Electronic Engineering Glossary Terms

Dry-Air System. Provides dehumidified air for electronic equipment that is moisture critical. Related listing of Humidity Sensor Manufacturers [part of the equipment chassis design section].

Dry Cell. An electrical cell in which the electrolyte is not a liquid. In most dry cells the electrolyte is in the form of a paste. See Battery, also refer to Battery Manufacturers.

Dry Reed Relay. A Reed Relay that does not contain any mercury which is used in a Wet Reed relay to allow a lower contact resistance. Read more on Reed Relay Manufacturers

D-Sub. Short for D Sub-miniature. A style of connector with the mating end shaped like the letter 'D'. For reference see; D-Sub connector pin locations. Also refer to Companies producing D-Sub connectors. Also refer to the Keystone entire.

DTL. See Diode Transistor Logic.

D-Type Flip Flop. See D Flip Flop.

Dual Bus. A pair of parallel buses arranged such that the direction of data flow in one bus is opposite to the direction of data flow in the other bus.

Dual-Gate MOSFET. A two-gate MOSFET in which either gate can control the conductor independently, a fact which makes this MOSFET very versatile.

Dual In-Line Package. [DIP] An IC package having two parallel rows of performed leads which contains an integrated circuit. DIP packages are available in a number of lengths and widths depending on the amount of leads required and the complexity of the IC.[IC Package Type Definitions]

DIP IC

Dual Port RAM. A single RAM that can be accessed simultaneously from two different ports. A dual port RAM has one set of SRAM cells and two independent sets of addressing logic, called ports. The RAM cells may be read or written by either side independently and simultaneously. Some dual port ICs monitor access and won't allow the same cell from being accessed by both ports at the same time.

Dual Star. Two communication networks, each using a Star configuration which have been interconnected at their central point. One of three Star networks in common usage. Read more on Communication Networks, which includes more detail and graphics.

Duct. In interfacility cabling, a conduit, which may be direct-earth buried or encased in concrete, used to enclose communications or power cables.

Ductile. The propagation of radio waves within an atmospheric duct. Easily drawn out (as to form filaments or wires).

Ducting. Trapping of an RF wave between two layers of the earths atmosphere or between an atmospheric layer and the earth.

Dumb Terminal. An asynchronous terminal that does not use a transmission control protocol and sends or receives data sequentially one character at a time. A monitor/keyboard combination that used RS232 to access an embedded computer, as in a VT-100 terminal.

Dummy Bead. A small bead used to replace a through-hole lead which was not needed and not present on a component package. Dummy Bead adds stability to the component package and acts as a spacer or stand-off between the part and the board; see graphic to the right.

Dummy Load. A dissipative but non-radiating device that has the impedance characteristics of an antenna or transmission line. Also called Artificial Load. More information on Dummy Load. A dissipative impedance-matched network, usually used at the end of a transmission line to absorb all incident energy. A dummy load usually converts the incident energy to thermal energy.

Duplex Circuit. A circuit that permits transmission in both directions. Example RS485 Duplex Schematic. Note that the two types of duplex operation include Full-Duplex [transmission in both directions at the same time], and Half-Duplex [transmission in both directions one at a time].

Duplex Outlet. A pair of AC outlets in the same molded case.

Duplexer. A radar device that switches the antenna from the transmitter to the receiver and vice versa. Refer to the separate Dictionary of Radar Terms.

Dust Cover. A metal or plastic protective covering used to protect the mating end of a connector. More detail and graphics of Connector Dust Covers.

Dustproof. Constructed or protected so that dust will not interfere with its successful operation.

Dust-tight. Constructed so that dust will not enter the enclosing case under specified test conditions.

Duty Cycle. The ratio of high-time to low-time of a square wave. In a transmitter, ratio of time on to time off. In an ideal pulse train, i.e., one having rectangular pulses, the ratio of the pulse duration to the pulse period.

Dwell Time. The period during which a dynamic process remains halted in order that another process may occur.

Dynamic Microphone. A device in which sound waves move a coil of fine wire that is mounted on the back of a diaphragm and located in the magnetic field of a permanent magnet.

Dynamic RAM. [DRAM] A type of Volatile memory. A direct accessible memory (RAM) where the information is usually stored in the form of charges in a capacitor, DRAM must be continually powered and periodically refreshed, hence the name dynamic. Also see Volatile Memory IC Vendors.

Dynamic Range. The difference between the maximum over-load signal and the minimum acceptable signal in a system. In a system or device, the ratio of a specified maximum level of a parameter, such as power, current, voltage, or frequency to the minimum detectable value of that parameter.

Dynamic Memory. See Dynamic RAM.

Dynamic Power Consumption. The power consumed by a component while operating. Power consumed by a logic device while it switches state and drives a load.

Dynamic Speaker. A loudspeaker that uses a moving coil.

Dynamo. A generator that produces Direct Current [DC].