Abstract: A battery charger outputs a high voltage even when a power supply device having a rechargeable battery is not connected to the battery charger so that the battery charger can supply the high voltage to the power supply device whenever the power supply device is connected to the output terminal of the battery charger. This battery charger has periodic signal producing means for supplying a periodically varying periodic signal to the output terminal by charging and discharging a capacitor connected to the output terminal, and detecting means for checking whether the power supply device is connected to the battery charger or not by checking through a filter whether the periodic signal is present at the output terminal or not. Thus, although the battery charger has no mechanical switch, it can detect the presence of the power supply device.

Abstract: An uninterruptible power supply unit for coupling between an adapter with an adapter connector and an electronic device in accordance with one embodiment of the present invention includes a self-contained housing, a backup power supply, and an output switch system. The self-contained housing has an input port for coupling with the adapter connector from the adapter and an output connector extending from the housing for coupling with the electronic device. The backup power supply is located in the housing and provides the backup power. The output switch system is also located in the housing. The output switch system is coupled between the output connector and the input port and the backup power supply and couples the backup power from the backup power supply to the electronic device when incoming power from the adapter fails.

Abstract: A transformerless battery feed circuit for a digital telecommunications line (100) presents a high impedance to digital signals and a low impedance to direct current, and provides a constant-voltage feed with current limiting. The battery feed circuit comprises a pair of transformerless controlled current sources, one for each lead (T,R) of the line, each taking the form of a high-gain transistor (Q1, Q2) having a collector coupled to a source of power (e.g., a battery V1), a base resistively coupled to the power source and capacitively coupled to its corresponding lead, and an emitter coupled to its corresponding lead. The battery feed circuit further comprises a pair of control circuits, one for each current source, each taking the form of a transistor (Q3, Q4) having a collector coupled to the base of the corresponding high-gain transistor, a base resistively coupled to the emitter of the corresponding high-gain transistor and to the power source, and an emitter coupled to the corresponding lead.

Abstract: For appropriately polarity recognition and corresponding switchover of a output stage of a proximity switch or the like connected to a supply voltage (VB), even while continuously activated, when a change in load polarity occurs, the proximity switch having in each case a high side driver and a low side driver, it is proposed to define on the output-side voltage axis between the positive supply voltage (+VB) and the negative pole or ground an upper and a lower detection window which sense the load configuration, each at a distance from the working points (which remain in a steady state) of each output stage driver, such that when a change in load configuration occurs, the potential of the output connection, to which the load configuration detection stage is connected, passes only briefly through these detection windows, and such that the transient signal changes which result therefrom in each window region are used for appropriately polarized switchover to the respective correct output stage circuit section b

Abstract: An apparatus for monitoring a battery pack having a plurality of serially connected rechargeable batteries. The apparatus comprises a means of detecting cell reversal and a means of protecting the batteries of the battery pack upon detection of cell reversal.