I am wondering why you will need 5A to power just 3 fans and 6 leds. If they are PC power case fans, you don't need that much. Apart from the speed control, fans motors are generally friendly to dc ripples once you rectified your incoming 12VAC. I suggest you use a 2A ratings bridge rectifier with a filter for your power needs. A parallell rectifier configuration will also work for you. Please mark the post as helpful. If you need more help, provide more specification or post a document of what you are trying to accomplish.