Abstract: A kit is provided for testing a gas produced from a sample for an absolute amount of a hydrogen sulfide. The kit includes a vessel for receiving the sample to be tested. The vessel includes one or more gas flow passages through which gas within the vessel can leave the vessel. The kit also includes one or more testing tubes. Each testing tube includes a lumen through which gas can flow. The lumen includes a column of medium observable from outside the testing tube and has a length which changes in appearance in proportion to the amount of hydrogen sulfide which has passed through the testing tube. Graduations are included on the one or more testing tubes for indicating the length of the column of medium whose appearance has changed. The kit also includes a coupling mechanism for coupling the one or more testing tubes with the one or more gas flow passages such that gas leaving the vessel passes through the one or more testing tubes.

Abstract: A reference voltage generator includes a current mirror circuit connected to a power supply voltage and having a plurality of transistors which are coupled in parallel to the power supply voltage, a reference current circuit connected between the current mirror circuit and a ground for generating a reference current in accordance with an differential operation, a feedback circuit for applying the reference current to the current mirror circuit, and a constant voltage circuit having an operational amplifier whose input terminal is connected to the current mirror circuit for generating the reference voltage.

Abstract: A sensorless and brushless DC motor in which phase-corresponding coils are turned on at an electric angle of 180.degree..The driving circuit of the DC motor includes comparators for outputting position detection signals, comparators for outputting turn-on signals, power transistors for turning on phase-corresponding coils, a rotation direction control section, a charge/discharge control section, a charge/discharge section, a turn-off signal generating section, and transistors for forcedly turning off the power transistors.

Abstract: A transport device for handling wafers of different diameters utilized in the manufacture of semiconductors. A robotic arm is equipped with a fork-shaped wafer support board and an arm slide movable relative to the robotic arm. The fork-shaped end of the support board is provided with fixed pins on one side to support wafers and on another side with plate springs carrying pins which can be depressed by the weight of a wafer to accommodate larger size wafers. The device permits wafers of different diameters accurately and safely to be transferred from its center to a predetermined station without the need for changing the wafer support board or correction of the robotic arm.