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HP-19C calculator HP-29C with AC-powered battery charger. The HP-19C and HP-29C were scientific/engineering pocket calculators made by Hewlett-Packard between 1977 and 1979. They were the most advanced and last models of the "20" family (compare HP-25) and included Continuous Memory (battery-backed CMOS memory) as a standard feature.
A battery charger, recharger, or simply charger, [1] [2] is a device that stores energy in an electric battery by running current through it. The charging protocol—how much voltage , amperes, current, for how long and what to do when charging is complete—depends on the size and type of the battery being charged.
HP-19B, introduced on 4 January 1988, along with the HP-17B, HP-27S and the HP-28S, and replaced by the HP-19BII (F1639A) in January 1990, [2] was a simplified Hewlett Packard business model calculator, like the 17B.
Button, coin, or watch cells. A button cell, watch battery, or coin battery is a small battery made of a single electrochemical cell and shaped as a squat cylinder typically 5 to 25 mm (0.197 to 0.984 in) in diameter and 1 to 6 mm (0.039 to 0.236 in) high – resembling a button.
As the removable plug was returned to the socket, the wires were reeled back into it. The circuit was closed either by pressing a button or removing the igniter from its socket. [4] The modern "automatic" removable automotive V-Coil lighter was developed by Casco in 1956, [6] for which it received U.S. patent 2,959,664, issued in 1960.
A power converter is an electrical device for converting electrical energy between alternating current (AC) and direct current (DC). It can also change the voltage or frequency of the current. Power Converters can include simpler tools such as transformer or more complex like a resonant converter .
On a single-step or immediate-execution calculator, the user presses a key for each operation, calculating all the intermediate results, before the final value is shown. [1] [2] [3] On an expression or formula calculator, one types in an expression and then presses a key, such as "=" or "Enter", to evaluate the expression.
A charge controller, charge regulator or battery regulator limits the rate at which electric current is added to or drawn from electric batteries to protect against electrical overload, overcharging, and may protect against overvoltage. [1] [2] This prevents conditions that reduce battery performance or lifespan and may pose a safety risk. It ...