adjustable power

hello everybody,
I need to power a high-powered ledRGB + arduino,

the power has to be adjustable in order to make tests with different LEDs;
these LEDs need between 1200mA and 1500mA and 9V and 20V.

what is the right way and easy,
what is the right way and DIY to learn along the way
and not die (electrocuted)?

The most satisfactory long term solution is to get a bench power supply (these have adjustable output voltage and current, but cost money).

Some voltage regulator chips are designed to be adjustable using a potentiometer, such as LM317 / LM117 - this provides a cheaper way to create your own adjustable supply, assuming you have a 15V+ 1.5A+ supply to feed it...

thanks for the response,
can you recommend some economic model?

I have no supply,
know of a tutorial on power?