In this tutorial, we are going to make a “12v and 5v Dual Power Supply”.
A regulated power supply is an embedded circuit; it converts unregulated AC (Alternating Current) into a constant DC. This is a simple approach to obtaining a 12V and 5V DC power supply using a single circuit, such a circuit is very useful in cases when we need two DC voltages for the operation of a circuit.
We designed a basic 12v and 5v Dual Power Supply with easily available components. Here we have a 1 Amp step-down transformer you can use up to your specifications and need two LEDs to indicate the output power supply for both 12V and 5V.
Hardware Components
The following components are required to make a Dual Power Supply Circuit
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | Step down transformer | 0-15V AC | 1 |
| 2. | Resistor | 2KΩ, 1KΩ | 1,1 |
| 3. | Diode | 1N4007 | 4 |
| 4. | IC | L7812, L7805 | 1 |
| 5. | Power Supply | – | 1 |
| 6. | Electrolyte Capacitor | 1000µF, 100µF | 1, 1 |
| 7. | LED | 5mm | 2 |
| 8. | Ceramic Capacitors | 0.1µF | 2 |
L7805 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of L7805
L7812 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of L7812
Dual Power Supply Circuit
Working Explanation
As we can see in the circuit, the first step in this is to step down the input AC power supply. The input of any power is 230V AC; to step down, we use a step-down transformer. This transformer steps down the 230V AC up to 5V AC. Now we want DC voltage; the rectifier circuit does this task. So, a step-downed AC supply is directly applied to the Bridge Rectifier module, here the AC supply is converted into a DC supply.
Once we got DC voltage does not mean the task is complete. To get stabilized DC voltage, we need a filter circuit. The output DC supply from the Bridge Rectifier module will have AC ripples and some voltage fluctuations as appear in the input AC supply. The filtering task is done by the capacitors used in the circuit. Capacitors help us to reduce ripples, so DC supply from Bridge rectifier is applied to Filter capacitor C1 here most AC ripples are removed and thus the filtering gets completed.
Now the main and the last task is voltage regulation. To complete this task, we use a voltage regulator IC L7812. IC L7812 Regulated input unregulated DC and gives Regulated 12 V DC at output pin then C2 capacitor performs high-frequency ripple filtering. Output 12 V is taken from this point. LED 1 indicates the 12V DC supply presence.
12 Volt DC is again filtered by C3 capacitor and then regulated by IC L7805 regulator, at the output of 7805 we can obtain a 5 Volt Regulated supply. Capacitor C4 performs high-frequency AC ripple filtering and LED 2 indicates the presence of 5V output. Common Ground (GND) is used for both 12 V and 5 V DC outputs.
Application
OPAMPS has two rails. So, to provide power to the OPAMPS, we need a Dual power supply.
When we want to run two different power circuits on the same power supply without taking it offline, we need a dual power supply.
we can use a dual power supply as a cell phone charging circuit, power bank circuit, in the Battery-less power circuits, also in case of any direct current power supply.
