Abstract: A power and signal common transmission device comprises a power adapter, a wire case, a transmission cable and a switching regulator. The power adapter serves for transforming DC power into AC power. The wire case serves for transforming the power wire from the power adapter into output pins. The cable is connected from the wire case to the switching regulator. The switching regulator serves for dividing power and signal transmission path and decreasing a voltage of the input power. Therefore, the system is more stable and has a lower decay so that it can be used in a longer cable.

Abstract: An electric facility a cover secured on a primary circuit board and having one or more orifices, a secondary circuit board disposed on the primary circuit board and having one or more sockets engaged through the orifices of the cover, and one or more cables each having a plug for engaging into the socket and for coupling to the secondary circuit board. The secondary circuit board is received in a housing for being prevented from EMI. The plug and the socket each has a conductor coupled together and shielded by the plug and the socket for being prevented from EMI.