I wand to control some 220V lights with 12V but don't want the noise of s normal relay. So I saw these SSR but do not understand what Low level and High level mean. Is high level normally closed or normally open? And can these be controlled only with 12v? I ask this because they say 12V, but there is a + and a - where i understand you hook up the 12V, what than is has that CH1 input where they say you have to connect 5V to. So I need 12V to operate it and 5V to trigger it?