This post shows you how to build a simple electric fence charger.
This is a safe and affordable way to keep your pets inside your yard and wild animals out.
It is a good alternative to a regular fence because it is cheaper and easier to fix.
WARNING: Electric fences can be dangerous if not built correctly.
Only do this project with adult supervision.
What is a High Voltage Fence Charger Circuit:
A High Voltage Fence Charger Circuit is an electronic circuit designed to generate a high voltage pulse that is used in electric fence systems.
Electric fences are often used in agriculture and security applications to deter animals or intruders by delivering a non lethal electric shock when they come into contact with the fence.
The high voltage pulse is typically short in duration making it uncomfortable but not harmful.
Construction Details:
Use one or more wires ensuring they are adequately stretched above the ground.
Isolate the wires from the ground to prevent unintended grounding.
Employ a common automotive ignition coil to generate high voltage pulse.
Utilize a MOSFET transistor controlled by a 555 circuit to ensure precise pulse interruption.
Set the pulse repetition frequency to approximately 1.3 Hz using resistor R1.
Adjust the duty cycle to about 2% by controlling the ON time of the transistor with resistor R2.
Manage both frequency and intensity by selecting capacitor C1.
For increased intensity or frequency consider employing a more powerful transistor.
Circuit Description:
Parts List:
| Component | Description | Quantity |
|---|---|---|
| Resistors | 1/4 W CFR | |
| 18k | 1 | |
| 1M | 1 | |
| 15Ω | 1 | |
| Capacitors | ||
| PPC | 330nF 250V | 1 |
| Electrolytic | ||
| 4700µF 16V | 1 | |
| 1µF | 1 | |
| Semiconductors | ||
| Diode | 1N4148 | 1 |
| MOSFET | IRF830 | 1 |
| IC | 555 | 1 |
| Automobile ignition coil | 1 |
Below mentioned is the circuit descriptions:
- 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 more potent electric pulse is desired a higher capacity transistor may be considered to handle increased power requirement.
Formulas and Calculations:
For the 555 IC astable circuit the below are the component values:
- R1 = 1M (resistance 1)
- R2 = 18k (resistance 2)
- C1 = 1µF (capacitance)
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 (approximately 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 = 98.2% (Since R1 is much larger than R2, the charge time dominates, 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 constructed, delivers short, low current electric shocks, posing no significant danger to humans or animals.
- The unpleasant electric shock prompts animals to avoid contact with the fence.
- The system can replace or complement traditional fences providing a versatile solution.
Disclaimer:
The construction and utilization of the simple high voltage fence charger circuit are undertaken at your own risk.
This equipment is capable of delivering electric shocks, and the author disclaims responsibility for any damage or consequences resulting from the use of this device.
Users are advised to exercise caution and follow safety guidelines during construction and operation.
Conclusion:
It is important to note that the design and implementation of a high voltage fence charger circuit can vary based on the specific requirements and scale of the electric fence system.
Additionally, safety considerations are paramount and users should exercise caution when working with high voltage circuits.