In this project, we will make a DC 5V power supply using a 7805 Voltage Regulator integrated circuit, which can convert the inputs mains 220V a.c. to d.c. fixed positive 5V output. This power supply is used to turn on an LED light, run a DC Motor, Power an Arduino board, charge your Electronics device, etc. Let's make it!
Features
This power supply has Important features as follows:
- Operating Voltage is AC 220V 50 Hz
- IC 7805 is used to get the fixed-voltage output with internal Thermal Overload and Short circuit, current limiting protections
- Maximum output is DC +5V 1.5 Amp.
- Maximum power dissipation is 10.5 Watts.
- Few Components are used.
Components List
To make this 5V power supply, the following components are required:
| SL. No. | Name | Value | Quantity |
|---|---|---|---|
| 1 | T1: Center-Tapped Transformer | 12V-0-12V, 1.5A | 1 pcs |
| 2 | D1, D2: Diode | 1N4007 | 2 pcs |
| 3 | C1: Electrolyte Capacitor | 2200uF, 25V | 1 pcs |
| 4 | D3: LED | 3mm, Red Color | 1 pcs |
| 5 | R1: Resistor | 1K Ohm, 1/4W | 1 pcs |
| 6 | C2: Ceramic Capacitor | 330nF | 1 pcs |
| 7 | U1: Voltage Regulator | 7805 IC | 1 pcs |
| 8 | C3: Ceramic Capacitor | 100nF | 1 pcs |
| 9 | Connectors | 2-Pin, 3-Pin | 1 pcs, 1 pcs |
| 10 | Aluminium Heat-Sink | TO-220 | 1 pcs |
| 11 | Breadboard | - | 1 pcs |
| 12 | Connecting Wires | - | - |
Circuit Diagram
The schematic of a 5v power supply circuit using a 7805 voltage regulator is shown below.
Working Principle
The Voltage Regulator 7805 based 5V power supply circuit is an AC-to-DC supply, and the working principle is simple.
When the circuit gets input voltage from the mains 220V a.c., the centre-tapped transformer (T1) primary winding step-down the voltage to a.c. 12v-0-12v in the secondary winding. Next, the voltage is rectified by the two diodes (D1, D2) and converted to DC full-wave rectifier voltage. A LED (D3) and resistor (R1) series connection is parallelly connected with the rectifier output to indicate the input AC voltage is successfully converted to DC voltage. This voltage charges the capacitor (C1) and supplies current to the Voltage regulator (U1). Therefore, the unregulated DC voltage flow through the Voltage regulator (U1), which is regulated to give a DC positive 5V output, Extra voltage conversion in heat (a suitable aluminium heat sink recommended). Here, capacitors (C2, C3) are used parallelly with the regulator for reducing ripple noise. Thus, we will get a fixed 5V power supply.
IC 7805 Pinout Configuration
The pinout configuration of the 7805 IC is as follows:
| Pin Number | Pin Name | Description |
|---|---|---|
| 1 | Input (VIN) | Unregulated Input Voltage |
| 2 | Ground (GND) | Connected to Ground |
| 3 | Output (VOUT) | Regulated Output Voltage |
Complete Circuit
I simply assembled the circuit on a breadboard, transformer primary terminals are connected to Phase & Neutral of the Mains 220V AC supply, and the secondary terminals of the transformer are connected to the 3-pin connector.
Demo and Testing
For testing the circuit, I used a 12V 1.5A centre-tapped transformer. The capacitor C1 calculated value is 2200uF 25V. So, if you want to replace the transformer with a different rated value, the C1 value should be changed. Here are some pre-calculated capacitor values for various rating center-tapped transformers.
| For Transformer | Capacitor (C1) Value |
|---|---|
| 9-0-9V, 500A | 1500uF, 16V |
| 9-0-9V, 1A | 3300uF, 16V |
| 9-0-9V, 1.5A | 4700uF, 16V |
| 12-0-12V, 500A | 1000uF, 25V |
| 12-0-12V, 1A | 1500uF, 25V |
In this demo video, you will see the testing of the 5V Power Supply using a 7805 Voltage Regulator.
Here, I simply powered the circuit with a 220V AC source, which produces a fixed +5V, 1.5A (~approx) DC on its output.
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