Hello,I bought some really nice twig lights from Walmart today, they are on a transformer like most 'fairy light type things' but, the problem is that there is a really loud buzzing noise from the transformer, is this usual, don't remember other xmas lights over the years 'buzzing' when they are on a transformer.It's really annoying as you can hear it even when the tv is on. Any ideas? don't want to waste them.