• Skip to main content
  • Skip to primary sidebar

Making Easy Circuits

Learn and build electronic circuits

You are here: Home / Power supply / How to Build a Simple SMPS Circuit

How to Build a Simple SMPS Circuit

Last Updated on November 17, 2024 by Admin Leave a Comment

Due to significant interest in this particular design, a simple non-regulated switching symmetric power supply with a high power output of 350W has been developed.

It employs a Half Bridge configuration without regulation.

This power supply serves as an alternative to standard power supplies used in audio amplifiers, as traditional transformers and electrolytic capacitors for power amplifiers tend to be costly and bulky.

Moreover, transformers are unsuitable for portable devices due to their weight. However, it should be noted that this simplicity comes at a cost, as a short circuit or overload can damage the MOSFETs and other components.

Additionally, MOSFETs may experience stress during power-up as they need to charge the output capacitors.

Circuit Description

simplest SMPS circuit

This very simple switch mode power supply circuit utilizes two N MOSFETs, driven by the integrated circuit IR2153.

Although this switching power supply lacks stabilization, it still provides a more stable and less noisy output voltage compared to a typical power supply, making it suitable for audio amplifiers.

The ripple at full load is less than 2V. To power the IR2153 circuit, a 27k 6W power resistor is employed. The built-in 15V Zener diode ensures voltage stabilization.

The operating frequency of the power supply is approximately 50kHz. To limit the peak current during capacitor charging, a thermistor is included at the input.

This thermistor can be salvaged from a faulty AT or ATX PC power supply. The transformer core is also sourced from any PC power supply.

Winding the Transformer

When winding the transformer, the primary winding is done first with 20 turns, followed by the secondary windings, and finally completing the rest of the primary winding.

This winding method minimizes leakage inductance, resulting in a more stable output voltage.

Adequate insulation must be maintained between the primary and secondary windings for safety reasons.

For increased safety, it is recommended to connect the output (i.e., center tap 0V) to the earth ground.

Chokes are incorporated to attenuate RF output ripple from the power supply.

The number of turns in the chokes is not critical, and various cores can be used, including those salvaged from PC power supplies.

To discharge the capacitors after switching off and prevent voltage spikes under no-load conditions, a 6k8 resistor is connected to the output.

Optionally, an LED can be connected in series with the resistor. The MOSFETs are mounted on a small heatsink, such as one sourced from a PC power supply, to dissipate heat effectively.

You'll also like:

  • 1.  High Current Voltage Regulator Circuit
  • 2.  Add this Adjustable Current Circuit to your Power Supply
  • 3.  Simple Power Supply Circuits Explained
  • 4.  How to Build a LM317 as a Variable Voltage Regulator and Variable Current Regulator
  • 5.  1A Voltage Regulator better than 7805, 7812
  • 6.  How to Calculate Capacitor Current in Transformerless Power Supplies

About Admin

Hey friends, Thanks a bunch for stopping by this site! I am an engineer with a Bachelor of Engineering in Electronics and Telecommunication. One of my passions is gathering information from all sorts of electronics books and tutorials. I then take that information and compile it into a language that is super easy to understand. My goal is to make those complex electronics circuit concepts and technical terms much more accessible for all the new and budding electronics engineers out there. I can also design customized circuit diagrams as required by the users.
If you have any questions related to this field, please do not hesitate to drop a comment! I am always here and ready to help you out with any queries you might have. I cannot wait to hear from you!

Reader Interactions

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Primary Sidebar

Categories

  • 3 Phase (4)
  • 8051 Microcontroller (1)
  • Arduino (11)
  • Audio and Amplifier (102)
  • Automation (8)
  • Battery Chargers (64)
  • Bicycle Projects (4)
  • Car and Motorcycle Projects (39)
  • Datasheets (10)
  • DIY Projects (5)
  • Electrical (15)
  • Free Energy (6)
  • Games Projects (2)
  • High Voltage (14)
  • Hobby Projects (30)
  • Household Circuits (2)
  • IC 555 Circuits (5)
  • Ignition Circuits (2)
  • Indicators (50)
  • Infrared (6)
  • Inverter Circuits (29)
  • Lights and Lamps (97)
  • Medical (8)
  • Meter and Tester Circuits (38)
  • Motor Driver (17)
  • New Circuits (56)
  • Oscillators (30)
  • Pets and Pests (5)
  • Power supply (80)
  • Protection Circuits (25)
  • PWM (9)
  • Remote Control (20)
  • Security and Alarm Circuit (48)
  • Sensors and Detectors (66)
  • Signal Processor (23)
  • Solar Controller Circuits (62)
  • SSR (3)
  • Temperature Controller (20)
  • Timer (25)
  • Transformerless (7)
  • Transmitters (12)
  • Tutorials (45)
  • UPS (2)
  • Voltage Regulators (57)
  • Water Sensor and Controller (29)
  • Home
  • Privacy Policy
  • Contact
  • Disclaimer
  • Copyright

© 2025 · Making Easy Circuits