I have a toy "activity center", which uses 4 c batteries. As the baby grows, the batteries exhaust quicker and quicker. I want to buy a 6v ac-dc adaptor, and connect the wires to the toy, instead of using 4 c batteries. I know many people will say it is not safe, but of course I will keep the wires and the DIY work safe for my baby. My question is: how many mA output should I buy, to drive the toy making flashing lights and sounds as 4 c batteries? 300mA? 500mA? 1000mA? Thanks!