Circuits
Power Supplies (5)
- A transformer operating at 50Hz can be bulky and heavy;
Power Supply Unit (PSU) can be inefficient;
ripple needs large capacitors to filter
- The switched mode power supply does this.
The mains drives an oscillator or chopper directly (not isolated)
to generate a voltage at 50-200kHz.
This is then transformed to near required voltage by a much smaller,
lighter transformer, (smaller core useable at higher frequency)
rectified, smoothed by smaller value components
- Efficient but Electrically noisy, can give EMC (ElectroMagnetic Compatability)
problems due to switching/oscillator harmonics if not properly shielded