How to Build a Power Supply Splitter Using an Op-Amp: A Step-by-Step Guide

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If you’re an electronics enthusiast or a hobbyist looking to power your circuits with both positive and negative voltages, a power supply splitter using an op-amp is a fantastic solution. This circuit can convert a single positive voltage source into a dual-rail power supply, providing both +12V and -12V outputs. In this article, we’ll dive into the workings of a power supply splitter circuit using the TL071 op-amp, break down its components, and guide you through building one yourself. Let’s get started!

What is a Power Supply Splitter?

A power supply splitter is a circuit that takes a single voltage input (like +12V) and splits it into a dual-rail output, typically providing both positive and negative voltages (e.g., +12V and -12V) with a common ground. This is particularly useful for analog circuits, audio amplifiers, or any application requiring a symmetrical power supply.

The circuit we’ll analyze uses a TL071 operational amplifier (op-amp) to achieve this. It’s a simple, cost-effective, and reliable method for creating a dual power supply without needing a separate negative voltage source.

Understanding the Circuit: Power Supply Splitter with TL071 Op-Amp

Let’s break down the circuit schematic step by step. The diagram uses a TL071 op-amp as the core component, along with a few transistors, resistors, and capacitors to stabilize and regulate the output.

Components List
  • TL071 Op-Amp (IC1): A low-noise, high-input-impedance op-amp ideal for this application.
  • Transistors:
    • 2N3055 (NPN transistor) for the positive rail.
    • MJ2955 (PNP transistor) for the negative rail.
  • Resistors:
    • Two 10kΩ resistors for setting up the voltage divider.
  • Capacitors:
    • 1000µF, 25V capacitors for filtering the output rails.
  • Diode:
    • 6A4 diode for protecting the circuit from reverse polarity.
  • Power Supply:
    • A single +12V input source.
How the Circuit Works
  1. Input Stage:
    • The circuit starts with a single +12V input, which is fed through a 6A4 diode for reverse polarity protection.
  2. Voltage Divider:
    • Two 10kΩ resistors are connected in series between the +12V and ground, creating a midpoint voltage of +6V. This midpoint acts as a virtual ground for the circuit.
  3. Op-Amp Role:
    • The TL071 op-amp is configured as a unity-gain buffer. Its non-inverting input (pin 3) is connected to the +6V midpoint, while the inverting input (pin 2) is tied to the output (pin 6) through feedback.
    • The op-amp ensures that its output (pin 6) also sits at +6V, creating a stable reference for the virtual ground.
  4. Output Stage:
    • The 2N3055 (NPN) and MJ2955 (PNP) transistors are used as emitter followers to provide current amplification.
    • The 2N3055 sources current for the +12V rail, while the MJ2955 sinks current for the -12V rail.
    • The 1000µF capacitors at the output filter out any noise, ensuring clean +12V and -12V rails relative to the virtual ground.
  5. Final Output:
    • The circuit produces +12V and -12V with respect to the virtual ground (GND), which is effectively at +6V relative to the input ground.
power supply splitter using op-amp circuit

Why Use an Op-Amp for a Power Supply Splitter?

Using an op-amp like the TL071 in a power supply splitter offers several advantages:

  • Stability: The op-amp ensures a stable virtual ground, even under varying load conditions.
  • Simplicity: The circuit requires minimal components, making it easy to build.
  • Cost-Effective: The TL071, 2N3055, and MJ2955 are affordable and widely available.
  • Versatility: This design can be adapted for other voltage levels by adjusting the input voltage and resistors.

Step-by-Step Guide to Build the Power Supply Splitter

Here’s how you can build this power supply splitter yourself:

  1. Gather Components:
    • Ensure you have all the components listed above. Double-check the ratings of the capacitors (25V) and transistors to handle the required current.
  2. Set Up the Power Supply:
    • Connect a +12V DC power source to the input. Use a 6A4 diode in series to protect against reverse polarity.
  3. Assemble the Voltage Divider:
    • Connect two 10kΩ resistors in series between the +12V line and ground. The junction of these resistors will provide the +6V virtual ground.
  4. Wire the TL071 Op-Amp:
    • Connect the TL071 as follows:
      • Pin 3 (non-inverting input) to the +6V junction.
      • Pin 2 (inverting input) to pin 6 (output) for unity-gain feedback.
      • Pin 7 to +12V .
      • Pin 4 to ground.
    • The output (pin 6) will maintain the virtual ground at +6V.
  5. Add the Transistors:
    • Connect the 2N3055 and MJ2955 transistors in an emitter-follower configuration:
      • 2N3055: Base to the op-amp output (pin 6), collector to +12V, emitter to the +12V output rail.
      • MJ2955: Base to the op-amp output (pin 6), collector to ground, emitter to the -12V output rail.
  6. Add Filtering Capacitors:
    • Place 1000µF capacitors between the +12V output and ground, and between the -12V output and ground, to filter out noise.
  7. Test the Circuit:
    • Power on the circuit and measure the outputs using a multimeter. You should see +12V and -12V relative to the virtual ground (GND).

Applications of a Power Supply Splitter

This circuit is incredibly versatile and can be used in various applications, such as:

  • Audio Amplifiers: Many audio circuits require dual power supplies for proper operation.
  • Signal Processing: Analog circuits often need symmetrical voltages for processing signals.
  • DIY Projects: Perfect for hobbyists building operational amplifier-based projects.
  • Testing Circuits: Useful for prototyping circuits that require both positive and negative voltages.

Tips for Optimizing Performance

  • Heat Sinks: The 2N3055 and MJ2955 transistors may generate heat under high current. Attach heat sinks to prevent overheating.
  • Capacitor Ratings: Ensure the capacitors are rated for at least 25V to handle the voltage swings.
  • Load Testing: Test the circuit with your intended load to ensure it can supply the required current without voltage drop.
  • Component Quality: Use high-quality components to avoid noise and ensure long-term reliability.

Conclusion

Building a power supply splitter using a TL071 op-amp is a straightforward and effective way to create a dual-rail power supply from a single voltage source. With just a handful of components, you can generate stable +12V and -12V outputs for your electronics projects. Whether you’re working on an audio amplifier, a signal processing circuit, or a DIY experiment, this circuit is a must-have in your toolkit.

Ready to get started? Grab your components, follow the steps above, and power up your next project with a reliable dual power supply! If you have any questions or need further assistance, feel free to leave a comment below.

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