Recently I came across a small porcelain and metal Doorbell transformer made by Leviton Electric Mfg. Co. It is marked Magic 1152 6 Volts. This was probably one of the last porcelain ones made. Most are all metal nowadays an vey boring though some have nice graphics on their boxes. Since I last posted on Icon ones in my small collection I had added several more. Here is the small Leviton with the metal coil radiator around it and another transformer made by Signal Electric Mfg. Co. Wish the decal was a little better but they are both very neat styles. I have yet to find any patents by any companies for the doorbell transformer.