This backyard lamp circuit is like a smart switch for your outdoor lights.
It uses a special light sensor LDR to tell the difference between daytime and nighttime.
At night, the circuit turns on your backyard lamp automatically.
Then, in the morning when it gets light again, the circuit turns the lamp back off.
It does this using a tiny chip CD 4060 that acts like a timer.
Circuit Working:
Parts List:
| Component Type | Description | Quantity | Notes |
|---|---|---|---|
| Resistors | 470k | 1 | |
| 100Ω 1W | 1 | 1 watt resistor | |
| 10M | 1 | ||
| 1M | 2 | ||
| 220Ω | 2 | ||
| Preset | 100k | 1 | |
| Capacitors | Ceramic 105 400V | 1 | |
| Ceramic 0.22µF | 1 | ||
| Electrolytic 1000µF 40V | 1 | ||
| Semiconductors | IC 4060 | 1 | |
| LDR | 1 | Light Dependent Resistor | |
| Triac BT136 | 1 | ||
| LED | Red 5mm 20mA | 1 | |
| Bridge Rectifier | 1N4007 | 4 | |
| Diode | 1N4148 | 1 | |
| Lamp | 60W | 1 | Incandescent lamp |
This simple backyard lamp circuit automatically illuminates your backyard at 10 pm and remains on until morning, providing light to deter nocturnal animals and prevent theft.
It operates using a light dependent resistor LDR as a light sensitive switch.
The circuit features a transformerless power supply and a timer-based switching circuit.
Capacitor C1, diodes D1 to D4 and capacitor C2 make up the power supply section.
C1, an X rated AC capacitor reduces high AC voltage to a safer level via capacitance reactance.
Diodes D1 to D4 form a full wave rectifier to convert AC to DC and capacitor C2 smoothens the DC output.
Resistor R1 acts as a bleeder resistor to discharge C1 when the circuit is off and resistor R2 limits the inrush current.
The LDR triggers IC1 at sunset.
The LDRs resistance is high around 10 meg in darkness and low 100 ohms or less in bright sunlight.
The CD 4060 IC is ideal for long time delay applications serving as a binary counter with an internal oscillator and 10 current sourcing outputs.
During the day, the low resistance of the LDR keeps reset pin 12 of IC1 high preventing its operation.
At sunset, the increasing resistance of the LDR grounds pin 12 initiating oscillation with components C3, R4 and R5.
The flashing red LED indicates IC1 activation.
With the specified values of C3, R4 and R5 pin 1 goes high after 4 hours around 10 pm.
When pin 1 goes high the Triac fires to complete the lamp circuit.
Simultaneously, diode D5 forward biases, stopping IC1s oscillation.
IC1 remains latched until morning providing a high output at pin 1.
In the morning, the LDR receives light again resetting IC1 which remains off until sunset.
Enclose the circuit in a shock proof case with the LDR exposed.
Place the unit where sunlight is available and keep the lamp away from the unit to prevent its light from affecting the LDR.
VR adjusts the LDRs sensitivity at the desired light level.
Placing the LDR in a black tube makes adjustments easier at the specified light level.
This circuit is not suitable for CFL or fluorescent lamps, as the triac may not provide full supply voltage potentially damaging the electronic circuitry in these devices.
Caution:
This circuit is directly connected to mains power without galvanic isolation.
Do not test or troubleshoot when connected to mains.
Adjust VR only with a sleeved screwdriver, and do not touch any parts when the circuit is powered.
Formulas:
Using the IC 4060 to design a backyard lamp circuit entails building a timer circuit that regulates a lamps on/off cycle according to a timing sequence the IC 4060 generates.
The timing interval of the IC 4060 is determined by an external resistor R4 +R5 and capacitor C3 in our above circuit diagram.
The following formula may be used to approximate the frequency f of the oscillator within the IC 4060 and, consequently, the timing period T:
T = 2.3 × R1 × C1
In our circuit R1 = R4+R5 and C1 = C3 by substituting these figures in the above equations, we get:
T = 2.3 × (R4+R5) × C3
where,
- The resistance that is attached to the IC 4060s oscillator pin is denoted by R4 and R5.
- The capacitance that is attached to the IC 4060s oscillator pin is denoted by C3.
Note:
This method and conceptual circuit diagram serve as a foundation for building an IC 4060 timer IC based backyard lamp control circuit.
Achieving the required time interval for efficient light control will require fine tuning component values.
How to Build:
To build a Simple Backyard Lamp Circuit using IC CD4060 below mentioned are the steps:
Safety First:
- Ensure you are familiar with working around mains power and take appropriate safety precautions.
- Work in a well ventilated area and use insulated tools.
Power Supply Section:
- Connect C1 in series to the mains to reduce voltage.
- Use D1 to D4 to create a full wave rectifier for converting AC to DC.
- Smooth the DC using C2.
- Use R1 as a bleeder resistor to discharge C1 when the circuit is off.
- R2 limits the inrush current.
Timer Section:
- Use the LDR to trigger IC1 at sunset.
- IC1 CD 4060 is a binary counter with an internal oscillator and 10 current sourcing outputs.
- At sunset, the increasing resistance of the LDR grounds pin 12 of IC1 starting oscillation with C3, R4 and R5.
- The flashing red LED indicates IC1 activation.
- With specified values of C3, R4 and R5, pin 1 goes high after 4 hours adjustable with VR.
Lamp Control:
- When pin 1 goes high, the Triac fires to complete the lamp circuit.
- D1 forward biases, stopping IC1s oscillation.
- IC1 remains latched until morning, providing a high output at pin 1.
- In the morning, the LDR receives light, resetting IC1 which remains off until sunset.
Enclosure:
- Enclose the circuit in a shock proof case with the LDR exposed.
- Place the unit where sunlight is available and keep the lamp away from the unit to prevent its light from affecting the LDR.
- VR adjusts the LDRs sensitivity at the desired light level.
- Placing the LDR in a black tube makes adjustments easier at the specified light level.
Note:
- It is highly recommended to consult with a professional or someone experienced in working with mains powered circuits before attempting to build this circuit.
Conclusion:
To conclude, this simple backyard lamp circuit provides a simple and efficient way to illuminate your backyard automatically helping to deter nocturnal animals and prevent theft.
However, it is important to note that working with mains voltage can be dangerous so caution should be exercised when building and testing the circuit.