Abstract: This invention is a circuit that actuates a loudspeaker at input frequencies above a predetermined threshold and mutes the loudspeaker at input frequencies below the threshold. The circuit includes a comparator that generates a pulse train proportional in frequency to an input audio signal. The pulse train is then coupled to a flip flop array. The flip flop array is controlled by a clock having a specified frequency and duty cycle. The clock, in conjunction with the particular number of flip flops, creates a time window in which pulses may pass. The output of the flip flop array is coupled to an enable input of an audio amplifier. When the frequency of the pulse train is great enough to allow a number of pulses equal to or greater than the number of flip flops to pass within the window, the loudspeaker is actuated. Below this frequency, the loudspeaker is muted.

Abstract: This invention is a circuit that actuates a loudspeaker at input frequencies above a predetermined threshold and mutes the loudspeaker at input frequencies below the threshold. The circuit includes a comparator that generates a pulse train proportional in frequency to an input audio signal. The pulse train is then coupled to a flip flop array. The flip flop array is controlled by a clock having a specified frequency and duty cycle. The clock, in conjunction with the particular number of flip flops, creates a time window in which pulses may pass. The output of the flip flop array is coupled to an enable input of an audio amplifier. When the frequency of the pulse train is great enough to allow a number of pulses equal to or greater than the number of flip flops to pass within the window, the loudspeaker is actuated. Below this frequency, the loudspeaker is muted.

Abstract: This invention includes a method for sensing the parasitic impedance in a battery charging system and compensating for these parasitic impedances. In one embodiment, the voltage of the system is measured with no charging current applied. Next, a charging current is applied and a second voltage is measured. The parasitic impedance is then extrapolated and multiplied by a predetermined rapid charging current. The product is added to a predetermined cell termination voltage. The charging means remains in a rapid charge current mode until a voltage equal to the sum of the impedance-current product and the predetermined voltage is reached, wherein the current is reduced to a maintenance charging level.

Abstract: This invention is a battery charging system that charges rechargeable battery cells by tracking a voltage profile charging curve across time. As all lithium based, like voltage cells have the same voltage profile across time, regardless of capacity, the invention presents a preferred embodiment of a universal charger capable of charging lithium batteries of varying capacities. Current is treated as a variable dependent upon voltage. Thus, in a preferred embodiment, cells of varying capacities will be charged at an optimal rate, thereby optimizing battery performance. One embodiment uses frequency selection to vary the rate of change in the output voltage of the system, thereby tracking the voltage profile charging curve across time.

Abstract: A method of charging a battery, and particularly a nickel battery, in a mobile charger, such as a vehicular charger, which is subjected to elevated temperatures. The method includes the steps of a first charging of the battery until a temperature inflection occurs, and then ceasing the charging while the battery temperature stabilizes. Then the battery is charged a second time, and a parameter is monitored for an indication of a full charge, such as temperature inflection or voltage cut-off. Preferably, when the battery reaches an elevated temperature, the charging is ceased until the battery stabilizes, and the charger monitors either temperature inflection, voltage cut-off, or a Coulomb count to determine when the battery has a full charge.