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Build Your Own 24V 2A Variable DC Power Supply
Description
A versatile direct current power supply is a frequently utilized instrument for electronics enthusiasts. This circuit isn't a recent innovation; it’s straightforward, dependable, durable, and resistant to short circuits, offering adjustable voltage up to 24V and adjustable current limiting up to 2A. Modifications can be made to suit individual specifications, as detailed within the following documentation.Circuit Diagram :
Parts:
- R1 = 500Ω
- R2 = 10kΩ
- R3 = 2.2kΩ - 1/2W
- R4 = 2.2kΩ - 1/2W
- R5 = 330Ω
- R6 = 150Ω
- R7 = 1Ω - 5W
- C1 = 35V - 3300µF
- D1 = 1N5402
- D2 = 1N5402
- D3 = 5mm Red LED
- C2 = 63V - 1µF
- Q1 = BC182
- Q2 = BD139
- Q3 = BC212
- Q4 = 2N3055
- SW1 = SPST Mains Switch
- T1 = 36VCT - Transformer
Notes:
- R1 determines the maximum current output that will be delivered by the supply at a given voltage level.
- R2 establishes the output voltage, and it should be a logarithmic taper type to ensure a more linear representation of the voltage scale.
- The selection of the Transformer can be based on the required maximum voltage and current output. Suitable options include 36, 40, or 48V center-tapped and 50, 75, 80, or 100VA.
- Capacitor C1 can be chosen within the range of 2200 to 6800µF, with a voltage rating of 35 to 50V.
- Transistor Q4 must be mounted on an adequate heatsink to withstand prolonged short-circuit conditions. The rear panel of the metal enclosure used to house the circuit can often perform this function.
- The 2N3055 transistor (Q4) can be swapped out with a TIP3055-type device.
Integrated Circuits (ICs) Details
Several integrated circuits play crucial roles within this power supply design. Understanding their function and characteristics is essential for proper operation and troubleshooting.The BC182 (Q1), a general-purpose NPN bipolar junction transistor, serves as a current amplifier and switching element. This transistor facilitates the amplification of current signals and provides a switching function within the circuit. Its characteristics include a moderate gain and relatively low saturation voltage, making it suitable for a range of applications. The BC182's moderate gain and low saturation voltage are key factors in its performance within this circuit.
The BD139 (Q2) is a high-current NPN BJT often employed in switching applications. Its robust design and ability to handle significant currents make it ideal for switching tasks within this power supply. The BD139 is frequently selected for its high current capability, enabling it to handle the demands of switching operations effectively.
The BC212 (Q3) is another general-purpose NPN BJT, offering similar characteristics to the BC182 and BD139. It provides amplification and switching capabilities, contributing to the overall functionality of the power supply. This transistor’s moderate gain and switching abilities make it a valuable component within the circuit.
The 2N3055 (Q4) is a widely used NPN Bipolar Junction Transistor offering a combination of performance and availability. It’s frequently utilized in switching and amplification circuits. The 2N3055 is valued for its dependability and adaptability, frequently serving as a reliable switching element in this design.