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444:") were then introduced. While they are still nearly as large as rheostat dimmers, which they closely resemble, they are relatively efficient devices. Their voltage output, and so their dimming effect, is largely independent of the load applied so it was far easier to design the lighting that would be attached to each autotransformer channel. Remote control of the dimmers was still impractical, although some dimmers were equipped with motor drives that could slowly and steadily reduce or increase the brightness of the attached lamps. Autotransformers have fallen out of use for lighting but are used for other applications.
600:
469:
704:. A patch bay usually sits next to the dimmers enabling the dimmers to be connected to specific circuits via a patch cable. The patch bay may also enable many circuits to be connected to one dimmer and even series connection for low-voltage lamps. Also in some theatres individual cables are run directly from the light to dimmer. The assigned connections between the circuits (either at the patch bay or in the form of individual cables) and the dimmers is known as the
808:
the red trace. Typically it is measured in tens to hundreds of microseconds. A longer rise time reduces the noise of the dimmer and the lamp as well as extending the life of the lamp. A longer rise time also reduces the electromagnetic interference produced by the dimmer. Unsurprisingly, a longer rise time is more expensive to implement than a short one, this is because the size of choke has to be increased. Newer dimming methods can help minimize such problems.
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desires; they may have a choice between a linear relationship and selection of different curves, so that they can be matched with older analogue dimmers. Sophisticated systems provide user-programmable or nonstandard curves, and a common use of a nonstandard curve is to turn a dimmer into a "non-dim", switching on at a user defined control level.
395:; the liquid between a movable and fixed contact provided a variable resistance. The closer the contacts to each other, the more voltage was available for the light. Salt water dimmers required regular addition of water and maintenance due to corrosion; exposed parts were energized during operation, presenting a shock hazard.
531:(SCR) dims the light through phase-angle control. This unit is wired in series with the load. Diodes (D2, D3, D4 and D5) form a bridge, which generates pulsed DC. R1 and C1 form a circuit with a time constant. As the voltage increases from zero (at the start of every halfwave) C1 charges up. When C1 is able to make
807:
One measure of the quality of a leading edge dimmer is the "rise time". The rise time in this context is the amount of time it takes for the cut part of the waveform to get from zero to the instantaneous output voltage. In the waveform above it is a measure of the slope of the almost vertical edge of
551:
Waveform of the output voltage of a thyristor dimmer set for 60 volts RMS output, with 120 V input. The red trace shows the output device switching on about 5.5 ms after the input (blue) voltage crosses zero. Switching the thyristor on earlier in each half cycle gives a higher output
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as "singing". The suppression circuitry might be insufficient to prevent buzzing to be heard on sensitive audio and radio equipment that shares the mains supply with the lighting loads. In this case, special steps must be taken to prevent this interference. European dimmers must comply with relevant
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were inefficient since they would dissipate a significant portion of the power rating of the load as heat. They were large and required plenty of cooling air. Because their dimming effect depended a great deal on the total load applied to each rheostat, the load needed to be matched fairly carefully
255:
In the professional lighting industry, changes in intensity are called "fades" and can be "fade up" or "fade down". Dimmers with direct manual control had a limit on the speed they could be varied at but this problem has been largely eliminated with modern digital units (although very fast changes in
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In less advanced systems, this same effect is achieved by literally pre-heating (warming) the globes before an event or performance. This is usually achieved by slowly bringing the lights up to full (or usually 90-95%) power over a period of between 1/2 to 1 hour. This is as effective as a built-in
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Television often uses a "square law" curve, providing finer control in top part of the curve, essential to allow accurate trimming of the colour temperature of lighting. Theatrical dimmers tend to use a softer "S" or linear curve. Digital dimmers can be made to have whatever curve the manufacturer
535:
D6 conduct and inject current into the SCR, the SCR fires. When the SCR conducts, D1 discharges C1 through the SCR. The SCR shuts off when the current falls to zero and the supply voltage drops at the end of the half cycle, ready for the circuit to start work on the next half cycle. This circuit is
411:
The coil-rotation transformer used a fixed-position electromagnet coil in conjunction with a variable-position coil to vary the voltage in the line by varying the alignment of the two coils. Rotated 90 degrees apart, the secondary coil is affected by two equal but opposite fields from the primary,
732:
The design of most analogue dimmers meant that the output of the dimmer was not directly proportional to the input. Instead, as the operator brought up a fader, the dimmer would dim slowly at first, then quickly in the middle, then slowly at the top. The shape of the curve resembled that of the
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effective value. Because they switch instead of absorbing part of the voltage supplied, there is very little wasted power. Dimming can be almost instantaneous and is easily controlled by remote electronics. This development also made it possible to make dimmers small enough to be used in place
274:
Most recently, software programmable internal dimmers can use signals from the same switch that turns lights on and off to control dimming. No dedicated external dimmer is needed. A simple communications protocol, such as Blink'n'Dim, delivers dimming commands via the power line. They enable
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function. This sets a minimum level, usually between 5% and 10%, which appears turned-off, but stops the lamp from cooling down too much. This also speeds up the lamp's reaction to sudden bursts of power that operators of rock'n'roll-style shows appreciate. The opposite of this function is
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Modern dimmer designs use microprocessors to convert the digital signal directly into a control signal for the switches. This has many advantages, giving closer control over the dimming, and giving the opportunity for diagnostic feedback to be sent digitally back to the lighting controller.
447:
However, there are certain lighting scenarios in which autotransformers are still a desirable solution (as of 2021). For instance, the control room of an audio recording studio may require an extremely strict limit for electromagnetic interference. In comparison with solid-state dimmers, the
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Early dimmers were directly controlled through the manual manipulation of large dimmer panels. This required all power to come through the lighting control location, which could be inconvenient, inefficient and potentially dangerous for large or high-powered systems, such as those used for
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However venues such as theatres demand more flexibility. To allow for changes for each show, and occasionally during shows, theatres sometimes install circuits run permanently to sockets around the theatre. Instead of these circuits going directly to the dimmer they are connected to a
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Dimmers are usually arranged together in racks, where they can be accessed easily, and then power is run to the instruments being controlled. In architectural installations electricity is run straight from the dimmers to the lights via permanent wiring (this is called a
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systems) became feasible. The wire for the control systems was much smaller (with low current and lower danger) than the heavy power cables of previous lighting systems. Each dimmer had its own control wires, resulting in many wires leaving the lighting control location.
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Modern digital desks can emulate preheat and dimmer curves and allow a soft patch to be done in memory. This is often preferred as it means that the dimmer rack can be exchanged for another one without having to transfer complicated settings. Many different curves, or
483:, dimmers were introduced to solve some of these problems. Semiconductor dimmers switch on at an adjustable time (phase angle) after the start of each alternating-current half-cycle, thereby altering the voltage waveform applied to lamps and so changing its
628:
In the late 70s, serial analogue protocols were developed. These multiplexed a series of analogue levels onto a single wire, with embedded clocking signal similar to a composite video signal (in the case of Strand
Lighting's European
314:
in 1961, invented a dimmer based on a then-new solid state switching device called a
Silicon Controlled Rectifier or SCR. This small device allowed the dimmer to be installed in a standard electrical wall box while saving energy.
625:. Some analogue circuitry then derives a control signal from this and the mains supply for the switches. As more channels are added to the system more wires are needed between the lighting controller and the dimmers.
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as used in an electric motor, except that the rotor was held against rotation using brakes and was moved to specific positions using high-torque gearing. Because the rotor did not ever turn a complete revolution, a
271:. Since semiconductor or solid-state dimmers switch quickly between a low resistance "on" state and a high resistance "off" state, they dissipate very little power compared with the controlled load.
648:, which sat next to the dimmers. This converted the digital signal into a collection of 0 to +10 V or 0 to −10 V signals which could be connected to the individual analogue control circuits.
275:
computer control via networked switches, but do not require it. Their cost is about the same as the older "dimmability" circuitry that they replace in LED bulbs, fixtures or drivers.
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in Europe) and the sudden surge of power causes the coils on the inductor to move, creating a buzzing sound associated with some types of dimmer; this same effect can be heard in the
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patented his "Safety Dimmer", which greatly reduced wasted energy by reducing the amount of energy generated to match desired demand rather than burning off unwanted energy.
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Non domestic dimmers are usually controlled remotely by means of various protocols. Analogue dimmers usually require a separate wire for each channel of dimming carrying a
322:. To house this device, he decided on a 2-inch round device with one end capable of being screwed into a light bulb socket and the other end able to receive a light bulb.
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Most modern fixed installations do not have patch bays; instead they have a dimmer-per-circuit, and patch dimmers into channels using a computerised control console's
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to the power rating of the rheostat. Finally, as they relied on mechanical control they were slow and it was difficult to change many channels at a time.
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A residential-type dimmer switch with sliding knob to change brightness. The device is small enough to fit into a regular wall box provided for a switch.
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third quarter of a sine wave. Different dimmers produced different dimmer curves, and different applications typically demanded different responses.
507:
are used as part of the circuitry to suppress this interference. When the dimmer is at 50% power, the switches are switching their highest voltage
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Switching high-intensity incandescent (filament) lamps to full power from cold can shorten their life dramatically, owing to the large
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Patching is the physical ("hard patch") or virtual ("soft patch") assignment to a circuit or channel for the purpose of control.
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have proved to be the answer since the late 80s. In early implementations a digital signal was sent from the controller to a
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In 1966, Eugene
Alessio patented a light bulb socket adapter for adjusting a light level on a single light bulb using a
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A dimmer rack containing 192 dimmers, with one dimmer per circuit. The black box at the upper left is a demultiplexer.
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legislation requirements; this involves suppressing the emissions described above to limits described in EN55104.
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installations. Small domestic dimmers are generally directly controlled, although remote control systems (such as
712:. This is most common in older theatres, and on a tour where dimmers will be brought in by the touring company.
57:
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240:) are available. Modern professional dimmers are generally controlled by a digital control system like
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enable the control of a large number of dimmers (and other stage equipment) through a single cable.
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Some dimmers in residential applications are also equipped with a radio receiver to be used as
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of the light output. Although variable-voltage devices are used for various purposes, the term
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standard, handling 384 dimmers) or separate clocking signal (in the case of the US standard
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Two 6000 watt motor driven autotransformer dimmers, used for theatre auditorium lighting
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768:. This limits the maximum power supplied to a lamp, which can also extend its life.
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904:"Lutron Electronics Donates Company History to National Museum of American History"
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which effectively cancel each other out and produce no voltage in the secondary.
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When solid-state dimmers came into use, analog remote control systems (such as
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was not required and long flexible cables could be used on the rotor instead.
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by chopping off the falling side of the sine wave. These circuits are called
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that occurs. To reduce stress on the lamp filaments, dimmers may have a
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conducted emissions produced by autotransformers are effectively zero.
248:. In newer systems, these protocols are often used in conjunction with
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Fading Lights. Transitions in theatre lighting in a historical context
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In the electrical schematic shown, a typical light dimmer based on a
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The switches generate some heat during switching and can also cause
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Early examples of a rheostat dimmer include a salt water dimmer or
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brightness may still be avoided for other reasons like lamp life).
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267:. A variable resistor would dissipate power as heat and acts as a
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This article is about the device. For the New
Zealand band, see
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An electrical schematic for a typical SCR-based light dimmer
228:
Dimmers range in size from small units the size of domestic
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Die Vierte Wand. Organ der
Initiative TheaterMuseum Berlin
1006:
http://www.lutron.com/TechnicalDocumentLibrary/360484.pdf
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which can be remotely controlled by a radio transmitter.
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instead of variable resistors, because they have higher
1085:
Lighting the Stage. Art and
Practice, Third Edition
784:
Example of an "S" curve a lightboard can soft patch
341:, or one of the many Ethernet-based protocols like
60:. Unsourced material may be challenged and removed.
799:can be programmed and used on different channels.
560:(IGBTs) do away with most of the noise present in
575:An even newer, but still expensive technology is
174:applied to the lamp, it is possible to lower the
1148:
232:to high-power units used in large theatrical or
209:). More specialized equipment is needed to dim
1091:, Broadway Press, Inc., Louisville Kentucky,
1089:Chapter 4 –The Control Console
932:"Patent US3452215 - Light bulb socket adapter"
333:More recent digital control protocols such as
696:). They are hard run and cannot be changed.
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182:is generally reserved for those intended to
603:Dimmer in a residential application with
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120:Learn how and when to remove this message
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579:, which is implemented as a high-power
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1142:Dimmers, Switchbanks & Efficiency
492:) of normal domestic light switches.
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136:A common dual dimmer module used in
58:adding citations to reliable sources
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918:"Patent US3032688 - Dimming device"
415:These coils resembled the standard
13:
558:insulated-gate bipolar transistors
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14:
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23:. For the hamlet in England, see
1060:"How Do Lighting Controls Work?"
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890:"Patent US569443 - Granville t"
45:needs additional citations for
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259:Modern dimmers are built from
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1110:. 009/2019, p. 128–139 (
1062:. HeathCo LLC. Archived from
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1083:Bellman, Wilard F. (2001).
946:"Open Lighting Architecture"
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552:voltage and brighter lights.
529:silicon-controlled rectifier
497:radio-frequency interference
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1102:Van Goethem, Chris (2019).
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640:Digital protocols, such as
155:is a device connected to a
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1112:Online at Internet Archive
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679:A telephone-type patch bay
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581:switched-mode power supply
312:Lutron Electronics Company
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18:
985:"Lutron Electronics, Inc"
399:Coil-rotation transformer
199:compact fluorescent lamps
1018:"Strand Dimming Systems"
859:Lighting control console
790:Lighting control console
613:Lighting control console
1172:19th-century inventions
687:A slider type patch bay
657:wireless light switches
327:0-10 V lighting control
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583:followed by a filter.
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432:Autotransformer dimmer
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310:, who would found the
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234:architectural lighting
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159:and used to lower the
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1137:Light dimmer circuits
869:Wireless light switch
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745:Example dimmer curves
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570:reverse phase dimming
566:trailing-edge dimmers
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542:forward phase dimming
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203:light-emitting diodes
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1066:on 13 September 2014
54:improve this article
1157:American inventions
538:leading-edge dimmer
1123:2017-03-09 at the
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772:preheat function.
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452:Solid-state dimmer
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167:. By changing the
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16:Engineering device
1118:sound.whsites.net
1042:"Dimming Methods"
960:"Types of dimmer"
764:sometimes called
577:sine-wave dimming
556:Dimmers based on
387:Salt water dimmer
378:Dimmers based on
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906:. 28 April 2010.
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1048:on 2014-10-16.
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1068:. Retrieved
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64:
52:Please help
47:verification
44:
1070:6 September
533:Zener diode
477:Solid-state
464:dimmer rack
219:solid-state
211:fluorescent
201:(CFLs) and
1151:Categories
970:2010-01-21
876:References
722:Soft Patch
716:Soft patch
710:hard patch
671:Hard patch
623:0 and 10 V
611:See also:
509:(>325 V
426:commutator
265:efficiency
225:lighting.
161:brightness
80:newspapers
844:Heat sink
829:Compulite
803:Rise time
702:patch bay
536:called a
513:filaments
501:Inductors
462:thyristor
436:Variable
380:rheostats
306:In 1959,
299:In 1896,
188:resistive
176:intensity
1162:Lighting
1121:Archived
834:Derating
819:Avolites
812:See also
797:profiles
663:Patching
621:between
605:RF-based
490:pattress
355:Pathport
250:Ethernet
172:waveform
147:A dimmer
69:"Dimmer"
776:Digital
766:top-set
761:preheat
751:Preheat
694:circuit
619:voltage
587:Control
515:of the
359:ShowNet
343:Art-Net
287:History
195:halogen
169:voltage
163:of the
94:scholar
1095:
642:DMX512
635:AMX192
562:TRIACs
505:chokes
442:Variac
421:stator
347:ETCnet
335:DMX512
180:dimmer
153:dimmer
96:
89:
82:
75:
67:
1028:(PDF)
1021:(PDF)
824:Choke
706:mains
479:, or
417:rotor
363:KiNET
320:triac
165:light
101:JSTOR
87:books
1106:In:
1093:ISBN
1072:2014
419:and
351:sACN
339:DALI
246:DALI
207:LEDs
73:news
1087:,
708:or
637:).
631:D54
568:or
540:or
522:EMC
503:or
499:.
485:RMS
361:or
244:or
242:DMX
238:X10
223:arc
56:by
1153::
987:.
724:.
572:.
544:.
460:A
357:,
353:,
349:,
345:,
337:,
296:.
252:.
217:,
213:,
193:,
151:A
1114:)
1099:,
1074:.
973:.
948:.
934:.
920:.
892:.
205:(
123:)
117:(
112:)
108:(
98:·
91:·
84:·
77:·
50:.
27:.
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