Abstract: A drive circuit for a solar lamp includes a thermistor TH1 that reduces a power supply to a lamp if a Mosfet Q1 to which it is physically mounted becomes too hot. Also, a resistor R37 sets at low voltage level below which the battery will be isolated. This serves to set a lower but safe level than the voltage at which the circuit in block A isolates the battery during optimum operating conditions of the lamp. Such components prevent or at least inhibit the possibility of the battery being discharged beyond a level from which it cannot recover.

Abstract: Apparatus for providing an electrical system with protection against electrical shock in the event of a ground fault. The electrical system supplies power from a central mains inlet to at least one local electrical device. The central mains inlet includes a central ground fault detector and interrupter actuatable upon detection of a first predetermined level of current imbalance to interrupt the central mains inlet. A local ground fault detector is associated with the at least one local electrical device and is actuatable upon detecting a current imbalance of a second predetermined level which is lower than the first predetermined level. Controls are effective upon actuation of the local ground fault interrupter to actuate the central ground fault detector to cause it to interrupt the central mains inlet.

Abstract: A solar panel unit includes a solar panel (10) supported for rotation about a frame (13) and driven around the frame (13) by an electric motor (14). Radiation sensors (22) and (23) have their planar axes equally and oppositely off-set from the planar axis of the panel (10). Signals from the sensors (22) and (23) are monitored and used to control the operation of the motor (14) such that the panel (10) moves as the sun moves during daylight hours and the panel remains with its planar axis at right angles to rays of the sun throughout the day.

Abstract: A combined tape measure and calculator is arranged with equally spaced holes along the length of its tape. The holes are read by a number of closely spaced optical readers arranged to generate incremental unit signals for a microprocessor mounted in a case of the tape measure.

Abstract: A toothbrush (10) for applying an electrical stimulus to the gingival region has an electrode (40) on the handle and an electrode (22) having nibs (24) at the base of the bristles (20). Electronic circuitry (28) is housed in the handle (14) for applying a bipolar voltage waveform, which is preferably a square wave of about 50 Hz, across the electrodes (22,40). A device such as an LED or buzzer is provided for indicating when the toothbrush is switched on.

Abstract: An electro-therapeutic device comprises an elongate hand held casing 1 having a tip electrode 4 at one end and an electrode 11 along one side. The tip electrode 4 is placed against the body and a high voltage (40 to 90V) is passed between the electrodes to stimulate the body at low resistance or acupuncture points. In a first aspect of the invention a low voltage DC current passes through the body and changes in the resistance of the body are used to modulate an audible signal to indicate when a low resistance point is reached. In a second aspect the casing 1 is of elongate cross-section so that electrode 11 sits snugly in the web of the hand. In a third aspect of the invention a pulsed, bipolar waveform is applied to the electrodes to avoid electrolytic action in the body. A solid state (transistor/diode) switch is also described for connecting the electrodes across a secondary winding of a transformer during a stimulation mode.

Abstract: A liquid monitoring device includes means for detecting the presence of a liquid and means for giving an alarm when the liquid is detected. Preferably a temperature sensor is also provided and the temperature is displayed on an LCD. The temperature sensor is arranged to sense the ambient air temperature at a first sampling rate and then the liquid temperature, after the liquid has been detected by a detector, at a second, more frequent sampling rate. The components are housed in a casing which carries a pivotably mounted sucker for attachment to a wall or bath.

Abstract: A distance measuring device including a casing bearing a visual display and incorporating therein a transmitter for directing signals toward a selected surface; a receiver for detecting echoes from the selected surface; distance calculating circuitry for measuring the distance to a selected surface in accordance with the transit time of the signal; visually displaying the calculated distance; memory for storing at least two displayed distances measured in perpendicular directions; multiplication circuitry for multiplying the stored measurements; and visually displaying the product of the multiplication. The device further includes a key to effect the operation of the device whereby a distance is displayed, another key to initiate the storage of a displayed distance; and a key to initiate the multiplication of the stored distance measurements.