Hmmmm...well I am just going to show my ignorance/lazyness here. But when you say 230VAC Mains Voltage it kinda scares me cuz all I really need is like 18v p-p. The project I am trying to finish is a portable frequency source using 18vdc (i.e. 2-9v batteries)with a variable frequency output (i.e. 1hz, 10hz, 100hz....). Now here is where I am trying to be lazy...I know I need the batteries and I know I need the variable output so I am looking for a god amoungst men, A knight in shining armor to come and tell me everything I need after the batteries. A schematic and parts list would be the bees knees but I will take any help I can get.