Introduction:
If we look around the world today, electrical and electronics equipment occupy the major space in our lives. Every electronic equipment needs power to operate and here comes the use of a power supply. A power supply is an electrical device that provides power to the load, it converts the electric current from the source into the required current, voltage, and frequency to derive the load. It is divided into different categories.
This post is a brief explanation of a dual power supply and its types. A dual power supply provides two distinct DC (positive and negative) output voltages. It ensures the stability of the supply and helps to prevent damage to the system. It has many applications in our day-to-day life.
The three main types of dual power supply include:
- 5V Dual Power Supply
- 12V Dual Power Supply
- 15V Dual Power Supply
Hardware Components:
The following components are required to make Dual Power Supply Circuits
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | Step down Transformer | 6 or 15 or 20V AC | 3 |
| 2. | Bridge Rectifier/ Diodes | 1N4007 | 12 |
| 3. | Electrolyte Capacitor | 1000uF, 10uF & 0.1uF | 6, 6, 6 |
| 4. | Regulator IC | 7805, 7812, 7815, 7905, 7912, 7915 | 1 |
7805 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of 7805
7812 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet 7812
7815 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of 7815
Dual Power Supply Circuits
Working Explanation:
For the given circuit diagrams above, the working principle is similar, but the values of components vary according to the output supply voltage range. The basic circuit contains a transformer, rectifier, regulator ICs and capacitors.
The center-tapped transformer steps down the 230V AC source to the desired AC voltage splitting it into two halves, which then is rectified and converted into a DC signal using a bridge rectifier. The capacitors C1 and C2 are responsible for the filtration of the DC signal, C1 filters the positive side while C2 filters the negative side of the signal. The DC unregulated signal is then passed through the voltage regulators, the 78XX regulator is used for the positive component of the signal while the 79XX is used for the negative component.
The capacitors C3 and C4 then eliminate the ripples from the DC signal and the high-frequency ripples are removed using the capacitors C5 and C6. The ground terminal is provided from the center-tapped transformer directly to the positive and negative supply outputs.
Uses of Dual Power Supply:
The applications of dual power supply are as follows:
- It is used in the Op-amp circuits as the op-amp needs a positive and a negative supply.
- The school laboratories mostly utilize a dual power supply as a bench supply.
- The dual power supplies are needed to operate generators.
- They are also used in various DIY projects like cell phone chargers, power banks, etc.
