A lighting arrangement using LEDs that has an elongated translucent diffuser having a flat upper surface along the length of the diffuser. The transverse cross-section of the elongate translucent diffuser may have various shapes, all having substantially flat tops, including but not limited to quadrangular, rectangular, trapezoidal, and non-isosceles variations of these shapes. The elongated translucent diffuser is mounted on an elongated housing of substantially the same length to support the diffuser. The elongated housing may be solid or hollow and may contain the LEDs and circuit board, or the LEDs and circuit board may be contained within the elongated translucent diffuser. The LEDs are configured to transmit light through the diffuser so that the emitted light simulates light from a traditional neon tube.