Barometer with trend indicator switch and logic circuit - has single integrated circuit contg. three identical gates

摘要

A barometer with a trend display has three indicator elements connected to a logic circuit driven by a contact device consisting of two fixed contact elements and a third contact moved between them by a barometer cell so as to provide the logic circuit with a control signal corresp. to rising, falling and variable air pressures. The logic circuit (8,10,12) is very simple and contains very few components. It consists of a single integrated circuit of the TTL or CMOS type. The logic circuit contains three identical gates (8,10,12), pref. NOR gates, two (8,16) of which have inputs connected to the fixed contacts (6,7) and drive two indicator elements (9,11) as well as the third gate (12). The third gate (12) drives the third indicator element (12). The circuit exhibits low current consumption and low mfg. costs.