buck converter/step-down converter vs resistor vs linear regulator. Whats the different?

[codoyen]

Hi All, just trying to get my head around buck/step-down converter, resistor and linear regulators.

I understand they all change the voltage in a circuit, but I cant seem to work out when you would use one over the other.

It seems buck converter are the more efficient. linear regulators seem to be very inefficient, but can't seem to see where a resistor fits in.

So my question is when would you use one over they other?

 

[Audioguru]

A buck converter oscillates its output on and off and the filtering is poor so it cannot be used for audio or video.
A resistor does not produce a regulated voltage, instead it limits the current. since the current is limited then the voltage is reduced but is not regulated. If the load current is low then the output will have the same voltage as the input.
A linear regulator produces a fixed or adjustable smooth regulated output voltage.

 

[davenn]

So my question is when would you use one over they other?

A buck converter oscillates its output on and off and the filtering is poor so it cannot be used for audio or video.

not good reasoning, they are used in all sorts of audio and digital circuits
one just needs to ensure good filtering

I agree with the rest of AG's comments

 

[BobK]

not good reasoning, they are used in all sorts of audio

A class D amplifier being a prime example. It is a basically a buck converter for the audio output.

Bob