Abstract: The Schmitt circuit includes a first logic circuit that receives an output signal of the input logic circuit and has a first threshold voltage. The Schmitt circuit includes a second logic circuit that receives the output signal of the input logic circuit and has a second threshold voltage lower than the first threshold voltage. The Schmitt circuit includes a variable resistance circuit that adjusts the threshold voltage of the input logic circuit in accordance with an output signal of the first logic circuit and an output signal of the second logic circuit.

Abstract: A melt-spinning apparatus usable for producing various synthetic fibers in various manners, including a polymer melter; a heat-insulating housing having a detachable ceiling cover and a bottom having an opening; a detachable beam block having a cavity formed between a pair of longitudinal side walls, one of which has a polymer melt outlet; a melt-spinning pack arranged below the beam block and having a head projection inserted into the cavity, the head projection having a polymer melt inlet; a polymer melt passage system extending from the polymer melter to the polymer melt outlet; a fixing means for fixing the melt-spinning pack detachably to the beam block including a pushing member for pushing the head projection of the melt-spinning pack toward the longitudinal side wall having the polymer melt outlet to cause the polymer melt inlets to be fluidtightly connected to the polymer melt outlets, and optionally, means for protecting the polymer melt inlet from damage which the melt-spinning pack is inserted int

Abstract: A compact melt spinning apparatus having a screw-type extruder or extruders is provided. A metering pump or pumps, a molten polymer conduit or conduits and a spinning pack or packs and optionally the barrel(s) of the extruder(s) are positioned inside a heating frame encased in a casing of a thermal insulation material. The conduit(s) is arranged on a horizontal plane located above the spinning pack(s), and the extruder(s) and the metering pump(s) are arranged in a horizontal line and located above the conduit(s).