Abstract: An apparatus and method for the moisture content measurement of compressible materials using pressure to firmly hold surface probes against the material to be measured. The apparatus uses moisture measurement circuitry employed in frequency domain impedance or time domain reflectometry devices to obtain moisture content readings from materials. These moisture content readings are based on the apparent dielectric constant of the measured material. Subsurface air voids or gaps found in loose, layered materials undesirably influence moisture measurement readings by reducing the apparent dielectric constant of the measured material. Pressure is supplied through the apparatus to the material in the proximity of the surface probes, thereby reducing air voids to enhance measurement accuracy. The apparatus and method are especially useful for compressible organic materials such as forest duff, hay and soil.

Abstract: An apparatus and method for the moisture content measurement of compressible materials using pressure to firmly hold surface probes against the material to be measured. The apparatus uses moisture measurement circuitry employed in frequency domain impedance or time domain reflectometry devices to obtain moisture content readings from materials. These moisture content readings are based on the apparent dielectric constant of the measured material. Subsurface air voids or gaps found in loose, layered materials undesirably influence moisture measurement readings by reducing the apparent dielectric constant of the measured material. Pressure is supplied through the apparatus to the material in the proximity of the surface probes, thereby reducing air voids to enhance measurement accuracy. The apparatus and method are especially useful for compressible organic materials such as forest duff, hay and soil.

Abstract: A low cost, highly efficient, lightweight device for regulating the luminous flux output of an incandescent headlamp as its battery supply voltage changes. The device maintains nearly constant output and allows nearly all of the energy capacity of the battery to be utilized. The device makes practical the use of low cost, readily available batteries to power wild land firefighter's headlamps. The output of an unregulated headlamp diminishes rapidly as the batteries discharge.