The main way of dimming LEDs is with Pulse Width Modulation (PWM). PWM dimmers are readily available but can be a bit pricey. Have a look here for a cheap one:
http://www.hero-ledstore.com/dial-dimmer-for-all-single-colour-led-tape-12v-dc-2-amps-max-p-856.html
They also sell dimmable MR16 which work with iron core transformers and standard dimmers but the bulbs are pricey.
I'm playing with their LED tape and one of their remote controlled dimmers.
http://www.hero-ledstore.com/dial-dimmer-for-all-single-colour-led-tape-12v-dc-2-amps-max-p-856.html
They also sell dimmable MR16 which work with iron core transformers and standard dimmers but the bulbs are pricey.
I'm playing with their LED tape and one of their remote controlled dimmers.
