An amplifying circuit comprises a bias circuit, a reference circuit, a first circuit, and an amplifying sub-circuit. The invention also concerns an enclosure into andor from which the optical fibers pass through an aperture, which is sealed by an adherent patch, or flap with the fibers sealed between the exterior surface of the enclosure and an overlying portion of the patch or flap. The blades are arranged along a single blade axis that is disposed oblique to, preferably perpendicularly to, the longitudinal axis of the handle.