I've purchased a Sennheiser L2015 charging station and battery paks for our wireless mics and (*SURPRISE*) it doesn't include the power supply. The one they offer(the NT-1) list for it about $90 dollars and out of stock at Sweetwater and is list as discontinued at B&H PhotoVideo. Its power requirement are listed as Input 12v DC /750mA max. Inside positive, outside negative. I was hoping someone might be aware of a more cost effective solution.