How to make a simple 230Vac to 5Vdc transformerless Power Supply design?

How to make a simple 230Vac to 5Vdc transformerless Power Supply design.

Hello Friends, This article is how to make a simple 230Vac to 5Vdc transformerless Power Supply design. We will design such a circuit which will step down the voltages without using a transformerless.


Don't try this circuit, if you don't have much experience in Electronics or Electrical. Don't touch any parts of the circuit while testing or using. Because some points will get the mains supply. so should be careful and enclose the circuit while testing. 

We will use a capacitor for reducing the voltages. this is the reason for its name Capacitor Dropper this circuit has two names. Transformerless Capacitor Dropper power supply is drawn here.

230Vac to 5Vdc transformerless Power Supply
230Vac to 5Vdc transformerless Power Supply design

230Vac to 5Vdc transformerless Power Supply diagram,

I have a circuit which is operated at 230V AC and a LED is connected at the output of this circuit. this is very simple. The circuit which consists one series resistor Capacitor (dropper Capacitor), one resistor is connected in parallel with the capacitor, then I use a Bridge Rectifier, Filter Capacitor, regulator unit, and the last unit is a LOAD which is a LED in series with a current limiting resistor.

So in this article, we will find, how this power supply work. There will discuss different blocks of this power supply. We will also look at the formula of this power supply which can use to design a power supply according to our load requirement.

The 230Vac to 5Vdc transformerless Power Supply is a very popular circuit used in low-cost electronic devices. Like Emergency lights and mobile charger circuit.

230Vac to 5Vdc transformerless Power Supply,


So let’s start this is the main circuit diagram of capacitor dropper there are 5 blocks in this diagram.

1, Unit is a series resistor unit.

2, The block is a capacitor dropper in this unit we drop the voltages by the capacitor.

3, Unit is a bridge rectifier unit the rectifier unit converts the AC voltages into DC which have ripples on it.

4, We will use a capacitor which will remove the ripples.

5, The last unit is the voltage regulator unit I use LM7805 voltage regulator which fix output at 5vdc.

So this is the main block diagram of capacitor dropper. This article will learn how to design the power supply according to our requirements. Let’s take a look the formulas of 5Vdc transformerless Power Supply. These are the formula of transformerless power supply down in this article.

So Collect the required data for designing the 5Vdc Transformerless power supply.

So, First of all, determine the supply voltage which you want to step down. In my case, the output 5V and supply voltages are 230 V. The second important things you will need to determine supply frequency.

In our case the supply frequency is 50Hz. The other two things you should determine Output voltage which you want. The output current here I write 12V. Because 1.6 volts will be drooped at the bridge rectifier and 10.4V will remain.

The remaining 5.4 volts will drop in the LM7805 regulator and at the end constant 5 volts DC will come from the regulator.

Here are the general formulas of Resistance and Capacitor

Load = 12v,

I = 100mA (0.1A)

π = 3.1415

Vin = 230V ac

Frequency (F) = 50Hz

How to find the value of R (Xc) and Dropper Capacitor,

R = Vin - Vout (Load) ÷ I

R = 230 – 12 ÷ 0.100 = 218 ÷ 0.100 = 2180

C = 1 ÷ 2 * π * F * Xc

I = 230 – 12 ÷ 2180 = 0.1A

I hope you understand, how to a simple 230Vac to 5Vdc transformerless Power Supply design?

Post a Comment


The guide you have made is very understandable and the scheme looks detailed so even such a beginner in electronics as me can understand it.
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