Last Updated on March 16, 2024
Most Electronic Components and Microcontrollers requires 5V DC power supply to operate smoothly, Arduino and Raspberry Pi projects are operate on a 5V supply. USB, Digital circuits and ICs also commonly use 5V. Maximum Current consumption of these elements are lies between few milliamps (mA) to 2 Amps. Some applications requires different voltages like 24V, 12V and 5V DC supply, in such case only one Single Stepdown transformer is used and step-downed to maximum required AC supply (24VAC) then Rectified to DC after that Voltage Regulators LM78XX series used to to get desired Voltage levels. You may think about Reducing the voltage by using Resistors but it is possible to draw more voltage and current by the load components and leads to thermal runaway to avoid that and to provide constant Voltage and load balance we use Voltage Regulators.
Following 12V to 5V Converter Circuit using LM7805 IC from Texas Instruments, IC 7805 is a three terminal positive voltage regulator, it can provide output current up to 1.5 A, It has internal thermal overload protection. IC LM7805 has high power dissipation capability and internal short circuit current limiting. This type of voltage regulator has wide range of applications. The “78” in the series indicates that the regulator provides a positive voltage output. In 79XX series Voltage Regulators “79” indicates Negative Voltage Output.
LM7805 Pinout
This IC is being used in different categories of applications like, DC Supply Adapters, SMPS, Industrial Power supply unit, Electronic equipment and devices, Inverters etc..,
Circuit Diagram
12V to 5V Converter Circuit using LM7805 with LED Indicators
AC to DC 5V Regulated Power supply Circuit
Components List
| S.No | Designator | Value | Part Number | Quantity |
| 1 | TR1 | 230V to 0-12V AC | 0-12V Stepdown Transformer | 1 |
| 2 | R1, R2 | 330Ω | – | 2 |
| 3 | C1 C2 | 100µF/25V 0.01µF | Electrolytic Disc capacitor | 1 1 |
| 4 | D1 | – | Bridge Rectifier Module | 1 |
| 5 | U1 | LM7805 | LM7805_TO220 | 1 |
| 6 | LED1 LED2 | Red Green | – – | 1 1 |
Construction & Working
IC 7805 Can be employed in any kind of PCB board and prototype because of its different types of packages. Lets start with Construction of 5V DC Regulator. When there is 12V to 35V DC supply available and you need 5V from it then you can blindfoldly use Positive Voltage Regulator 7805 (maximum current limit 1.5A). This IC have only three pins, First one is for input and 2 is for Gnd and 3 for output. Connect the IC 7805 with appropriate capacitors for input and output stabilization. Additionally, heat sinks are often employed to dissipate excess heat generated during the voltage regulation process.
All the three circuits are doing the same operation, First circuit is used to employed in between 12V DC and component that requires 5V DC. Second Circuit is used where the Voltage Presence indication is crucial. Third one is AC to DC 5V Regulated Power supply Circuit which can be used as independent 5V DC power source.