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A twinkle bulb is a special type of light bulb which blinks on and off for decorative effect. They are most commonly used on Christmas lights and other string lights, but can also be used for other ornamental purposes like electric jack-o-lanterns for Halloween and replica traffic lights.
The original twinkle bulbs were C7½ and some C9¼ incandescent light bulbs with a bimetallic strip. Once the bulb warms up, the strip pulls slightly away from the contact, opening and interrupting the parallel circuit through the bulb and turning it off. The bulb then cools, allowing the strip to bend back and make contact again. This repeats at semi-random intervals ranging from several to less than half a second, and they may appear to speed up and slow down in a "cycle". Different bulbs may behave differently, even if purchased in the same package, due to minor manufacturing differences between each one. Since the trigger is thermal, blinking will be reduced or stop altogether if the lights are turned down with a dimmer.
When used across a large area such as a Christmas tree, the lights create a sparkling effect. Visitors to some department stores have likely seen these on displays, Macy's still uses them in its stores. Although now difficult to find for sale at local retailers, they are still available though online shopping.
The advent of miniature lights found the adaptation of twinkle bulbs as flasher bulbs, which interrupt the entire series circuit of anywhere from 10 to 50 bulbs when powered from 120-volt mains electricity (in North America). These are easily recognizable by their red tips on an otherwise unpainted clear white bulb, and are available in the different voltages required for 10, 20, 35/70, and 50/100/150/200-light sets. Some older mini-light sets interlaced two circuits, putting all of the odd-numbered bulbs on one and the even-numbered ones on the other, allowing some lights to remain on while others between them blinked off. Some sets of 100 did this, others had the more common sequential (non-interlaced) setup but were advertised as "5-way flashing", having five circuits of 20 bulbs. These sometimes had a socket of a different color to indicate where each circuit began. [1]
When placed in a battery-operated set, these bulbs will flash individually since these sets are wired in parallel. This also prolongs battery life since the bulbs are off part of the time. AC sets with shunts in their sockets such as NOMA "Stay Lit" will also blink individually as the shunt routes power around them.
During the late 20th century, flasher bulbs were modified such that the bimetallic strip is a "normally open" switch instead of a "normally closed" one. When first turned on, the strip does not make contact, causing power to flow through the filament until it warms up within a few seconds. It then makes and breaks contact quickly, momentarily allowing a low-resistance path around the filament, causing the bulb (and to a lesser extent the steady bulbs in reaction) to flicker rapidly, much faster than most flasher or twinkle bulbs.
These 6-volt bulbs were originally half of the bulbs in a 35-light set, alternated in every other socket with 6-volt steady bulbs (instead of the 3½-volt ones in a normal set of 35), and were sold under the General Electric brand and at Macy's under its own house brand, among others.
Ones sold in the 2010s were much more cheaply made, having the number twinkling bulbs reduced by 60% to just one in five, now being outnumbered by four times as many steady bulbs instead of being equal. These steady bulbs are the voltage that would be expected for the size of set or circuit, but still with 6-volt twinkle bulbs, and are available in larger sets like 70 and 100 (though not necessarily any longer than the older sets of 35 due to far shorter bulb spacing of today's cheap sets). Unlike the original sets, which frequently had different wedge bases on the two different bulb types to prevent too many sparkling bulbs from being used, modern sets generally do not enforce this with different sockets as there are so few twinkle bulbs to begin with.
LEDs also have twinkling versions, though they contain an oscillator that alternates on and off at a very regular intervals rather than the irregular blinking of the thermal bimetallic strips. Dimmers or low batteries generally do not affect the twinkling interval, but as with incandescent bulbs, having them off part of the time extends battery life.
LEDs start blinking immediately upon being turned on, but slight manufacturing differences mean the frequency is slightly off between them, and the LEDs soon appear semi-random when there are several together. Small groups may sometimes converge and then diverge again in the way that a group of cars may have turn signals briefly appear synchronized while waiting to turn.
Variations include ones which alternate back and forth between two colors, often red and green, or blue and white. These actually have two LEDs with the single transparent chip package. Others have a more advanced control within the LED that can vary the brightness like a candle flame, or fade between two or three colors, but these are not twinkle bulbs strictly speaking, and are often used individually instead of in strings.
Synchronized flashing or color changes with a control box are not due to twinkle bulbs, but LED ones may have two colors wired in inverse parallel within each bulb to respond to changes in electrical polarity (and voltage for brightness) from the control box.
The use of blinking LEDs requires a supply of direct current (DC) such as an electrical battery, as the unaltered alternating current (AC) causes the oscillator to constantly reset. To prevent this issue, mains-powered lights usually have a small rectifier or capacitor (or both) in the plugs to smooth the electricity, which also prevents the light set from flickering with the frequency of the electricity. Some twinkling LED bulbs are able to operate without this, instead doing the conversion internally.
An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxidation. Current is supplied to the filament by terminals or wires embedded in the glass. A bulb socket provides mechanical support and electrical connections.
Direct current (DC) is one-directional flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams. The electric current flows in a constant direction, distinguishing it from alternating current (AC). A term formerly used for this type of current was galvanic current.
A flashlight or torch is a portable hand-held electric lamp. Formerly, the light source typically was a miniature incandescent light bulb, but these have been displaced by light-emitting diodes (LEDs) since the mid-2000s. A typical flashlight consists of the light source mounted in a reflector, a transparent cover to protect the light source and reflector, a battery, and a switch, all enclosed in a case.
A dimmer is a device connected to a light fixture and used to lower the brightness of the light. By changing the voltage waveform applied to the lamp, it is possible to lower the intensity of the light output. Although variable-voltage devices are used for various purposes, the term dimmer is generally reserved for those intended to control light output from resistive incandescent, halogen, and compact fluorescent lamps (CFLs) and light-emitting diodes (LEDs). More specialized equipment is needed to dim fluorescent, mercury-vapor, solid-state, and other arc lighting.
Bicycle lighting is illumination attached to bicycles whose purpose above all is, along with reflectors, to improve the visibility of the bicycle and its rider to other road users under circumstances of poor ambient illumination. A secondary purpose is to illuminate reflective materials such as cat's eyes and traffic signs. A third purpose may be to illuminate the roadway so that the rider can see the way ahead. Serving the latter purposes require much more luminous flux and thus more power.
An emergency light is a battery-backed lighting device that switches on automatically when a building experiences a power outage.
The lighting system of a motor vehicle consists of lighting and signalling devices mounted to or integrated into the front, rear, sides, and in some cases the top of a motor vehicle. They illuminate the road ahead for the driver and increase the vehicle's visibility, allowing other drivers and pedestrians to see its presence, position, size, direction of travel, and its driver's intentions.
A test light, test lamp, voltage tester, or mains tester is a piece of electronic test equipment used to determine the presence of electricity in a piece of equipment under test. A test light is simpler and less costly than a measuring instrument such as a multimeter, and often suffices for checking for the presence of voltage on a conductor. Properly designed test lights include features to protect the user from accidental electric shock. Non-contact test lights can detect voltage on insulated conductors.
A thermal cutoff is an electrical safety device that interrupts electric current when heated to a specific temperature. These devices may be for one-time use, or may be reset manually or automatically.
Edison screw (ES) is a standard lightbulb socket for electric light bulbs. It was developed by Thomas Edison (1847–1931), patented in 1881, and was licensed in 1909 under General Electric's Mazda trademark. The bulbs have right-hand threaded metal bases (caps) which screw into matching threaded sockets. For bulbs powered by AC current, the thread is generally connected to neutral and the contact on the bottom tip of the base is connected to the "live" phase.
Aviation obstruction lighting is used to enhance the visibility of structures or fixed obstacles which may conflict with the safe navigation of aircraft. Obstruction lighting is commonly installed on towers, buildings, and even fences located in areas where aircraft may be operating at low altitudes. In certain areas, some aviation regulators mandate the installation, operation, color, and/or status notification of obstruction lighting. For maximum visibility and collision-avoidance, these lighting systems commonly employ one or more high-intensity strobe or LED devices which can be seen by pilots from many miles away from the obstruction.
A multifaceted reflector light bulb is a reflector housing format for halogen as well as some LED and fluorescent lamps. MR lamps were originally designed for use in slide projectors, but see use in residential lighting and retail lighting as well. They are suited to applications that require directional lighting such as track lighting, recessed ceiling lights, desk lamps, pendant fixtures, landscape lighting, retail display lighting, and bicycle headlights. MR lamps are designated by symbols such as MR16 where the diameter is represented by numerals indicating units of eighths of an inch. Common sizes for general lighting are MR16 and MR11, with MR20 and MR8 used in specialty applications. Many run on low voltage rather than mains voltage alternating current so require a power supply.
An automobile auxiliary power outlet in an automobile was initially designed to power an electrically heated cigarette lighter, but became a de facto standard DC connector to supply electrical power for portable accessories used in or near an automobile directly from the vehicle's electrical system. Such include mobile phone chargers, cooling fans, portable fridges, electric air pumps, and power inverters.
Holiday lighting technology has been subject to considerable development and variation since the replacement of candles by electric lights. While originally used during the Christmas holidays as Christmas lights, modern electric light arrays have become popular around the world in many cultures and are used both during religious festivals and for other purposes unconnected to any festivities.
LED art is a form of light art constructed from light-emitting diodes. LEDs are very inexpensive to purchase and have become a new way to make street art. Many artists who use LEDs are guerrilla artists, incorporating LEDs to produce temporary pieces in public places. LEDs may be used in installation art, sculptural pieces and interactive artworks.
The VRB-25 is a lighthouse optical system designed and built by Vega Industries Ltd. in Porirua, New Zealand. It was originally designed in 1993-95 with the assistance of the United States Coast Guard to meet USCG requirements for a robust mechanism requiring minimum maintenance. It has become the Coast Guard's standard 12 volt rotating beacon. The company's literature says there are more than 400 installations worldwide. More than a quarter of the active lighthouses in Maine have one installed.
A wedge base is a type of electrical connector used as a fitting for small light bulbs. It is similar to the bi-pin connector, except that the two "pins" are the same wires that extend into the bulb, and the wires are bent up onto the sides of the base, where they make contact with the socket. The wires are usually inserted into a plastic base that the bulb is mounted in, and which is often narrower at the tip than at the bulb, giving it a wedge shape and usually ensuring a tight connection, depending on manufacturing tolerances. Some bulbs have no plastic base, and the wires are simply bent up to the sides of the bulb's glass base.
A trouble light, also known as a rough service light, drop light, or inspection lamp, is a special lamp used to illuminate obscure places and able to handle moderate abuse. The light bulb is housed in a protective cage and a handle that are molded to form a single unit. It has a long power line for distant reaching; the handle may also have an electrical outlet on it, allowing the light to also double as an extension cord.
A 3-way lamp, also known as a tri-light, is a lamp that uses a 3-way light bulb to produce three levels of light in a low-medium-high configuration. A 3-way lamp requires a 3-way bulb and socket, and a 3-way switch. Unlike an incandescent lamp controlled by a dimmer, each of the filaments operates at full voltage, so the color of the light does not change between the three steps of light available. Certain compact fluorescent lamp bulbs are designed to replace 3-way incandescent bulbs, and have an extra contact and circuitry to bring about similar light level. In recent years, LED three way bulbs have become available as well.
A rope light is primarily used as a decorative lighting fixture, featuring small light bulbs linked together and encased in a PVC jacket to create a string of lights. Rope lights can be used in many applications both indoors and outdoors. Used in place of neon signs, it is sometimes called soft neon.