When replacing NiCd batteries in packs or portable tools, it is often necessary to attach wires to the individual cells. It may be possible to obtain NiCds with solder tabs attached (Radio Shack has these) but if yours do not, here are two ways that work. They both require a (Weller) high wattage soldering gun. I use a high power Weller (140 W) soldering gun. Use fine sandpaper to thoroughly clean and roughen up the surface of the battery cell at both ends. Tin the wires ahead of time as well. Arrange the wire and cell so that they are in their final position - use a vise or clamp or buddy to do this. Heat up the soldering gun but do not touch it to the battery until it is hot - perhaps 10 seconds. Then, heat the contact area on the battery end while applying solder. It should melt and flow quite quickly. As soon as the solder adheres to the battery, remove the heat without moving anything for a few seconds. Inspect and test the joint. A high power soldering iron can also be used. Here is a novel approach that appears to work: (From: Clifford Buttschardt (email@example.com)). There is really no great amount of danger spot welding tabs! They usually are made of pure nickel material. I put two sharp pointed copper wires in a soldering gun, place both on the tab in contact with the battery case and pull the trigger for a short burst. The battery remains cool. (From: firstname.lastname@example.org (Michael Covington)). Of course! A soldering gun is a source of about 1.5 V at 100 A RMS. Should make a fine spot-welder. You should write that up for QST ("Hints and Kinks") or better yet, send it in a letter to the editor of "Electronics Now" (the magazine I write for).
There is a graded width resistance element that gets connected when you pinch those two points. It heats up - substantially, BTW. Some sort of liquid crystal or other heat sensitive material changes from dark to clear or yellow at a fairly well defined temperature. Incidentally, since the current is significant, repeated 'testing' will drain the batteries - as with any proper under-load battery test! This isn't an issue for occasional testing but if the kids figure how to do this.... Personally, I would rather use a $3 battery checker instead of paying for throw-away frills!
Even where you have the AC adapter, it is quite likely that simply removing the (shorted) battery pack will not allow you to use it. This is because it probably uses the battery as a smoothing capacitor. You cannot simply replace the battery with a large electrolytic capacitor because the battery also limits the voltage to a value determined by the number of cells in the pack. Without it, the voltage would be much too high, possibly resulting in damage. You could use N power diodes in series (i.e., N=Vb/.7) to drop the approximate voltage of the battery pack AND a large capacitor but you would be wasting a lot of power in the form of heat. One alternative is to substitute a regulated power supply with an output equal to the the battery voltage and current capacity found by dividing the VA rating of the normal wall adapter by the battery's nominal terminal voltage (this will be worst case - actual requirements may be less). Connect this directly in place of the original battery pack. Unless there is some other sort of interlock, the equipment should be perfectly happy and think it is operating from battery power! Also see the chapter: "AC Adapters and Transformers".
Editor's note: More information on incandescent light bulbs can be found at: http://www.misty.com/~don/.
The basic incandescent lamp operates on the same basic principles as the original carbon filament lamp developed by Thomas Edison. However, several fundamental changes have made it somewhat more efficient and robust. However, modern bulbs are hardly efficient at producing lighte. Typically, only about 3 to 7 percent of the electrical energy used by a typical incandescent light bulb is turned into useful (visible) light. The rest goes to waste (usually) as heat. Tungsten replaced carbon as the filament material once techniques for working this very brittle metal were perfected (Edison knew about tungsten but had no way of forming it into fine wire). Most light bulbs are now filled with an inert gas rather than containing a vacuum like Edison's originals. This serves two purposes: it reduces filament evaporation and thus prolongs bulb life and reduces bulb blackening and it allows the filament to operate at a higher temperature and thus improves color and brightness. However, the gas conducts heat away so some additional power is wasted to heating the surroundings. Incandescent lamps come in all sizes from a fraction of a watt type smaller than a grain of wheat to a 75 KW monsters bulbs. In the home, the most common bulbs for lighting purposes are between 4 W night light bulbs and 250-300 W torch bulbs (floor standing pole lamps directing light upwards). For general use, the 60, 75, and 100 W varieties are most common. Recently, 55, 70 and 95 W 'energy saving' bulbs have been introduced. However, these are just a compromise between slightly reduced energy use and slightly less light. My recommendation: use compact fluorescents to save energy if these fit your needs. Otherwise, use standard light bulbs. Most common bases are the Edison medium (the one we all know and love) and the candelabra (the smaller style for night lights, chandeliers, and wall sconces. Three-way bulbs include two filaments. The three combinations of which filaments are powered result in low, medium, and high output. A typical 3-way bulb might be 50 (1), 100 (2), and 150 (1+2) W. If either of the filaments blows out, the other may still be used as a regular bulb. Unfortunately, 3-way bulbs do tend to be much more expensive than ordinary light bulbs. There may be adapters to permit a pair of normal bulbs to be used in a 3-way socket - assuming the space exists to do this safely (without scorching the shade). The base of a 3-way bulb has an additional ring to allow contact to the second filament. Inexpensive 3-way sockets (not to be confused with 3-way wall switches for operation of a built-in fixture from two different locations) allow any table lamp to use a 3-way bulb. Flashlight bulbs are a special category which are generally very small and run on low voltage (1.5-12 V). They usually have a filament which is fairly compact, rugged, and accurately positioned to permit the use of a reflector or lens to focus the light into a fixed or variable width beam. These usually use a miniature screw or flange type base although many others are possible. When replacing a flashlight bulb, you must match the new bulb to the number and type of battery cells in your flashlight. Automotive bulbs are another common category which come in a variety of shapes and styles with one or two filaments. Most now run on 12 V. Other common types of incandescent bulbs: colored, tubular, decorative, indoor and outdoor reflector, appliance, ruggedized, high voltage (130 V).
The lifespan of an average incandescent bulb is 750-1000 hours which is about 1.5 months if left on continuously or roughly 4 months if used 8 hours a day. So, if you are seeing a 3-4 month lifespan, this may not be that out of line depending on usage. With a lot of bulbs in a house, you may just think you are replacing bulbs quite often. Having said that, several things can shorted lamp life: 1. Higher than normal voltage - the lifespan decreases drastically for slight increases in voltage (though momentary excursions to 125 V, say, should not be significant). 2. Vibration - what is the fixture mounted in, under, or on? 3. High temperatures - make sure you are not exceeding the maximum recommended. wattage for your fixture(s). 4. Bad switches bad connections due to voltage fluctuations. If jiggling or tapping the switch causes the light to flicker, this is a definite possibility. Repeated thermal shock may weaken and blow the filament. A bad neutral connection at your electrical service entrance could result in certain circuits in your house having a higher voltage than normal - multimeter would quickly identify any. It may be possible to get your power company to put a recording voltmeter on your line to see if there are regular extended periods of higher than normal voltage - above 120 to 125 V. To confirm that the problem is real, label the light bulbs with their date (and possibly place of purchase or batch number - bad light bulbs are also a possibility). An indelible marker should be satisfactory. Of course, consider using compact or ordinary fluorescent lamps where appropriate. Use higher voltage (130 V) bulbs in hard to reach places. Bulbs with reinforced filament supports ('tuff bulbs') are also available where vibration is a problem.
(From: Don Klipstein (email@example.com)). A halogen bulb is an ordinary incandescent bulb, with a few modifications. The fill gas includes traces of a halogen, often but not necessarily iodine. The purpose of this halogen is to return evaporated tungsten to the filament. As tungsten evaporates from the filament, it usually condenses on the inner surface of the bulb. The halogen is chemically reactive, and combines with this tungsten deposit on the glass to produce tungsten halides, which evaporate fairly easily. When the tungsten halide reaches the filament, the intense heat of the filament causes the halide to break down, releasing tungsten back to the filament. This process, known as the halogen cycle, extends the life of the filament somewhat. Problems with uneven filament evaporation and uneven deposition of tungsten onto the filament by the halogen cycle do occur, which limits the ability of the halogen cycle to prolong the life of the bulb. However, the halogen cycle keeps the inner surface of the bulb clean. This lets halogen bulbs stay close to full brightness as they age. (recall how blackened an ordinary incandescent bulb can become near the end of its life --- sam). In order for the halogen cycle to work, the bulb surface must be very hot, generally over 250 degrees Celsius (482 degrees Fahrenheit). The halogen may not adequately vaporize or fail to adequately react with condensed tungsten if the bulb is too cool. This means that the bulb must be small and made of either quartz or a high-strength, heat-resistant grade of glass known as "hard glass". Since the bulb is small and usually fairly strong, the bulb can be filled with gas to a higher pressure than usual. This slows down the evaporation of the filament. In addition, the small size of the bulb sometimes makes it economical to use premium fill gases such as krypton and xenon instead of the cheaper argon. The higher pressure and better fill gases can extend the life of the bulb and/or permit a higher filament temperature that results in higher efficiency. Any use of premium fill gases also results in less heat being conducted from the filament by the fill gas, meaning more energy leaves the filament by radiation, meaning a slight improvement in efficiency.
A halogen bulb is often 10 to 20 percent more efficient than an ordinary incandescent bulb of similar voltage, wattage, and life expectancy. Halogen bulbs may also have two to three times as long a lifetime as ordinary bulbs, sometimes also with an improvement in efficiency of up to 10 percent. How much the lifetime and efficiency are improved depends largely on whether a premium fill gas (usually krypton, sometimes xenon) or argon is used. Halogen bulbs usually fail the same way that ordinary incandescent bulbs do, usually from melting or breakage of a thin spot in an aging filament. Thin spots can develop in the filaments of halogen bulbs, since the filaments can evaporate unevenly and the halogen cycle does redeposit evaporated tungsten in a perfect, even manner nor always in the parts of the filament that have evaporated the most. However, there are additional failure modes which result in similar kinds of filament degradation. It is generally not a good idea to touch halogen bulbs, especially the more compact, hotter-running quartz ones. Organic matter and salts are not good for hot quartz. Organic matter such as grease can carbonize, leaving a dark spot that absorbs radiation from the filament and becomes excessively hot. Salts and alkaline materials (such as ash) can sometimes "leach" into hot quartz, which typically weakens the quartz, since alkali and alkaline earth metal ions are slightly mobile in hot glasses and hot quartz. Contaminants may also cause hot quartz to crystallize, weakening it. Any of these mechanisms can cause the bulb to crack or even violently shatter. For this reason, halogen bulbs should only be operated within a suitable fully enclosed fixture. If a quartz halogen bulb is touched, it should be cleaned with alcohol to remove any traces of grease. Traces of salt will also be removed if the alcohol has some water in it.
Dimming a halogen bulb, like dimming any other incandescent lamp, greatly slows down the formation of thin spots in the filament due to uneven filament evaporation. However, "necking" of the ends of the filament remains a problem. If you dim halogen lamps, you may need "soft-start" devices in order to achieve a major increase in bulb life. Another problem with dimming of halogen lamps is the fact that the halogen cycle works best with the bulb and filament at or near specific optimum temperatures. If the bulb is dimmed, the halogen may fail to "clean" the inner surface of the bulb. Or, tungsten halide that results may fail to return tungsten to the filament. Halogen bulbs should work normally at voltages as low as 90 percent of what they were designed for. If the bulb is in an enclosure that conserves heat and a "soft-start" device is used, it will probably work well at even lower voltages, such as 80 percent or possibly 70 percent of its rated voltage. Dimmers can be used as soft-start devices to extend the life of any particular halogen bulbs that usually fail from "necking" of the ends of the filament. The bulb can be warmed up over a period of a couple of seconds to avoid overheating of the "necked" parts of the filament due to the current surge that occurs if full voltage is applied to a cold filament. Once the bulb survives starting, it is operated at full power or whatever power level optimizes the halogen cycle (usually near full power). The dimmer may be both "soft-starting" the bulb and operating it at slightly reduced power, a combination that often improves the life of halogen bulbs. Many dimmers cause some reduction in power to the bulb even when they are set to maximum. (A suggestion from someone who starts expensive medical lamps by turning up a dimmer and reports major success in extending the life of expensive special bulbs from doing this.)
Also see the document: "Engineering, Science, and Other (Pretty Clean) Jokes Collection" for all the light bulb jokes you could never want. (From: Susanne Shavelson (firstname.lastname@example.org)). People have often mentioned experiencing epidemics of light-bulb-death after moving into a new (to them) house. The same thing happened to us for a few months after moving last year into a 55-year-old house. After most of the bulbs had been replaced, things settled down. I am persuaded by the theory advanced by David (?) Owen in his wonderfully informative and witty book "The Walls Around Us" that houses undergo a sort of nervous breakdown when a new occupant moves in, leading to all sorts of symptoms like blown bulbs, plumbing problems, cracks in the walls, and so forth. Now that the house has become more accustomed to us, the rate at which strange phenomena are occurring has slowed.
These are usually either Negative Temperature Coefficient (NTC) thermisters or simple diodes. When cold, NTC thermisters have a high resistance. As they warm up, the resistance decreases so that the current to the light bulb is ramped up gradually rather than being applied suddenly. With a properly selected (designed) thermistor, I would not expect the light output to be affected substantially. However, while reducing the power on surge may postpone the death of the bulb, the filament wear mechanism is due to evaporation and redeposition of the tungsten during normal operation. This is mostly a function of the temperature of the filament. A thermistor which was not of low enough hot resistance would be dissipating a lot of power - roughly .8 W/volt of drop for a 100W bulb. Any really substantial increase in bulb life would have to be due to this drop in voltage and not the power-on surge reduction. The bulb saver (and socket) would also be heating significantly. The bulb savers that are simply diodes do not have as much of a heat dissipation problem but reduce the brightness substantially since the bulbs are running at slightly over half wattage. Not surprisingly, the life does increase by quite a bit. However, they are less efficient at producing light at the lower wattage and it is more orange. If you are tempted to then use a higher wattage bulb to compensate, you will ultimately pay more than enough in additional electricity costs to make up for the longer lived bulbs. My recommendation: use high efficiency fluorescents where practical. Use 130 V incandescents if needed in hard to reach places where bulb replacement is a pain. Stay away from bulb savers, green plugs, and other similar products claiming huge energy reduction. Your realized savings for these products will rarely approach the advertised claims and you risk damage to your appliances with some of these.
No, sorry, I don't have conclusive proof. I would love to be proved wrong - I could save a lot on light bulbs. However, new bulbs do not fail upon power on. Old bulbs do. If you examine the filament of a well worn light bulb, you will see a very distinct difference in surface appearance compared to a brand new one. The surface has gone from smooth to rough. This change is caused by sustained operation at normal light bulb temperatures resulting in unequal evaporation of the filament. Reducing the power on surge with a thermistor will reduce the mechanical shock which will postpone the eventual failure. 5X or even 20 % increase in life is pushing it IMHO. I do believe that Consumer Reports has tested these bulb savers with similar conclusions (however, I could be mistaken about the kind of bulb savers they tested - it was quite awhile ago).
Editor's note: This section is a condensed version of the document of the same name available at: http://www.misty.com/~don/. Special thanks to Don Klipstein for help in editing of this material.
The fluorescent lamp was the first major advance to be a commercial success in small scale lighting since the tungsten incandescent bulb. Its greatly increased efficiency resulted in cool (temperature wise) brightly lit workplaces (offices and factories) as well as home kitchens and baths. The development of the mercury vapor high intensity discharge (HID) lamp actually predates the fluorescent (the latter being introduced commercially in 1938, four years after the HID). However, HID type lamps have only relatively recently become popular in small sizes for task lighting in the home and office; yard and security area lighting; and light source applications in overhead, computer, and video projectors. Fluorescent lamps are a type of gas discharge tube similar to neon signs and mercury or sodium vapor street or yard lights. A pair of electrodes, one at each end - are sealed along with a drop of mercury and some inert gases (usually argon) at very low pressure inside a glass tube. The inside of the tube is coated with a phosphor which produces visible light when excited with ultra-violet (UV) radiation. The electrodes are in the form of filaments which for preheat and rapid or warm start fixtures are heated during the starting process to decrease the voltage requirements and remain hot during normal operation as a result of the gas discharge (bombardment by positive ions). When the lamp is off, the mercury/gas mixture is non-conductive. When power is first applied, a high voltage (several hundred volts) is needed to initiate the discharge. However, once this takes place, a much lower voltage - usually under 100 V is needed to maintain it. The electric current passing through the low pressure gases (mainly the mercury vapor) emits quite a bit of UV (but not much visible light). The internal phosphor coating very efficiently converts most of the UV to visible light. The mix of the phosphor(s) is used to tailor the light spectrum to the intended application. Thus, there are cool white, warm white, colored, and black light fluorescent (long wave UV) lamps. There are also lamps intended for medical or industrial uses with a special envelope that passes short wave UV radiation such as quartz. Some have an uncoated envelope, and emit short-wave UV mercury radiation. Others have phosphors that convert shortwave UV to medium wave UV. CAUTION: many of these emit shortwave or medium wave UV which is harmful and should not be used without appropriate protection in an enclosure which prevents the escape of harmful UV radiation. Fluorescent lamps are about 2-4 times as efficient as incandescent lamps at producing light at the wavelengths that are useful to humans. Thus, they run cooler for the same effective light output. The bulbs themselves also last a lot longer - 10,000 to 20,000 hours vs. 1000 hours for a typical incandescent. However, for certain types of ballasts, this is only achieved if the fluorescent lamp is left on for long periods of time without frequent on-off cycles.
The actual fluorescent tubes are identified by several letters and numbers and will look something like 'F40CW-T12' or 'FC12-T10'. So, the typical labeling is of the form FSWWCCC-TDD (variations on this format are possible): F - Fluorescent lamp. S - Style - no letter indicates normal straight tube; C for Circline. WW - Nominal power in Watts. 4, 5, 8, 12, 15, 20, 30, 40, etc. CCC - Color. W=White, CW=Cool white, WW=Warm white, BL/BLB=Black light, etc. T - Tubular bulb. DD - Diameter of tube in of eighths of an inch. T8 is 1", T12 is 1.5", etc. For the most common T12 (1.5 inch) tube, the wattage (except for newer energy saving types) is usually 5/6 of the length in inches. Thus, an F40-T12 tube is 48 inches long.
The compact fluorescent lamp is actually a fairly conventional fluorescent tube packaged with an integral ballast (either iron or electronic) in a standard screw base that can be installed into nearly any table lamp or lighting fixture. These types are being heavily promoted as energy savings alternatives to incandescent lamps. They also have a much longer life - up to 20,000 hours compared to 750 to 1000 hours for a standard incandescent. While these basic premises are not in dispute - all is not peaches and cream: 1. They are often physically larger than the incandescent bulbs they replace and simply may not fit the lamp or fixture conveniently or at all. 2. The funny elongated or circular shape may result in a less optimal lighting pattern. 3. The light is generally cooler - less yellow - than incandescents - this may be undesirable and result in less than pleasing contrast with ordinary lamps and ceiling fixtures. Newer models have been addressing this issue. 4. Some types (usually iron ballasts) may produce an annoying 120 Hz (or 100 Hz) flicker. 5. Ordinary dimmers cannot be used with compact fluorescents. 6. Like other fluorescents, operation at cold temperatures (under 50 degrees F) may be erratic. 7. There may be am audible buzz from the ballast. 8. They may produce Radio Frequency Interference (RFI). 9. The up-front cost is substantial (unless there is a large rebate): $10 to $20 for a compact fluorescent to replace a 60 W incandescent bulb! 10. Due to the high up-front cost, the pay-back period may approach infinity. 11. While their life may be 20,000 hours, a wayward baseball will break one of these $10 to $20 bulbs as easily as a 25 cent incandescent. Nonetheless, due to the lower energy use and cooler operation, compact fluorescents do represent a desirable alternative to incandescents. Just don't open that investment account for all your increased savings just yet!
The typical fixture consists of: * Lamp holder - the most common is designed for the straight bipin base bulb. The 12, 15, 24, and 48 inch straight fixtures are common in household and office use. The 4 foot (48") type is probably the most widely used size. U shaped, circular (Circline(tm)), and other specialty tubes are also available. * Ballast(s) - these are available for either 1 or 2 lamps. Fixtures with 4 lamps usually have two ballasts. See the sections below on ballasts. The ballast performs two functions: current limiting and providing the starting kick to ionize the gas in the fluorescent tube(s). * Switch - on/off control unless connected directly to building wiring in which case there will be a switch or relay elsewhere. The power switch may have a momentary 'start' position if there is no starter and the ballast does not provide this function. * Starter (preheat fixtures only) - device to initiate the high voltage needed for starting. In other fixture types, the ballast handles this function.
For a detailed explanation, check your library. Here is a brief summary. A ballast serves two functions: 1. Provide the starting kick. 2. Limit the current to the proper value for the tube you are using. In the old days fluorescent fixtures had a starter or a power switch with a 'start' position which is in essence a manual starter. Some cheap ones still do use this technology. The starter is a time delay switch which when first powered, allows the filaments at each end of the tube to warm up and then interrupts this part of the circuit. The inductive kick as a result of interrupting the current through the inductive ballast provides enough voltage to ionize the gas mixture in the tube and then the current through the tube keeps the filaments hot - usually. You will notice that a few iterations are sometimes needed to get the tube to light. The starter may keep cycling indefinitely if either it or one of the tubes is faulty. While the lamp is on, a preheat ballast is just an inductor which at 60 Hz (or 50 Hz) has the appropriate impedance to limit the current to the tube(s) to the proper value. Ballasts must generally be fairly closely matched to the lamp in terms tube wattage, length, and diameter.
Instant start, trigger start, rapid start, etc. ballasts include loosely coupled high voltage windings and other stuff and do away with the starter: 1. The ballast for a preheat fixture (using a starter or power switch with a 'start' position) is basically a series inductor. Interrupting current through the inductor provides the starting voltage. 2. The ballast for an instant start fixture has a loosely coupled high voltage transformer winding providing about 500-600 V for starting in addition to the series inductor. 3. The ballast for a rapid start fixture has in addition small windings for heating the filaments reducing the required starting voltage to 250-400 V. Trigger start fixtures are similar to rapid start fixtures. Starting voltage is either provided by the inductive kick upon interruption of the current bypassed through the starter for (1) or a high voltage winding in (2) and (3). In all cases, the current limiting is provided primarily by the impedance of the series inductance at 60 Hz (or 50 Hz depending on where you live).
These devices are basically switching power supplies that eliminate the large, heavy, 'iron' ballast and replace it with an integrated high frequency inverter/switcher. Current limiting is then done by a very small inductor, which has sufficient impedance at the high frequency. Properly designed electronic ballasts should be very reliable. Whether they actual are reliable in practice depends on their location with respect to the heat produced by the lamps as well as many other factors. Since these ballasts include rectification, filtering, and operate the tubes at a high frequency, they also usually eliminate or greatly reduce the 120 Hz flicker associated with iron ballasted systems. I have heard, however, of problems with these relating to radio frequency interference from the ballasts and tubes. Other complaints have resulted do to erratic behavior of electronic equipment using infra red remote controls. There is a small amount of IR emission from the fluorescent tubes themselves and this ends up being pulsed at the inverter frequencies which are similar to those used by IR hand held remote controls.
The following is the circuit diagram for a typical preheat lamp - one that uses a starter or starting switch. Power Switch +-----------+ Line 1 (H) o------/ ---------| Ballast |------------+ +-----------+ | | .--------------------------. | Line 2 (N) o---------|- Fluorescent -|-----+ | ) Tube ( | +---|- (bipin) -|-----+ | '--------------------------' | | | | +-------------+ | | | Starter | | +----------| or starting |-----------+ | switch | +-------------+ Here is a variation that some preheat ballasts use. This type was found on a F13-T5 lamp fixture: Power Switch +-------------+ Line 1 (H) o------/ --------|A Ballast | +----------|B C|-----------+ | +-------------+ | | | | .--------------------------. | Line 2 (N) o-----+---|- Fluorescent -|-----+ | ) Tube ( | +---|- (bipin) -|-----+ | '--------------------------' | | | | +-------------+ | | | Starter | | +----------| or starting |-----------+ | switch | +-------------+
The starter incorporates a switch which is normally open. When power is applied a glow discharge takes place which heats a bimetal contact. A second or so later, the contacts close providing current to the fluorescent filaments. Since the glow is extinguished, there is no longer any heating of the bimetal and the contacts open. The inductive kick generated at the instant of opening triggers the main discharge in the fluorescent tube. off with the contacts open. If the contacts open at a bad time - current near zero, there isn't enough inductive kick and the process repeats. Where a manual starting switch is used instead of an automatic starter, there will be three switch positions: OFF: Both switches are open. ON: Power switch is closed. START: (momentary) Power switch remains closed and starting switch in closed. When released from the start position, the breaking of the filament circuit results in an inductive kick as with the automatic starter which initiates the gas discharge.
Rapid start and trigger start fixtures do not have a separate starter or starting switch but use auxiliary windings on the ballast for this function. The rapid start is now most common though you may find some labeled trigger start as well. Trigger start ballasts seem to be used for 1 or 2 small (12-20 W tubes). Basic operation is very similar to that of rapid start ballasts and the wiring is identical. The ballast includes separate windings for the filaments and a high voltage starting winding that is on a branch magnetic circuit that is loosely coupled to the main core and thus limits the current once the arc is struck. A reflector grounded to the ballast (and power wiring) is often required for starting. The capacitance of the reflector aids in initial ionization of the gases. Lack of this connection may result in erratic starting or the need to touch or rum the tube to start. A complete wiring diagram is usually provided on the ballast's case. Power is often enabled via a socket operated safety interlock (x-x) to minimize shock hazard. However, I have seen normal (straight) fixtures which lack this type of socket even where ballast labeling requires it. Circline fixtures do not need an interlock since the connectors are fully enclosed - it is not likely that there could be accidental contact with a pin while changing bulbs. Below is the wiring diagram for a single lamp rapid or trigger start ballast. The color coding is fairly standard. The same ballast could be used for an F20-T12, F15-T12, F15-T8, or F14-T12 lamp. A similar ballast for a Circline fixture could be used with an FC16-T10 or lamp FC12-T10 (no interlock). +--------------------------+ Line 2 (N) o----------------|Black Rapid/Trigger | +-----|White Start Red|-----+ | +--|Blue Ballast Red|--+ | | | +-------------+------------+ | | | | | | | | | Grounded | Reflector | | | | ----------+---------- | | | | .----------------------. | | | +----|- Fluorescent -|----+ | +------x| ) Tube ( | | Line 1 (H) o----/ -----------x|- (bipin or circ.) -|-------+ Power Switch '----------------------' The following wiring diagram is for one pair (from a 4 tube fixture) of a typical rapid start 48 inch fixture. These ballasts specify the bulb type to be F40-T12 RS. There is no safety interlock on this fixture. Power Switch +--------------------------+ Line 1 (H) o----/ ----------|Black Dual Tube Red|-----------+ Line 2 (N) o----------------|White Rapid Red|--------+ | +-----|Yellow Start Blue|-----+ | | | +--|Yellow Ballast Blue|--+ | | | | | +-------------+------------+ | | | | | | | | | | | | | Grounded | Reflector | | | | | | ----------+---------- | | | | | | .----------------------. | | | | | +----|- Fluorescent -|----+ | | | | | | ) Tube 1 ( | | | | +-------|- bipin -|-------+ | | | | '----------------------' | | | | .----------------------. | | | +----|- Fluorescent -|----------+ | | | ) Tube 2 ( | | +-------|- bipin -|-------------+ '----------------------'Go to [Next] segment
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