Transformerless 12V Power Supply Circuit for Low-Power Devices

⚡ Work & Installation (Input → Output):

A transformerless 12V power supply provides a compact and cost-effective solution for powering low-current electronics without using a bulky transformer. It uses a series capacitor or resistor to drop the AC mains voltage, followed by rectification and filtering to produce a 12V DC output. Ideal for LED lighting, small sensors, and DIY electronics projects, this design is energy-efficient and inexpensive. While not isolated from mains, careful insulation ensures safety. This guide explains the working principle, input-to-output connections, and safe installation, helping hobbyists and electronics enthusiasts implement a simple 12V DC supply for low-power applications.

Testing & Final Adjustments:

After assembling the transformerless 12V power supply, carefully connect it to the AC mains and measure the DC output using a multimeter. Ensure the output voltage is around 12V; if necessary, adjust the series capacitor value or add a Zener diode for regulation. Check all connections, especially the series capacitor and diodes, to prevent overheating or failure. Confirm the current drawn by the load does not exceed the designed limit, as the circuit is meant for low-current applications only. Always avoid touching live parts and insulate exposed wires to ensure safety. For improved stability, a small filter capacitor can be added at the output. Once tested, this power supply can safely provide 12V DC to small electronics, LED lighting, and sensors. Proper testing, insulation, and adherence to current limits ensure reliable operation while keeping the design compact, energy-efficient, and cost-effective for DIY enthusiasts and hobbyists.