How to Use a DC Power Supply: A Complete Guide for Engineers and Technicians

Introduction

A DC power supply is an essential tool for electronics testing, circuit design, and troubleshooting. Whether you're a beginner or an experienced engineer, understanding how to use a programmable, variable, or bench DC power supply effectively is crucial for ensuring accurate results and protecting your devices.

In this guide, we’ll cover the basics of DC power supplies, step-by-step instructions on setup and operation, and examples of Tektronix power supplies to help you choose the right one for your application.

What is a DC Power Supply?

A DC power supply converts AC (alternating current) from the mains into a stable DC (direct current) output. It provides a controlled voltage and current to power electronic circuits and test components.

Types of DC Power Supplies

• Linear Power Supplies – Low-noise operation, ideal for precision applications.
• Switching Power Supplies – More efficient and compact, suitable for high-power applications.
• Programmable Power Supplies – Allow for voltage and current adjustments via software or manual input.
• Bench Power Supplies – Designed for lab and R&D environments, featuring easy-to-use interfaces.
• Variable Power Supplies – Provide adjustable output voltage and current, suitable for testing and development purposes.
• Lab Power Supplies – Specifically designed for laboratory settings, offering precise control and measurement capabilities.
• High Current Power Supplies – Capable of delivering large currents, used in applications requiring significant power.
• High Voltage Power Supplies – Provide high voltage outputs, essential for applications like electron beam and X-ray systems.
• High Power Power Supplies – Designed to deliver both high voltage and high current, used in industrial and research applications.
• ATE (Automated Test Equipment) Power Supplies – Integrated into automated testing systems, offering programmable features and remote control capabilities.
• Autoranging Power Supplies – Automatically adjust the voltage and current range to maximize output power, providing flexibility for various load conditions.

How to Use a DC Power Supply: Step-by-Step Guide

1. Choose the Right Power Supply

   Select a power supply that meets your voltage and current requirements. Consider models like:

   • Keithley 2231A-30-3 – A triple-output programmable power supply for lab applications.
   • Keithley 2260B Series – High-power programmable DC power supplies with advanced control features.
   • EA Bidirectional Power Supplies – High-voltage and high-current power supplies for industrial applications.
   • Read more about how to choose a benchtop power supply.

2. Understand Power Supply Controls

   Most DC power supplies include the following controls:

   • Voltage Adjustment: Sets the desired output voltage.
   • Current Limit Adjustment: Protects your circuit by capping current output.
   • Output Terminals: Red (positive) and black (negative) terminals for connecting to your circuit.
   • Display & Interface: Provides real-time voltage, current, and power readings.
   

   DC Power Supply Front Panel Details (See image above and corresponding numbers below)

   (1) Display

   The display shows information.

   (2) Information

   During operation, the display provides information about the output (top row) and settings (bottom

   row) for volts (left column) and current (right column). During configuration, the display shows the

   configuration menus (bottom row).

   (3) Arrow keys

   Up, down, right, and left arrow keys (▲ and ▼) and Enter key.

   (4) Navigation wheel

   Rotate the navigation wheel to increase or decrease digits or to select menu items.

   (5) Output connectors

   Three banana jack output connectors provide high, low, and chassis ground connections.

   (6) Save and recall keys

   See Key descriptions (on page 2-7) for descriptions of these keys.

   (7) Numeric keypad

   The numeric keypad provides number keys (0 to 9 and Esc) for direct numeric entry.

   (8) V-Set, I-Set, Shift, and Output On/Off keys

   See Key descriptions (on page 2-7) for descriptions of these keys.

   (9) Power switch

   Press the power switch to turn the instrument on (|). Press it again to turn the instrument off (0)

3. Connect the Load Properly

   • Turn off the power supply before making connections.
     • Use the correct wiring:Red (+) terminal connects to the positive side of your circuit.
     • Black (−) terminal connects to the ground or negative side.
   • Ensure proper wire gauge to handle the expected current.

4. Set Voltage and Current Limits

   • Adjust the voltage to the required level for your circuit.
   • Set a current limit slightly above the expected operating current to prevent overloading.
   • Many Tektronix power supplies feature constant voltage (CV) and constant current (CC) modes to protect sensitive components.

5. Turn on the Power Supply and Monitor Output

   • Power on the supply and check the display for accurate voltage and current readings.
   • Use a digital multimeter (e.g., Keithley DMM6500) to verify the output voltage at the load.

6. Adjust as Needed and Power Down Safely

   • If the circuit requires adjustments, fine-tune the voltage or current settings.
   • Always turn off the power supply before disconnecting the load to avoid sparks or damage.

Common Mistakes to Avoid

• Setting the voltage too high – Can damage sensitive components.
• Not setting a current limit – May result in excessive current draw and overheating.
• Reversing polarity – Incorrect connections can lead to circuit damage.
• Ignoring ground loops – Can cause noise and measurement errors in sensitive applications.

Applications of DC Power Supplies

• Electronics Testing & Debugging – Powers circuit prototypes and PCBs.
• Battery Charging & Simulation – Used in EV and renewable energy applications.
• Industrial & Research Labs – Provides stable DC power for scientific experiments.
• Semiconductor Device Testing – Ensures accurate performance measurements.

Power Supply Measurement Tips

Check out each page below in a 10-part series or download as a PDF brochure:

Part 1: Component Selection and Characterization for Power Supply Design

Part 2: Low-Voltage DC Circuit Power-On Test

Part 3: High-Voltage AC Circuit Power-On Test

Part 4: Digital and Analog Control Circuit Debug

Part 5: Testing Power Stage Switching Characteristics

Part 6: Switching and Conduction Loss Testing

Part 7: Power Supply Specification Check

Part 8: Power Line Compliance Testing

Part 9: EMI Troubleshooting and Pre-compliance

Part 10: Design Validation

Conclusion

Using a DC power supply correctly is essential for safe and reliable electronics testing. By following proper setup procedures, selecting the right model, and monitoring your power output, you can prevent damage to your components and achieve precise results.

Tektronix offers a wide range of programmable and bench DC power supplies to meet various needs. Explore our full lineup to find the right solution for your application.