Diagram of the steps to make DIY wireless LED lights

This project features a high-frequency switching transistor, the BD139, which is known for its strong performance and ability to enhance signal output. As the saying goes, "the greater the power, the greater the responsibility." This means that using such a device requires caution. It should not be placed near sensitive electronics like hard drives or other delicate components, as it can create high-frequency interference that might damage your equipment. Always take safety precautions when working with transformers, and use insulated bushings to prevent electric shocks. Avoid using power adapters or batteries in this setup.

Additionally, this wireless LED light is a great educational tool for demonstrating electromagnetic induction principles. The materials required are simple and easy to find. Here’s what you’ll need:

• 2 x 2-turn coils
• 33k ohm resistor
• 100nF capacitor (also labeled as 104)
• 100μH inductor
• One LED (red, orange, or red patch works best)
• BD139 transistor (or similar)
• Bridge rectifier (can be made using 4x 1N4148 diodes)
• Perforated board (3x3cm)
• Wires, solder, and a power source (6-12V)

Step 1: Gathering Materials

Coils can be made from old magnetic rings, while transistors, resistors, and capacitors are commonly available at local electronics stores. Inductors can be either salvaged from old circuit boards or wound around a ferrite core. A small bridge rectifier can also be built if needed.

Step 2: Building the Mini Bridge Rectifier

To build the rectifier, you’ll need four 1N4148 diodes. Connect them according to the schematic, ensuring correct polarity (black line indicates negative). Solder the connections carefully to avoid any short circuits.

Step 3: Soldering the Circuit

Follow the schematic to assemble the circuit on a perforated board or breadboard. Be careful when soldering the coil to maintain its shape and alignment. For SMD LEDs, attach leads to the pads, while through-hole LEDs can be directly connected to the coil without worrying about polarity.

Step 4: Understanding the Principle

This project demonstrates mutual induction. The transmitter coil generates a magnetic field, which induces a current in the secondary coil connected to the LED, creating an electromagnetic field that powers the LED wirelessly.

Step 5: Testing and Troubleshooting

Testing the circuit involves connecting the oscillator to a DC power supply (6-12V), placing the drive coil on a stable surface, and holding the LED coil parallel to it. Bring the LED coil close to the oscillating one without touching. You may notice the transistor warming slightly, but this is normal. If everything works, the LED should light up.

If the LED doesn’t light up, check the following:

• Ensure all solder joints are secure and clean.
• Avoid poor contact between components.
• Make sure the coil is perfectly round and aligned.
• Adjust the distance between the two coils for optimal performance.
• If the coil is misaligned, the LED brightness may decrease.

With a little patience and attention to detail, this project is a fun and educational way to explore the basics of wireless power transfer and electromagnetic induction.