9V AC to 25V DC Converter




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This Circuit will convert 9V AC to 25V DC.This converter circuit uses simply components like Diodes and Capacitors for amplification.You can also change the capacitors value to increase your amplification.

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Step 1: Components Required


  • 9V,500mA ----1


  • 1N4007 ------ 3


  • 470uF,50V-----3


  • Connectors---2


  • General Purpose PCB

Step 2: Schematic Diagram

Step 3: Assembling the Schematic

I had soldered the Circuit according to Schematic in a General Purpose PCB.

Step 4: Operation of 9V AC to 25 V DC Converter Circuit

Basic Operation

We all know capacitor will charge and discharge.During charging it will get charged with maximum peak voltage that we are applying. The capacitor will discharge when the sine wave cross the zero voltage. The sine wave will oscillating between positive(+9V) and negative amplitude values(-9V). During oscillation the sine wave will cross Zero Voltage(0V). During zero voltage(0V) the capacitor will discharge. During discharge of capacitor the voltage will be greater than charged voltage. So amplification is done by capacitor C1 in first stage. This amplified voltage is get charged by Capacitor C2 in second stage and during discharge of capacitor C2 in the second stage the voltage will be further amplified. This amplified voltage will be rectified by third stage(3rd) to convert from AC to DC and the DC voltage if further amplified by C3 in the third stage. You can increase the capacitor value to increase your amplification.

Detailed Operation

Operation of 1st stage at time instant T1

At time T1 Point A will be positive.The diode conduct in forward direction so point B is also positive.Point C is negative at time T1.So the capacitor C1 will be charged.

Operation of 1st stage at time instant T2

At time T2 the point A will be negative voltage so the diode will not conduct.So point B will be zero voltage.At time T2 the point C will be positive voltage.This positive voltage get cancel by negative voltage on the capacitor.Because the point C is connected to negative terminal of capacitor.The negative terminal of capacitor contains negative charge.Because it get charged with negative voltage during time T1. Now the capacitor will discharge the positive voltage at positive terminal,so now the point B will be positive. This positive voltage will go to 2nd stage for further amplification

Operation of 2nd Stage at time instant T1

At time T1 the point D will be positive.At time T1 of 2nd stage the point E will also be positive because the point E will get the input form point B. At this time the point B will get positive voltage due to discharge of capacitor C1. So the point F is also positiveThe point D is positive and the point F is also positive. So the capacitor positive plate get charged with positive voltage.

Operation of 2nd Stage at time instant T2

At time T2 the positive terminal of capacitor C2 has already charged with positive voltage during time instant T1 of 1st second stage.At time T2 the point D will be negative so the capacitor C2 gets charged and discharged. The capacitor only discharge if there exists potential difference between two plates.

Operation of 3rd Stage

The 3rd stage is HALF WAVE RECTIFIER.Uses to convert AC Voltage into DC Voltage.In this 3rd stage the final amplification is done by capacitor C3.If you connect capacitor in parallel across rectifier circuit the voltage will be amplified.

I had also attached JPEG file for understanding the operation of circuit

Step 5: Steps to Increase the Amplification.

Method 1

You can increase the amplification by increasing the stages.For understanding see the above diagram.This is the one method to increase amplification.

Method 2

You can also increase or decrease amplification by changing the capacitor value.This is another method to increase amplification.


As the stages increases the voltage also get increasing,so you need to increase the capacitor withstanding voltage value.For example 470uF,100V.

Step 6: Safety Procedure

DC voltages are very dangerous when they amplified above certain voltage levels when compared to AC Voltages.

Because AC Voltage will have zero crossing and the DC Voltage will not have zero crossing.So protect you from touching the circuit with your hands.

Step 7: Video

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    6 Discussions


    Reply 2 years ago

    You have to put 9V,2A transformer instead of 9V,500mA transformer


    2 years ago

    Considering the cost of electrolytic capacitors, an active converter is cheaper and has a much better efficiency and more, it is regulated. Next, these networks can't deliver much power and their output voltage isn't stable or accurate. Decades ago, they were used to generate high voltages but with small current in old tv's.