Read the DD battery suggestion on several Harbor Freight blogs/sites. Not sure as to why, but would guess that the components may be different in the two designs. Your Aldi bug zapper is likely a better quality model. When one of our HF zappers takes early retirement I'll take it apart to try and get an idea as to how it was made. Something along the lines of a transistor, transformer, capacitor, and resistor. Off the shelf items that the builder recognized would work; components unlikely to have been made for the purpose of building a zapper. But what the hey, they're fun. And effective.
