Ampere (Amp) -Unit of electrical current

Amp-hour (Ah) - Unit of electrical energy, one amp of current flowing for one hour

Amplifier - A circuit that increases the voltage, current, or power of a signal.

Analog - Information represented as continuously varying voltage or current rather than in discrete levels as opposed to digital data varying between two discrete levels.

AWG - Abbreviation for "American wire gauge". A gauge that assigns a number value to the diameter of a wire.

Battery - A DC voltage source containing two or more cells that convert chemical energy to electrical energy. The most commonly used battery in the security industry is a Sealed-Lead-Acid back-up or stand-by battery.

Circuit - Interconnection of components to provide an electrical path between two or more components.

Circuit Breaker - A protective device used to open a circuit when current exceeds a maximum value - in effect, a reusable fuse.

Closed Circuit - Circuit having a complete path for current flow.

Contact - Current carrying part of a switch, relay or connector.

Current – Current is the quantity of electrons passing a given point. Current is like the water flowing through a pipe, while voltage is likened to the water pressure.

Current draw – Amount of current a device needs to operate

Dead Short - Short circuit having zero resistance.

DC (Direct current) - An electric current flowing in one direction only.

Decibel - (dB) a logarithmic representation of gain or loss. Siren volume is rated in dB.

Digital - Relating to devices or circuits that have outputs of only two discrete levels. Examples: 0 or 1, high or low, on or off, true or false etc.

Fuse - A protective device in the current path that melts or breaks when current exceeds a predetermined maximum value.

Ground - An intentional or accidental conducting path between an electrical system or circuit and the earth or some conducting body acting in place of the earth. A ground is often used as the common wiring point or reference in a circuit.

Impedance - (Z) Measured in ohms it is the total opposition to the flow of current offered by a circuit. Impedance consists of the vector sum of resistance and reactance.

Jack - Socket or connector into which a plug may be inserted.

LED - Abbreviation for "light emitting diode."

Linear – The relationship between input and output in which the output varies in direct proportion to the input.

Line Fault Monitor – Detects dead phone line by monitoring telephone line voltage, current, or both conditions. (Elk monitors both.) When a dead phone line is detected, it signals local, external equipment (such as the alarm panel) via a relay based on the selected alarm time delay.

Mhos - Unit of conductivity - the opposite of Ohms.

Mil - One thousandth (0.001) 1 Amp (A) = 1,000 milliamp (mA)

Negative – A terminal that has an excess of electrons.

Negative Charge - A charge that has more electrons than protons

Normally Closed – A designation, which states that the contacts of a switch or relay are closed or connected when at rest. When activated, the contacts open or separated.

Normally Open – A designation, which states that the contacts of a switch or relay are normally open or not connected. When activated the contacts close or become connected.

Ohm - Unit of resistance symbolized by the Greek capital letter omega (Ω) – the opposite of Mhos.

Parallel – A circuit having two or more paths for current flow, also called shunt.

Polarity - Term used to describe positive and negative charges.

Positive - Polarity of point that attracts electrons as opposed to negative, which supplies electrons.

Positive Charge - A charge that has fewer electrons than protons.

Power – The work performed by an electrical current, with the unit of power being the watt.

Power Supply - Electrical equipment used to deliver either AC or DC voltage - can be Linear or Switching.
Linear: A linear regulated supply maintains a constant output voltage by throwing away the difference between input and output voltage times current as heat. Linear power supplies are classified as such because they eliminate excess energy (power) by dissipating heat to the surrounding air. This form of conversion is simple and thus was the first to be used for power supplies. Simplicity also constitutes the major advantage of linear power supplies. The major disadvantage to them is their lack of efficiency, usually only 30-50%.
Switching: A switching power supply, or switcher, maintains a constant output voltage by storing the difference between input and output voltage times current in a magnetic field, then periodically drawing out this stored energy. The latter device is much more efficient. There are both advantages and disadvantages of a switching mode power supply versus a linear supply. The major advantage is the increased efficiency, upwards of 80% in some cases as well as minimized space. However in order to achieve this efficiency, increased complexity and RF interference are introduced.

The difference between linear and switching mode power supplies is the regulators. The switching mode regulator converts the DC input to an AC output through the use of a switch. This AC waveform can then be filtered back to a DC value. Instead of dissipating the proper amount of heat as in a linear regulator, the output of a switching mode regulator is controlled by the duty cycle of the switch, i.e. the percentage of time the switch is on.

Printed circuit board (PC board) - Insulating board containing conductive tracks for circuit connections.

PTC – Positive thermal coefficient circuit breaker

Pulse - Rise and fall of some quantity (usually voltage) for a period of time.

Relay – An electromechanical device that opens or closes contacts when a current is passed through a coil.

Single pole double throw (SPDT) Single pole designates a single switched output, while double throw means 2 conditions – on or off. A single throw would be on or nothing.

Double pole double throw (DPDT) - Double pole designates a dual switched output, while double throw means 2 conditions – on or off.

Self contained Siren – A speaker complete with an electronic siren driver circuit board.

Siren driver – An electronic circuit board that generates sounds to be played through a speaker.

Unique Features on ELK Sirens and Siren Drivers:

MilliMiserTM -This exclusive option allows further reduction of current draw (25% current draw reduction with only 6-8% reduction in volume). Excellent for use with controls that have limited alarm or auxiliary output power.

ComboTriggerTM - This unique feature produces two distinct sounds, even from controls that only have a single alarm output with a pulsing option for fire or burglary.

VolumeStepTM - This exclusive feature is best described as a “peacekeeper”. When selected, sounds play at a low volume, gradually rising to full volume within 90 seconds.

Slow Sweep (Siren sound) – Slow Sweep is a feature from ELK PRODUCTS that allows a single alarm output panel to produce two unique sound patterns to differentiate between a fire or burglary situation. If steady current is applied, the slow sweep sound starts off low and ramps up loud and then turns off and the process repeats. If a pulsed current is applied, the slow sweep is broken during start up to produce a totally different sound.

Surge suppressor - a device inserted in the alternating current (AC) utility line and/or telephone line to prevent damage to electronic equipment from voltage "spikes" called transients. The power (or phone) line is effectively short-circuited to electrical ground for transient pulses exceeding the threshold. A more accurate term for this type of device is "transient suppressor." Transients, which arise from various causes (not just lightning), commonly reach peak levels of several hundred volts. The worst type of transient occurs when lightning strikes in the vicinity. Such a "spike" can peak at thousands of volts and cause permanent damage to equipment. Surge suppressors should be used as a matter of habit with all semiconductor-based electronic and computer hardware (like security controls). * copied from www.whatis.com

Speaker - Also called "loudspeaker." Transducer that converts electrical energy into mechanical energy at audio frequencies.

Structured Wiring – A planned wiring method by which all services (phone, data, television, music, and security) originate from a central location or hub.

Transformer - Inductor with two or more windings. Through mutual inductance, current in one winding called a primary will induce current into the other windings called secondaries.

Volt - Unit of potential difference or electromotive force. One volt is the potential difference needed to produce one ampere of current through a resistance of one ohm.

Voltage (V) - Term used to designate electrical pressure or force that causes current to flow.

Volt-Ampere (VA) - Unit of apparent power in an AC circuit containing capacitive or inductive reactance. Apparent power is the product of source voltage and current.

Watt - Unit of electrical power required to do work at the rate of one joule per second. One watt of power is expended when one ampere of direct current flows through a resistance of one ohm. In an AC circuit, true power is the product of effective volts and effective amperes, multiplied by the power factor.

Wattage Rating - Maximum power a device can safely handle continuously.

Wire – Single, solid, or stranded group of conductors having a low resistance to current flow. Used to make connections between circuits or points in a circuit.

Wire Gauge - American wire gauge (AWG) is a system of numerical designations of wire diameters.

Wireless - Term describing radio communication that requires no wire between two communicating points.

X10 – A method of sending a signal over the existing 120VAC wiring in a home to control lights or appliances, known as line carrier. This method of home automation is great for retro fit and usually does not require additional, expensive re-wiring of the home. X10 modules simply plug into the existing outlet and the lamp or appliance is plugged into the X10 module. Each X10 module can have its own unique address to control individual devices so that multiple devices can be used.

Yelp (Siren Sound) - Yelp is a common term in the security industry used to describe a specific type of noise generated by a siren driver or a control panel. The sound could be described as a fast woo-woo sound. This sound is commonly associated with a burglary situation.

*** Most definitions found at http://www.twysted-pair.com; however, some we “created” on our own, and the one on surge suppressors was copied from http://www.whatis.com .