Transformerless Capacitive Power Supply for LED/Acid Battery

In this electronics project, I design and make a power supply circuit without a transformer. There are many methods to convert the mains AC voltage to lower DC voltage, the Capacitive power supply is one of them.

This Transformerless circuit can provide 0 to 18 volts output from input 230 V mains voltage. It can vary the output voltage by replacing a suitable Zener diode. This circuit can drive a 1/3/5 watt LED, and charge an acid battery easily. Let's make it.

Components List

The following components are required to make a transformerless power supply.

  1. 0.68uF 400 V X-rated capacitor.
  2. 1M Ohm 0.25 W resistor.
  3. 100 Ohm 2 Watt resistor.
  4. 1N4007 diode (D1 to D4).
  5. 220uF 16 V Capacitor.
  6. 5mm LED.
  7. 1K 0.25 W resistor.
  8. 0.5 W Zener diode.
  9. 100 Ohm 0.25 W resistor.

Transformerless Capacitive Power Supply Circuit Diagram

Schematic of the transformerless capacitive power supply circuit shown below.

Circuit Explanation

  • 684J 400V Voltage Dropping Capacitor reduces the mains AC voltage to low AC voltage.
  • For removing the storage current from the voltage dropping capacitor 1M ohm used.
  • 100 Ohm 2 Watt resistor protects the circuit from inrush current at the mains.
  • Diode D1 to D4 are 1N4007 and they work together as a full-wave bridge rectifier to rectify the low AC voltage from the voltage dropping capacitor.
  • Removing the ripples from DC a 16V 220uF capacitor used.
  • A 3mm red LED used as a power ON indicator, and 1K 0.25 Watt resistor protects the LED.
  • As per the required output voltage a suitable 0.5 Watt Zener diode used in this transformer power supply circuit. In my case, I used a 5V 0.5 Watt Zener diode. You can choose different value Zener diode like 9v, 12v or 15v. A 100 Ohm 0.25 Watt resistor is important to connect in series with the Zener diode (it does not affect the output voltage). Otherwise, Zener will be destroyed.

The capacitive power supply is not for beginners, there is a chance for a fatal shock if anyone touched the circuit. Everything you do at your own risk, for any injury to health or property I do not take responsibility!

After Soldering this Circuit in PCB

After Soldering the transformerless capacitive power supply circuit in PCB, side views are shown below.

Transformerless Capacitive Power Supply Circuit Board
Circuit Board (Side View: 1)

Transformerless Capacitive Power Supply Circuit Board
Circuit Board (Side View: 2)

Demo & Testing

Transformerless Capacitive Power Supply can Drives a 1/3/5 Watt LED
This power supply can drive a 1/3/5 Watt LED easily.

Transformerless Capacitive Power Supply can Charge an Acid Battery
This power supply can charge a 4/6/12 volts Acid battery.


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