Accurate manual adjustment of a desired delivered flow rate in an intravenous liquid injection system is expedited and simplified. A programmable counter, fed by a pulse train of known repetition rate, is pre-set in accordance with the volume of liquid to be delivered, the size of the individual liquid drops, and the desired length of time during which the liquid is to be delivered. The counter provides a pulsed visible and/or audible indication at the drip rate determined by the pre-set conditions. The operator, upon comparison of the actual drip rate with the pulsed indication rate, can readily adjust the drip rate to coincide with the indications. The apparatus may include a pulse per unit time readout capability.

A time calculation ring counter is made of a plurality of negative resistance light emitting elements, which provide display of current time information. In a preferred form, a plurality of GCR's (gallium arsenide gate controlled rectifiers) or a plurality of GND's (gallium arsenide negative resistance light emitting diodes) are aligned in a circular fashion on a display panel of an electronic timepiece. The GCR's or GND's function to either calculate the time information or indicate the time information.

A single character matrix display system in which plural associated characters which constitute a word representing time, temperature, or other information are displayed sequentially, one at a time. The words are generated in electronic form by known means. Individual characters are sequentially selected and then supplied to a single character matrix display station in the order in which they would normally be read by an observer. The plural character word can be repetitively displayed, with the display being de-energized (blanked) for an interval before the word is repeated. Alternatively, if the information to be displayed represents time or some other changing data or words, a new word will be displayed, character by character, after the end-of-word blanking interval. The single character display station comprises a matrix of character component parts (strokes or dots) which are selectively illuminated or actuated in predetermined patterns to represent the characters to be displayed.

An analogue display includes an electrical sensitive medium enclosed between two sets of electrodes. The two sets of electrodes are registered and overlap to provide background and one or more shaped index characters, each at a plurality of selectable positions. Voltage signals are applied to the electrodes so that the medium is held in an OFF state in the region between selected electrodes, while simultaneously voltage signals are applied so that in other regions of the medium, the medium is in an ON state. The medium may be of liquid crystal, electroluminescent or gaseous material. One set of electrodes may have a meander configuration, the other set a segmented configuration. The index character or characters may be displayed at one, two or three positions, each character being of different shape, for meter or timepiece applications. The voltage signals applied may be binary coded and in preference pseudo-random sequence binary codes.

An emergency lighting system for an aircraft comprises networked light units that communicate wirelessly with a master controller to switch the light units on in an emergency. Each unit has its own battery power source and is arranged conserve power consumption by cycling between an operable (awake) condition in which it can communicate with the master controller and an inoperable (sleep) condition wherein the wake-up time is approximately 1 millisecond or less. Power consumption is also reduced by employing LEDs as the light source and pulsing the LEDs with a variable load factor to adjust the illumination level.