Need a strong 12V DC supply for our electronics projects?
A stable and powerful DC supply is the heart of any electronics project.
This Transformer Based 12V DC 3A Power Supply Circuit delivers clean and reliable power.
It converts AC mains into smooth DC power and it provides high current with low noise output.
It is simple to build and uses easily available components.
Perfect for hobbyists, students and DIY electronics lovers.
Circuit Working:

Parts List:
| Components Name | Specification | Quantity |
|---|---|---|
| Resistor | 1.2k 1/4 watt | 1 |
| Capacitors | Electrolytic 2200uF 25V | 4 |
| Ceramic 0.1uF | 1 | |
| Bridge Rectifier 6A 100V | 1 | |
| LED any 5mm | 1 | |
| Step-Down Transformer 12V, 3A Secondary, 220V AC Primary | 1 | |
| ON/OFF Switch SPST | 1 | |
| Fuse 1A | 1 |
In this article transformer reduces high AC voltage to 12V AC.
Bridge rectifier changes AC into pulsating DC.
Capacitors C1 to C4 make the DC more smooth and capacitor C5 removes small high frequency noise.
LED turns ON when DC power is available and DC output is taken from capacitor positive and ground terminals.
How to Build:
To build a Transformer Based 12V DC 3A Power Supply Circuit following are the steps we need to follow:
- Gather all the parts as shown in circuit diagram.
- Transformer primary pins connect to AC mains via switch and fuse.
- Transformer secondary pins connect to bridge rectifier AC pins.
- Bridge rectifier positive pin connects to capacitor positive rails.
- Bridge rectifier negative pin connects to ground line.
- All capacitor positive pins connect together at the output.
- All capacitor negative pins connect to ground.
- LED anode connects to output through resistor R1.
- LED cathode connects to ground.
Conclusion:
This Transformer Based 12V DC 3A Power Supply Circuit is simple and effective.
It uses easily available components and provides high current DC output.
It is best for non-sensitive electronics and by adding a regulator we can improve voltage stability.
References:
What is the circuit diagram of a 12V DC power supply and explain its functions?
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