Terrible product these are junk. They work for a while then. Well in my case, after about 6 months of use it completely stops working. One day you will go to use it and it just won't power on with battery or by 9V DC input. Electronics repair shop say they can't repair IC's damaged as no power protection on circuits. Waste of money. Another example of cheap badly made Chinese junk electronics. Best advice is do not buy these they won't last!