Adjustable Power Supply MOSFET Control 0-220V
Build a 0-220V adjustable power supply without a transformer using MOSFET control. Complete DIY guide with circuit diagram, components, working principle, assembly steps, and safety precautions for AC load control.
Introduction to Transformerless MOSFET Power Supplies
Transformerless power supplies use capacitive or resistive droppers or MOSFET phase control to reduce AC mains voltage. The MOSFET acts as a fast electronic switch, controlling conduction duration or PWM duty cycle to regulate AC voltage output. Such designs are compact, low-cost, and efficient, suitable for dimmers, motor speed controllers, or low-power AC voltage adjustment projects.
adjustable power supply
An adjustable power supply without a transformer using MOSFET control allows precise AC voltage adjustment from 0 to 220V for powering household appliances and electronics. Unlike traditional transformer-based PSUs, this design is compact, lightweight and efficient, using a high-voltage MOSFET as the main controlling element. The MOSFET operates as a switch in a phase-controlled manner, allowing smooth voltage adjustment via a potentiometer or PWM controller. This type of transformerless power supply is ideal for low-power AC loads and small DIY experiments, providing flexibility in voltage control without bulky transformers. In this guide, we cover the required components, working principle, circuit diagram, assembly, testing, and safety precautions for building a reliable 0-220V adjustable AC power supply using MOSFET control.
Features of 0-220V MOSFET Adjustable PSU
Wide Voltage Control Range
- Output adjustable from 0V to 220V AC.
- Smooth and continuous voltage variation for different AC loads.
Transformerless Compact Design
- No bulky transformer required.
- Lightweight and ideal for portable projects.
High Efficiency and Fast Response
- MOSFET switching reduces power loss.
- Fast response allows accurate control of AC load voltage.
Components Required
High Voltage MOSFET (e.g., IRF840)
- Controls AC voltage applied to the load.
- Requires proper heatsinking to dissipate power.
Triac or Opto-Isolated MOSFET Driver
- Provides safe gate drive and isolation.
- Ensures MOSFET switching at correct timing.
Resistors and Capacitors
- RC network for gate triggering or PWM frequency adjustment.
- Snubber capacitor reduces voltage spikes across MOSFET.
Diodes and Snubber Network
- Protects MOSFET from reverse voltage.
- Reduces EMI and voltage transients.
Heat Sink and Cooling
- High-power MOSFET generates heat.
- Active cooling (fan) recommended for prolonged operation.
Working Principle
MOSFET as AC Voltage Controller
- MOSFET switches AC mains at high speed to control RMS voltage.
- Acts like an electronic variable resistor in series with the load.
Phase Control and PWM Adjustment
- Phase control adjusts conduction time in each AC cycle.
- PWM mode adjusts duty cycle, controlling effective AC voltage.
Feedback and Protection Circuit
- Optional feedback maintains stable voltage under load changes.
- Current limiting and overvoltage protection prevent damage.
Circuit Diagram and Assembly Steps
AC Input Connections
- Connect live and neutral to input terminals via a fuse.
- Ensure insulation and safe wiring practices.
MOSFET Driver Setup
- The Driver circuit isolates the microcontroller or potentiometer from high AC voltage.
- Gate connected via resistor to prevent overshoot.
Adjustable Control Potentiometer
- Controls conduction angle or PWM duty cycle.
- Allows smooth voltage variation from 0V to 220V.
Testing and Load Connection
- Start with no load, measure voltage output.
- Connect resistive load for initial testing.
- Gradually adjust the potentiometer and observe the AC load voltage.
- Monitor MOSFET temperature, add heatsink/fan if required.
Applications
- AC voltage regulator for lamps or heaters
- Motor speed control (low-power AC motors)
- Laboratory AC voltage adjustment
- DIY electronics experimentation and testing
Safety Precautions
- High-voltage AC is dangerous; take extreme caution.
- Use proper insulation, fuses, and isolation techniques.
- Do not touch the circuit when powered.
- Heat sink MOSFETs properly to prevent overheating.
- Avoid inductive loads unless the circuit is rated for them.
Troubleshooting and Maintenance
- No output: Verify MOSFET orientation and driver connections.
- MOSFET overheating: Check snubber network and add active cooling.
- Voltage not adjustable: Verify potentiometer and RC network.
- Load flickering: Ensure proper MOSFET gate triggering and snubber capacitor.
Frequently Asked Questions - Adjustable Power Supply MOSFET Control 0-220V:
What is a transformerless MOSFET power supply?
A power supply that controls AC voltage using MOSFET switching without a bulky transformer.
Can it control 0-220V AC?
Yes, it can adjust AC voltage smoothly across the full range.
Is it safe for beginners?
No, high-voltage AC is dangerous; only experienced users should attempt.
Which MOSFET is used?
High-voltage MOSFETs like IRF840 or equivalent.
Do I need a heatsink?
Yes, the MOSFET can get very hot at high AC voltage and current.
Can it drive AC motors?
Yes, small AC motors within current rating can be controlled.
Is potentiometer used?
Yes, it adjusts conduction angle or PWM duty cycle for voltage control.
What is the role of snubber network?
Protects MOSFET from voltage spikes and reduces EMI.
Can I use it for lamps or heaters?
Yes, ideal for resistive AC loads like lamps or heaters.
Does it require isolation?
Yes, driver circuit should isolate low-voltage control from AC mains.
