O

OCR (abbreviation) See optical character recognition.

O-crimp (terminal) An insulation support crimp for open barrel terminals (and contacts). Its crimped form resembles an "O" and conforms to the shape of the round wire insulation. O-crimp is also used to describe the circumferential crimps used on round, tubular ferrules.

offset current (circuit) An operational amplifier characteristic. The difference in current at the two inputs to bring the output voltage to zero.

ohm (measurement) The unit of measurement for electrical resistance. A circuit is said to have a resistance of one ohm when an applied emf of one volt causes a current of one ampere to flow.

ohms per square (measurement) A unit for measurement of resistor value by topological shape. It is based on the fact that the resistance of a square of resistor material is independent of the dimensions of the square. A resistor topology can be considered to be made up of contiguous squares. The value of the resistor is the product of the number of squares and the ohms per square.

olefin (material) Types of unsaturated aliphatic hydrocarbons, including ethylene, propylene, and butene. They are the bases for such plastics as polypropylene and polyethylene.

open barrel (terminal) See barrel.

open loop (circuit) Refers to operation of an amplifier without feedback, as opposed to closed loop which is operation with feedback.

operating time (relay) (device/circuit) The time interval between satisfaction of the specified input conditions and the occurrence of the specified operation.

operational amplifier (op amp) (circuit) Originally, an amplifier to perform mathematical operations. An amplifier with two differentially connected inputs, with high voltage gain, and with one output - which ideally is at zero volts when both inputs are at zero volts. It must also be capable of accepting negative feedback without oscillating.

optical fiber (fiber optic) Also called fiber-optic cable. A thin, flexible glass or plastic fiber capable of transmitting light over considerable distances by internal reflection.

oscillator (circuit) Any non -otating device for setting up and maintaining oscillations of a frequency determined by the physical constants of the system.   A device for producing electric oscillations; specifically a radio-frequency or audio-frequency generator (especially of the non-rotating type).

OSHA - Abbreviation for Occupational Safety and Health Act, specifically the Williams-Steiger Law passed in 1970 covering all factors relating to safety in places of employment.
output (computer) Information transferred from the internal storage of a computer to output devices or external storage.

ovaled (terminal) A terminal (or contact) whose barrel has been made oval in shape to aid in placing two wires in the barrel.

oxide (general) A compound of oxygen with one or more metallic elements. Rust is an oxide of iron.

oxygen index (measurement) The minimum concentration of oxygen, expressed as volume percent, in a mixture of oxygen and nitrogen that will just support flaming combustion of plastic initially at room temperature.

ozone (general) An extremely reactive form of oxygen, normally occurring around electrical discharges. It is faintly blue and has the odor of weak chlorine. In sufficient concentrations, it can break down certain rubber insulations under tension (such as a bent cable).