While the simple circuit Rustu describes may work, it will definitely not comply with any regulatory standard that I am aware of! As I said in my previous post: Find out what the applicable standards are for your area and see to it that your circuit complies with them. If you are going to sell these devices, it may even be a criminal offence to do so if they do not meet the standards. In some countries it is mandatory to get a type approval for your circuit. Once again: Check with the appropriate authorities to see what you have to do!

Regards,
Rob.