Are you converting high voltage DC to 12V DC using LM7812 voltage regulator IC? im also doing this method in past days but one problem is their the output current. The LM7812 voltage regulator IC can only deliver upto 1A current. In most of the power electronic circuits or motors needs 2 to 8A current, so i decided to build simple circuit to get 12V 8A linear current using LM2940 voltage regulator IC and three TIP2955 PNP transistor. The circuit diagram and working principle also sharing with you.
Components List
| Component | Designator(s) | Quantity |
|---|---|---|
| 3300µF / 35V Capacitor | C1 | 1 |
| 0.47µF / 63V Capacitor | C2 | 1 |
| 100µF / 35V Capacitor | C4 | 1 |
| KBP410 Bridge Rectifier | D1 | 1 |
| 2.54mm Male Header | J1, J2, J3, J4 | 4 |
| Green LED | LED1 | 1 |
| TIP2955 PNP Transistor | Q1, Q2, Q3 | 3 |
| 15Ω 10W Resistor | R1 | 1 |
| 1kΩ Resistor | R2 | 1 |
| 0.1Ω 10W Resistor | R3, R4, R5 | 3 |
| LM2940 Voltage Regulator | U1 | 1 |
| STPS1545FP Schottky Diode | U2 | 1 |
Circuit Diagram
Construction and Working Principle
In this circuit you can use a step down transformer with voltage between 12 to 26V and 8A current, which is connected through the input terminal. The KBP410 bridge rectifier converts the AC input to pulsating DC voltage. The large electrolytic capacitor C1 of 3300uf will smooths the pulsating DC voltage to reduce ripple in voltage.
The Resistor R1 15Ω 10W limits the inrush current and helps with initial load handling for the LM2940. The LM2940 is a low dropout regulator and it will provides a stable 12V DC output, but only up to around 1A on its own.
The three TIP2955 PNP power transistors are connected in parallel to boost the current capacity up to 8A. The Emitter pin connected resistors of R3, R4, R5 ensure an equal current sharing among the transistors.
The capacitors C2 and C4 help to stabilize the regulator and smooth the final output. The LED1 is lights up to indicate the power is ON. The 1kΩ resistor will limits current to the LED. In final output section The circuit delivers a clean, regulated 12V DC output at up to 8A current.
Applications of the 12V 8A Linear Power Supply Circuit
- DIY audio amplifier projects.
- 12V LED strip lighting setups.
- Arduino, Raspberry Pi, and other microcontroller projects with higher current needs
- Battery charging circuits.
- Bench power supply for electronics testing.
- Car audio systems or accessories requiring regulated 12V.
