12v DC cockpit light dimmer ?

I'm rigging some cockpit lighting using a 12v DC converter from an old cassette deck and some 12v bulbs from radio shack.
My question is, what can I use as a dimmer ? - I remember having a cheap old dimmer from a cheap electronic kit when I was a kid, but no one seems to know if its not 120v AC.
My question is, what can I use as a dimmer ? - I remember having a cheap old dimmer from a cheap electronic kit when I was a kid, but no one seems to know if its not 120v AC.