I want to design a charging unit for IPhones. I have made a prototype but it’s not how I want it to be. I want the two separate retractable mechanisms to be connected to one usb output which will stay stationary. The problem I have at the moment is both wires have to be pulled at the same time for it to work effectively. I believe it would be similar to a retractable extension lead but I have no idea what I’m doing!