Abstract: A system for determining whether a bar of precious metal has a purity of composition which is within a given range of variance. Heat is induced in one end of the bar using an induction heater powered by a high frequency power source, and the time vs. temperature response at the other end of the bar is monitored.

Abstract: The composition of a sample is determined with reference to a recorded standard using the same heater and sensor as that used to record the standard, by testing the sample only when its temperature has reached an equilibrium, and by compensating for differences in environment and starting temperature; accurate heater control is insured by maintaining a constant voltage across a series circuit consisting of a heater and a resistance load equal to the resistance of the heater; the heater is pulsed in an initial test sequence to heat the system to above ambient so that heat losses to the environment are substantially the same from test to test; a dynamic insulation system prevents heat loss from the sample under test; an improved test based on the sensed temperature of the sample immediately after the heater is turned off detects the presence of tungsten forgeries; a compensated infrared sensor eliminates the need for a direct contact temperature sensor; and tests are provided for determining various physical ch

Abstract: An electric guitar is described which provides signals from each of its electrically conducting strings by the cutting of magnetic field lines. The magnetic fields are produced by removably mounted permanent magnets which produce concentrated fields. The return wire or wires of the strings are near the surface of the neck. Various circuit configurations are used to minimize noise pickup, to combine the signals from each signal and to modify the sound produced by each string.

Abstract: A way to determine, nondestructively, the purity or composition of an unknown material sample such as, for example, a sample of gold or silver of unknown purity. The procedure involves subjecting one end of an elongate sample of known length and weight to a temperature elevated relative to that of the sample and comparing the time-varying temperature pattern at the other end thereof during finite lengths of time with that of a known or identically-sized standard subjected to equivalent or the same conditions for an interval of time of the same finite length. The temperature of said other end can be monitored during the time heat is applied and/or after it is withdrawn.