As a retired commercial troller I always used voltage fields (black box) to attract fish. Since retiring, I have developed a line of "voltage tuned" lures and attractors. I can essentially make 80% of receptive fish take a "tuned" lure over a plain identical one when trolled side by side. This applies to springs, coho, some trout and most recently, kokanee. I use long lasting natural elements, NO BATTERIES!
Products include Portable Black Box (designed for braid, but work on stainless), spoons, hoochies, plugs (new for 2017) and tuning components. Everything comes in both fresh and salt water. Check the testimonials at www.lurecharge.com