following are the steps required for connections:
- Ensure the wires are sufficiently extended above the ground before using one or more of them.
- To avoid accidental grounding disconnect the wires from the ground.
- Use a standard car ignition coil to produce a high voltage pulse.
- To ensure an accurate pulse interruption use a MOSFET transistor that is regulated by a 555 circuit.
- Using resistor R1 and set the pulse repetition frequency to around 1.3 Hz.
- Using resistor R2 adjust the transistors ON time to get the duty cycle down to roughly 2%.
- Capacitor C1 allows one to control both frequency and intensity.
- Try out a more powerful transistor for higher frequency or intensity.
Circuit Working:
Parts List:
| Component | Description | Quantity |
|---|---|---|
| Resistors | All resistors are 1/4 W CFR | |
| 18k | 1 | |
| 1M | 1 | |
| 15Ω | 1 | |
| Capacitors | ||
| PPC | 330nF 250V | 1 |
| Electrolytic | 4700µF 16V, 1µF | 1 each |
| Semiconductors | ||
| Diode | 1N4148 | 1 |
| MOSFET | IRF830 | 1 |
| IC | 555 | 1 |
| Automobile ignition coil | 1 |
The automotive ignition coil is connected to a power source and is triggered by the circuit to generate high voltage pulses.
The 555 timer IC operates in astable mode generating a continuous square wave.
R1 along with the capacitor C1 sets the pulse repetition frequency.
A higher resistance in R1 results in a lower frequency while C1 affects both frequency and intensity.
The output of the 555 timer is connected to the gate of the MOSFET transistor.
The transistor acts as a switch allowing the high voltage pulses from the ignition coil to pass through the fence wires during its ON time.
Resistors R1 and R2 along with capacitor C1 provide flexibility in adjusting the frequency and intensity of the electric pulses.
Users can fine tune these components based on the specific requirements of their electric fence.
If a stronger electric pulse is needed a transistor with a larger capacity would seem to be capable to handle the higher power demand.
Formulas and Calculations:
The formulas with calculations for Simple High Voltage Fence Charger Circuit is mentioned below:
For the 555 IC astable circuit following are the calculations:
R1 = 1M
R2 = 18k
C1 = 1µF
We can calculate the following:
Time Constant 1 (Charge Time):
T₁ = R₁ * C₁
T₁ = 1,000,000Ω * 1µF
T₁ = 1 second (s)
Time Constant 2 (Discharge Time):
T₂ = R₂ * C₁
T₂ = 18,000Ω * 1µF
T₂ = 0.018 seconds (s)
We can calculate the frequency (f) using the following formula:
f = 1 / (ln(2) * (T₁ + T₂))
where,
- ln(2) is the natural logarithm of 2 which is around 0.693
- f = 1 / (0.693 * (1 s + 0.018 s))
- f = 1 / (0.693 * 1.018 s)
- f = 0.982 Hz (hertz)
Duty Cycle D:
D = (T₁ / (T₁ + T₂)) * 100%
D = (1s / (1s + 0.018s)) * 100%
D = (1 / 1.018) * 100%
D is 98.2% since R1 is much larger than R2 the charge time controls resulting in a high duty cycle
Summary:
- Oscillation Frequency (f) = 0.982 Hz
- Duty Cycle (D) = 98.2%
Safety Precautions:
- The simple high voltage fence charger circuit when properly built delivers a short low current electric shocks with no significant danger to humans or animals.
- Animals avoid contact with the fence as a result of the painful electric shock.
- The design provides a range of choices that can either enhance or replace standard fences.
Disclaimer:
One should be on its own risk while building and using the Simple High Voltage Fence Charger Circuit.
The writer does not take on any responsibility for any harm or consequences that may arise from using of this devices which has the potential to give electric shocks.
During construction and operation process users are advised to use precaution and follow to safety guidelines.
Conclusion:
One should remember the importance of the scale and particular needs of the electric fence circuit can affect how a high voltage fence charger circuit is designed and implemented.
Also users should safe when working with high voltage circuits because safety is of the top priority.