Abstract: A pH-meter capable of measuring conductivity and dissolved oxygen at the same time is composed of a gauge and three probes. Three power sources and three measuring circuits are mounted to the gauge. The detectors of the probes include a pH detector, a conductivity detector and a dissolved oxygen detector. Each of the probes is independently connected with the gauge via a transmission cable to be independently supplied with electricity and the signals of two probes are independently transmitted by electric insulation. Thus, the detecting elements can measure the pH value, conductivity, and dissolved oxygen at the same time with interference with one another.

Abstract: A dry and wet bulb psychrometer consists of a first temperature sensor, a second temperature sensor, a water tank, a water absorbing member, a computing circuit and a display screen. The water absorbing member is connected to the second temperature sensor and dipped in water in the water tank. The computing circuit is electrically coupled with the first and second temperature sensors for computing a humidity value by using the temperature values sensed by the first and second temperature sensors and displaying the computed result on the display screen for reading by a user. Thus, the dry and wet bulb psychrometer is convenient for application to provide high-precision level measurement.

Abstract: A waterproof pH meter includes a main unit, a probe, which includes a probe electrode and a signal processing circuit, and a waterproof signal transmission line electrically coupled between a main circuit in the main unit and the signal processing circuit of the probe. When measuring a solution, a potential signal generated by the probe electrode is amplified by the signal processing circuit and then transmitted to the main unit through the waterproof signal transmission line for reading by the user. As the design has a better capacity in bearing noise interference, the signal transmission line can be selected from a regular waterproof cable instead of a BNC material.