I'm making a DC colloidal silver generator (planning to use four rechargeable 9v batteries). The positive and negative wires that clip to the silver rods must be switched every few minutes throughout the process so the two rods wear evenly. The process takes several hours. Is there a simple way to reverse them at a set interval with a switch or dial at the project box rather than having to disconnect the wires and reconnect every few minutes. It would be great if I could set the interval and leave it, but if I can't do that, I'd be okay even if I had to flip a switch back and forth. Thank you in advance!