Many electronics circuits and projects for learning in simple ways.

DC Boost Converter circuit 3.3-5v to 12V-13.8V

This is DC boost converter circuit that can use 3.3V to 5V power supply source into DC 12V-13.8V output max current 100mA. It is switching circuit better than the old circuit.

You can increase low voltage battery to high voltage load as you need with high efficiency

My son bought LED light Bulb a few days ago. As Figure 1. It is cheap and super bright. It is used for 12V power supply only. But he does not know its power consumption. Thus, he wants to measure its current.


Figure 1 LED light Bulb for car

He uses the ammeter to measure a current of the LED as Figure 2 circuit diagram and Figure 3 real measuring current.

measuring current 12V LED
Figure 2 measuring current circuit diagram

real measuring current LED light
Figure 3 the real measuring current LED light by my son

He read ammeter is 0.024A or 24mA only, it uses low current and power consumption

But My son has 3x 1.2V AA battery that 3.6VDC as Figure 4
So it cannot be used for the 12V LED light bulb.

3 AA battery 1.2V is connected in series
Figure 4 as 3 AA battery 1.2V is connected in series

We need the DC boost converter circuit to convert input 3.6V to 12V output.

DC Boost Converter circuit 33-5v to 12-138v
As Figure 5 the circuit diagram of DC boost converter

This circuit can help him because:

Special feature

  • Used for a power supply, 3.3-5 volts 750 mA up
  • Can apply voltage 12-13.8 volts depends on the power supply input
  • If using the power supply of 5 volts DC current 300mA can apply the output; voltage is 12 volts DC at 100 mA maximum
  • If using the power supply of 3.3 volts DC current 660mA can apply the output; voltage to 12 volts DC at current maximum to 50 mA
  • Maximum current output: 100 mA
  • Normal Switching frequency about 43 KHz
  • Can adjust the output voltage
  • There is power on LED display

How it works
The circuit will show in Figure 5, the operation starts with when we apply the power supply to the circuit. The IC1 will act as the step-up voltage converter. The voltage will increase to pin 1 of IC1-KA34063 through diode D1 to OUT point. We can adjust the output voltage by adjusting at VR1.

How to assemble circuits
He bought the project as PCB board so easy to use but you can buy all parts as the list below. Then, you may assemble circuits on the perforated board or DIY Glass Fiber Prototyping PCB Universal Board.

Testing and how to use
As Video below We try to experiment with LED use the 3.6V battery again. The LED will without the light.
Then, He connects the wires or the power cable to LED easy to use.
And Then He tests the circuit

On the PCB; He connects the power line 4, the terminal of the circuit.
As Figure 6: Testing This DC-step-up-converter citcuit using KA34063
testing-DC-step-up-converter citcuit using KA34063

– Apply the 3.6V battery to the input terminal.
– Apply the LED to the output terminal and measure the LED voltage.
– Adjust the VR-10K until we read voltage is 12V
– Measure current of LED is 24mA at voltage 12V
– Measure current of the circuit is 100mA at 3.9V

Thus we have power input is 0.1A x 3.9V = 0.39W
but we can use load (LED) at power 0.025A x 12V = 0.3W
We will see that use low voltage input make we have high voltage output at low power using.

– IN point ; for Connect power supply 3.3-5 volts DC.
– OUT point; is used as DC power supply to any loads which this voltage is changed by the input voltage and adjust at VR10K.

Parts you will needs

Resistors 0.25W
R1—100 ohms -brown-black-brown-gold
R6-R8—1K -brown-black-red-gold
Resistors 1/4W
R2-R5—1 ohms -brown-black-gold-gold
Trimmer Potentiometer
VR1–103 or 14 or 10K
Ceramic Capacitor
C1—681 or 680pF
Electrolytic Capacitors
Note: I bought this kit. I did not design this circuit myself. I am just using it before you. I am happy that it works well. I want to see you happy like me.

Keep reading: ‘Step up converter circuit’ »

This Post Has 8 Comments

  1. I want to make solar panel mobile battery charger.I have 3watt solar will I know its voltage?

  2. Sir,
    I am most impressed with all your circuits especially teaching your son really this is so GOOD.
    I want to build a project of your and need to buy n IC KA34063 I am not familiar with this IC also WHER C|AN I BUY THIS Please.
    Your reply would be sincerely appreciated.

    Thank you for your projects.
    New Zealand.

  3. Cool circuit. What is the value of that COIL ?

  4. hello, I printed the page to test the diagram. but the coil rating/value was not there… could you please mention the value of the coil . thanks in advance.

  5. what is the value of the coil ?

  6. Hello what is the value of coil? thanks

  7. Kindly tell something about inductor you used and of what value and how do you made it.
    Thank You

  8. What is the value of that COIL ?

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