Transformerless Power Supply – 220V AC to 9V DC

Overview: Transformerless Power Supply
In this project, we will
design Transformerless Power Supply
for
low current
applications. Basically a
transformerless power supply
is just a voltage divider network that takes the
220V AC
as input and divides it down to Lower DC voltage that we want. The AC voltage need is rectified through a few diodes and regulated to a maximum voltage. Earlier we learnt about
Dc-DC Converter circuit
. But now we will convert the
AC to DC
Transformerless Power Supply is especially inexpensive products where the cost of a
transformer
is removed. Transformers are bulky and expensive. Most of the electrical appliances used in our daily life like LED light, Lamp, Laptop &
Phone Battery Chargers
, Hair Drier, Toys, etc work at lower DC voltage like 5V, 9V, 12V, or 15V. So we need to lower down the 220V or 110V AC to lower DC without making the circuit bulky and keeping the PCB size small.
To power low current demanding logic circuits and microprocessor circuits, the
transformerless power supply
is an ideal solution.
Bill of Materials
Following are the components required for making this project. All the components can be easily purchased from Amazon.
S.N.
Components
Description
Quantity

Resistor
470 Ω

Resistor
470 K Ω

Capacitor
0.47 µF, 450V (Electrolytic Capacitor)

Capacitor
470 µF, 25V (Electrolytic Capacitor)

1N4007
Rectifier Diode

1N4739A
Rectifier Diode

Design considerations
There are two types of transformerless power supplies that are
Capacitive
&
Resistive
. Capacitive type is more efficient compared to Resistive Type because of the
low heat dissipation
and
very low power loss
. If a circuit requires a very low current of a
few milliamperes
, such power supply is an ideal solution.
Before designing a power supply, we need to go through some
design considerations
. If a non-polarised capacitor and a resistor are kept in series with the AC power line, a constant current can be maintained through the resistor. In this case, the
reactance
of the capacitor should be greater than the
resistance
of the resistor used.
The current flowing through resistor R depends on the value of capacitor C. The more the
Capacitance
, the more the current to the circuit. Current flow through dropping capacitor C depends on its
reactance (X)
. The value of the current passing through the
X-Rated capacitor
is defined as:
IRMS = VIN /X
The selection of the voltage dropping capacitor is very crucial. it is based on
Reactance of Capacitor
and the amount of current to be withdrawn. The Reactance of the capacitor is given by below formula:
We have used 0.47uF capacitor and frequency of mains is 50 Hz so the Reactance X is:
X = 1 / 2
3.14

0.47
10-6 = 6.77 Kohm
Now we can calculate the current (I) in the circuit:
I = V/X = 230/6775 = 34mA
Transformerless Power Supply Circuit
We used
220V AC main
as the input voltage. You may connect fuse for safety reasons. The 220V AC is then rectified through a few
diodes
. In this circuit, we used 2 diodes
1N4007
as a
half-bridge rectifier
. Normally,
DC voltage dividers
are made with a pair of resistors. Combined, they define the current flowing through the path.
We used 9V
Zener Diode 1N4739A
to limit the voltage to 9V. If you want 5V or 12V or any other output voltage, you need the specific Zener diode according to voltage rating. You can use our
DIY Voltmeter
to measure the output voltage.
We simulated the circuit using
Proteus
Software. The simulated image is shown below.
Project PCB Gerber File & PCB Ordering Online
If you don’t want to assemble the circuit on a breadboard and you want PCB for the project, then here is the PCB for you. The PCB Board for Transformerless Power Supply is designed using
EasyEDA
online Circuit Schematics & PCB designing tool. The PCB looks something like below.
The Gerber File for the PCB is given below. You can simply download the Gerber File and order the PCB from
ALLPCB
at
1$
only.
Download Gerber File:
Transformerless Power Supply
You can use this Gerber file to order high quality PCB for this project. To do that visit the
ALLPCB
official website by clicking here:
https://www.allpcb.com/
You can now upload the Gerber File by choosing the Quote Now option. From these options, you can choose the Material Type, Dimensions, Quantity, Thickness, Solder Mask Color and other required parameters.
After filling all details, select your country and shipping method. Finally you can place the order.