To implement a simple street lamp control circuit, we can utilize the following components and design principles:

Components:

1. Microcontroller or Arduino board: A microcontroller like Arduino can be used to program and control the street lamp operation.
2. Light sensor: A light-dependent resistor (LDR) or a photodiode can be used to detect the ambient light level.
3. Relay module: A relay module can be used to switch the street lamp on or off.
4. Power supply: Depending on the street lamp's power requirements, you can use a suitable power supply, such as a battery or a dedicated power source.

Design Principles:

1. Light Sensing: Connect the LDR or photodiode to one of the analog input pins of the microcontroller. Read the sensor's value periodically to determine the ambient light level.
2. Threshold Setting: Establish a threshold value to differentiate between day and night. This threshold value can be determined experimentally based on the desired sensitivity of the street lamp.
3. Control Logic: Implement control logic in the microcontroller to determine when to turn the street lamp on or off. For example, if the detected light level is below the threshold, activate the street lamp; otherwise, deactivate it.
4. Relay Control: Connect the relay module to one of the digital output pins of the microcontroller. Use the appropriate transistor or optocoupler circuit to interface the microcontroller with the relay module. Activate the relay module when the street lamp needs to be turned on.
5. Power Supply: Connect the power supply to the street lamp and the relay module, ensuring that the voltage and current ratings are appropriate for the lamp's requirements.

Overall Circuit Diagram:
Here's a simplified circuit diagram: