I need to light 3 x ½ W leds from a power supply which gives 28V. If I use the 3 leds in series, I have to use a 220Ω 2W dropping resistor in series on the line which uses more power than what the 3 LED's would use which is not worth using the LED's, so what would be the best possible and cheap way to light these led's without much loss?