Switch mode power supply:
pros:
- high efficiency,
- easy to create and adjust the wide range of output voltage/current.
- light weight.
cons:
- big noise/interference. Not suitable for analog circuits if lack of other measures.
- output voltage is not really clean, lots of spikes, hums, ... with a large frequency range.
- hard to build, repair.
- expensive.
Linear power supply:
pros:
- output voltage/current are very clean. This is very suitable for analog circuit.
- easy to build, easy to adjust, easy to repair.
- low noise/interference.
- cheap.
cons:
- heavy.
- low efficiency.
- not easy to change the output voltage/current.
As you see, nowadays, digital electronics become very popular, so this is the era for the switch mode power supply. jaya000 is right, for example, analog audio system is now still the best over the digital, you cannot find out any switch mode power supply in the high quality audio system but still see the big heavy transformer there.
nguyennam