Abstract: A technique and device for rehabilitating or repairing waste water system components or the like, comprising a spray-applied, multi-layer liner which seals the components and imparts structural integrity. The liner comprises a primer layer, a first moisture barrier layer, a foam layer and a second moisture barrier layer. The first and second moisture barrier layers are preferably made of the same material and form a skin on both sides of the internal foam layer. The combination of the foam layer and the two moisture barrier layers imparts structural strength and rigidity to the cured liner. Preferably, the primer layer is an epoxy, the moisture barrier layers a polyurea and isocyanate blend, and the foam layer a polyurethane.

Abstract: A temperature stabilized amplifier is disclosed in the preferred and illustrated embodiment. This amplifier must perform in spite of extreme temperature fluctuations encountered in down hole tools. It must provide an output signal which is a large voltage swing input to a cable suspending the amplifier and other apparatus in a well bore. The apparatus utilizes complementary symmetry VMOS output transistors with a third VMOS transistor supported on a common heat sink with one of the two output transistors. The third transistor, in conjunction with an inverting amplifier, forms a bias which is applied to the output transistors in a manner such that temperature drift is cancelled. This, then, overcomes temperature drift. This extends the operating range of the equipment markedly.