Vehicle speed signal pulse source

A vehicle speed signal pulse source comprising, input and output terminals, a substantially E-shaped magnetic structure wherein two legs of the E form a pair of magnetic circuit branches, a common primary winding wound about both of said pair of magnetic circuit branches and connected to said input terminals, a second winding wound about one of said pair of magnetic circuit branches and connected to said output terminals, a signal connected to said input terminals to produce magnetic fluxes in both of said pair of magnetic circuit branches, the last leg of the E including a permanent magnet forming another magnetic circuit branching of said substantially E shaped magnetic structure and causing magnetic flux to pass through both of said pair of magnetic circuit branches, and a rotatable magnetizable member positioned adjacent the legs of the E for increasing the reluctance in one of said pair of magnetic circuit branches at a time at a rate dependent upon the speed of rotation of said magnetizable member.