Abstract: A light-altering filter for use by military and law-enforcement personnel in lowlight environments is disclosed. The filter can be placed between a lit computer monitor screen and the face of the computer user. Light coming from the monitor screen is modified by the filter so that the night vision capabilities of the computer user are not adversely affected, and splash-back reflective illumination of the user is minimized.

Abstract: A soil moisture probe includes a capacitance-type probe and a detection circuit. The probe includes two spaced electrodes on the same side of a printed circuit board (PCB). The electrodes are placed on an inner layer of a multi-layer PCB and the detection circuit may be placed on an outer layer. The PCB also includes a ground plane. The detection circuit generates a sawtooth or triangular wave which is converted to a DC voltage representative of the moisture content of a soil sample into which the probe is inserted. The unique circuit uses the capacitance of the probe as part of a low-pass filter that distorts an oscillator-generated square wave into a saw-tooth or triangular wave. A resistance component of the low-pass filter is adjustable, allowing tuning of the probe and the circuit as needed.

Abstract: A device for measuring one or more different properties of soil or a soil-related substance is provided. The device includes a probe that is inserted into the soil or soil-related substance. The probe includes a tip. The tip is electrically insulative and defines apertures. Electrodes are fitted into the apertures. The tip and electrodes are machined together to have a desired shape that is suitable for insertion into a sample. A printed circuit board (“PCB”) is located inside the probe. The electrodes are soldered directly to the PCB in one embodiment. A temperature sensing element is also located in the tip, near the electrodes, and is connected electrically to the PCB.