I live in Wisconsin with forced air heating which can get pretty dry in winter. I’ve been using a Venta brand room humidifier. It consists of a slowly rotating plastic drum with multiple fins which is partially immersed in water as a fan blows the air above it. It puts about a gallon of water per day into the room air where I practice. It’s able to keep the RH at about 40%, but that’s about it. There’s no way it could reach 50% unless I bought another one. The nice thing about it is that there are no pads to change and no dust problems.