transformer for leds bulb

[corben dallas]

hello and thank you for your answers in my previous post.
I have three questions about transfos.

1 - what does (20-60VA) mean on my transformer?
2- What is the difference between 12V AC and 12V DC?
3- for 3 bulbs of 1,5 watts with 18 LEDs each, what type of transformer should I put because my halogen transformer (220v / 12vAC (20-60VA cos = 0.99) cannot make them work?

Thank you for your answers .

[Denys]

to answer your first question the VA means Volt amp roughly a transformer of 12v output and 10va can only deliver you 0.8A so + -10w (must take into account the cos, here it is for a cos = 1 , so you must multiply it by cos0,99).
a tfo in ac is a transformer which delivers alternating current one in DC is continuous.
For your 3 bulbs, you must know what voltage it was originally intended for (number of batteries and type of batteries).
Because I don't know how the diodes are connected in your bulbs.