Twilight Switch LED Lamp

Overview

A practical and elegantly designed night lamp featuring a twilight switch. This kit allows you to build a lamp that illuminates with bright LED light after dark.

Specifications

• Lightsource: 3 white LED diodes
• Smooth adjustment of light sensitivity
• Power supply: 5VDC (requires 3 x R6/AA batteries, not included)

Schematic Diagram

Figure 1 shows the electronic schematic diagram of the Twilight Switch LED Lamp. The circuit uses a voltage divider formed by the photoresistor (PH1) and potentiometer (PR1) to control the base of transistor T1. In low light conditions, the resistance of PH1 increases, reducing the voltage at the base of T1. This turns T1 off, which in turn allows transistor T2 to turn on. T2 then provides current to the three white LEDs (LED1, LED2, LED3), illuminating them. The potentiometer (PR1) allows for adjustment of the light sensitivity threshold. The circuit is powered by a 5VDC source, typically from batteries.

Key components include:

• SW1: Switch
• PH1: Photoresistor
• PR1: 10kΩ Potentiometer
• R1: 4.7kΩ Resistor
• R2: 3.3kΩ Resistor
• R3-R6: 33Ω Resistors
• C1, C2: 10μF Capacitors
• T1, T2: BC548 Transistors
• LED1, LED2, LED3: White LED Diodes

Component Placement on Circuit Board

Figure 2 illustrates the layout of components on the printed circuit board (PCB). Components are arranged to facilitate soldering and assembly. Key components like LEDs, transistors, resistors, capacitors, the photoresistor, potentiometer, and switch are positioned strategically. The battery connector is also clearly marked.

Photo 1 shows the installation of the LED diodes, highlighting their correct orientation.

Suggested Order of Assembly

It is recommended to solder components onto the circuit board in order from smallest to largest.

• R1: 4.7kΩ resistor (Color code: yellow-violet-red-gold)
• R2: 3.3kΩ resistor (Color code: orange-orange-red-gold)
• R3-R6: 33Ω resistors (Color code: orange-orange-black-gold)
• PH1: Photoresistor
• LED1-LED3: 3mm white LED diodes
• C1, C2: 10μF capacitors
• T1, T2: BC547 or BC548 transistors
• PR1: 10kΩ potentiometer
• SW1: Switch
• Battery sockets: Red terminal for positive ➕, Black terminal for negative ➖

Soldering Process

Follow these steps for proper soldering:

1. Touch the tip of the soldering iron [soldering iron tip] to the end of the component lead and the soldering pad on the PCB simultaneously.
2. Apply tin solder to the heated joint until a small cone of solder forms [solder cone].
3. Remove the solder first, then lift the soldering iron.
4. The entire process for a single joint should take approximately 2-3 seconds.

Important Soldering Notes:

• Ensure clean soldered surfaces, adequate flux, and correct temperature (320-360°C) for a strong bond.
• Excessive solder can create a ball or bridge adjacent points.
• Insufficient heat or solder can result in "cold solder joints," which are fragile and prone to failure.

Component Polarity and Orientation

• When assembling components marked with a warning symbol ⚠️, pay close attention to their polarity and orientation (e.g., notches on transistors, flat sides of LEDs).
• For LEDs (LED1-LED3), the longer lead is typically the anode (positive ➕) and the flat side of the casing indicates the cathode (negative ➖).
• For electrolytic capacitors (C1, C2), the lead marked with a stripe (usually on the casing) is the cathode (negative ➖).
• For transistors (T1, T2), align the flat side [flat side] or notch [transistor notch] as indicated on the PCB to ensure correct pinout (e.g., Emitter, Base, Collector).

Important Information and Safety Precautions

Thank you for purchasing this AVT product. Please read the following information carefully before use.

• Educational Use: This kit is intended for educational and demonstration purposes only. It is not designed for commercial applications.
• Responsibility: Purchasers are responsible for ensuring compliance with all local laws if used in applications beyond educational demonstration.
• System Integration: This kit cannot be used as part of life support systems or any system that could create a hazardous situation.
• Power Sources: Battery or wall adapters are generally safe. Exercise caution if connecting to mains voltage via a relay.
• High Voltage/Current: If the kit is used to switch currents greater than 24V, installation must be performed by a trained professional, and the kit must be housed in a safe enclosure.
• Ratings: Never exceed the limits or ratings specified in the 'Specifications' section.
• Supervision: In schools or educational facilities, operation must be supervised by trained and authorized staff.
• Child Safety: The product and its parts are not toys and are unsuitable for children due to choking hazards and risk of electric shock.
• Troubleshooting: Most kit failures (over 95%) are due to poor soldering or incorrect component placement/orientation. Please check your work carefully.

Manufacturer Information

AVT SPV Sp. z o.o.

Leszczynowa 11 Street,
03-197 Warsaw, Poland

Website: http://avtkits.com/

Disclaimer: AVT SPV reserves the right to make changes without prior notice. Assembly and connection of the device not in accordance with the instructions, unauthorized modification of components, or any structural modifications may cause damage to the device and endanger the user. In such cases, the manufacturer and its authorized representatives shall not be liable for any damages arising directly or indirectly from the use or malfunction of the product.

Environmental Disposal: ♻️ This symbol indicates that the product should not be disposed of with household waste. Protect human health and the environment by handing over waste equipment to a designated collection point for the recycling of waste electrical and electronic equipment.