12 Volt Capacitor Power Supply


About 8566 readers of this Blog visited the transformer less power supply article posted and there are queries regarding the design of the circuit to power different types of gadgets. So one more circuit is posted here that can give 12 volt DC at 300 milli amperes current. This circuit uses AC capacitor to drop the AC power to generate 12 volt DC.


The main element of this power supply is three 1 uF 400 Volt X rated capacitors C1 through C3. Each 1 uF capacitor can give 100 mA output current. Since the three capacitors are connected parallel, 300 milli ampere current will be generated. The 1uF capacitor drops the 230 volt AC to around 50 to 60 volt AC depending on the AC input voltage. Resistor R1 is provided to bleed the stored current in the capacitors when the circuit is unplugged. Without R1, the capacitor retains around 400 volts for many days, which can give a fatal shock. Resistor R2 is also important to restrict the inrush current at power on. The 50-60 volt AC from the capacitor is rectified by the full wave rectifier formed of D1 through D4. After rectification, the DC will be regulated to 15 volt by the Zenerdiode. Resistor R3 limits the Zener current. By changing the value of Zener, output voltage from 6 volts to 30 volts can be produced. LED is provided to indicate power on status. This LED will consume 2 volts, so that output will be around 12-13 volts.

12 Volt Capacitor Power Supply

Note: This circuit has no galvanic isolation from the mains. So any short circuit can destroy the capacitor and the gadget connected to it. Do not use this circuit to power costly gadgets. It is better to add a safety fuse and MOV at the input to protect the power supply from damage.

Caution: This circuit is extremely dangerous if handled without precautions. Most points are at mains lethal potential and can give fatal shock. So do not try this circuit unless you are competent to handle high voltages. Do not touch any points when the circuit is connected to mains. Always enclose the circuit in a shock proof case.

D.Mohankumar

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17 thoughts on “12 Volt Capacitor Power Supply

  1. PK 5 Mar 2012 / 11:07 am

    Hello Sir,
    Thanks for this great circuit,
    I have Bright 1 Watt led’s (3.4v, 300 mA) and I am planning to replace CFL’s. I will use CFL holders. For regular LED’s space is minimal, so i want to use 1 watt LED’s.
    Kindly guide me how to use this circuit for say 3 watt, 6 watt, 9 watt and 12 watt LED’s in series or parallel using these LED’s.
    Regards.

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  3. PK 4 Mar 2012 / 7:19 am

    Hello Sir,
    Thanks for this great circuit,
    I have Bright 1 Watt led’s (3.4v, 300 mA) and I am planning to replace CFL’s. I will use CFL holders. For regular LED’s space is minimal, so i want to use 1 watt LED’s.
    Kindly guide me how to use this circuit for say 3 watt, 6 watt, 9 watt and 12 watt LED’s in series or parallel using these LED’s.
    Regards.

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  5. dg4666 13 Nov 2011 / 1:32 am

    sir
    can i use 475k,400v x rated capacitor in the place of three 105k,400v capacitor.

  6. Darshana 2 Nov 2011 / 4:48 am

    Dear Sir, thanx mohan sir, is it possible to get around 36volt / 300 mili amperes using these kinds of supplies”, is it possible mohan sir?

    • D.Mohankumar 2 Nov 2011 / 2:37 pm

      Dear Darsana
      From the capacitor, you will get around 40-60 volts. Use a zener of specified voltage

      • Darshana 3 Nov 2011 / 6:04 am

        Dear Sir, Please send to circuit Diagram of 36v 300ma capacitor power supply

      • D.Mohankumar 3 Nov 2011 / 1:29 pm

        Hello Just replace the 12 volt Zener with a 36 volt zener. No other change. D.Mohankumar

  7. Diljith Andody 20 Oct 2011 / 4:50 am

    Hello sir, today I seek for a 12v 300ma transformer less power supply for a LED lamp, finally I get your page, Thank you, I am Diljith, Kozhikode, an electronic service professional, today I will make it. Thank you

    • D.Mohankumar 20 Oct 2011 / 12:28 pm

      Go ahead and make a simple power supply. Take care. It is directly powered from AC and avoid touching the PCB to prevent shock.

  8. loneziddik 19 Oct 2011 / 2:25 pm

    thanx mohan sir, some people ask me that “is it possible to get around 2 or 5 amperes using these kinds of supplies”, is it possible mohan sir?

    • D.Mohankumar 19 Oct 2011 / 3:22 pm

      Hello With the capacitor power supply it is possible to get 100 – 300 mA current. So these are used in low power applications only. For high current, transformer is necessary. D.Mohankumar

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