Contents:
The objective is to be able to control a single fixture from multiple locations with the capability of dimming as well as just power on/off. The simple type of 3-way dimmers are just a normal dimmer with a 3-way instead of normal switch. This allows dimming control from only one location. The other switches in the circuit must be conventional 3-way or 4-way type. Connecting conventional dimmers in series - which is what such a hookup would require - will not really work properly. Only if one of the dimmers is set for full brightness, will the other provide full range control. Anywhere in between will result in strange behavior. The other dimmer may have a very limited range or it may even result in oscillations - periodic or chaotic variations in brightness. The safety and reliability of such an arrangement is also questionable. True 3 way dimmers do exist but use a more sophisticated implementation than just a normal dimmer and 3-way switch since this will not work with electronic control of lamp brightness. One approach is to have encoder knobs (similar to those in a PC mouse) or up/down buttons at each location which send pulses and direction info back to a central controller. All actions are then relative to the current brightness. A low cost microcontroller or custom IC could easily interface to a number, say up to 8 (a nice round number) - of control positions. The manufacturing costs of such a system are quite low but due to its specialty nature, expect that your cost will be substantially higher than for an equivalent non-dimmable installation. If control of intensity at only one of the locations is acceptable, a regular dimmer can be put in series with the common of one of the normal 3-way switches. However, your brightness will be set by that dimmer alone. See the section: "Typical dimmer schematics". An alternative is to use X-10 technology to implement this sort of capability. This would likely be more expensive than a dedicated multi-way switch control but is more flexible as well. X-10 transmits control information over the AC lines to select and adjust multiple addressable devices like lamps and appliances. However, for the adventurous, see the section: "Independent dimming from two locations - kludge #3251".
Here is a scheme which will permit dimming with independent control from two
locations. Each location will have a normal switch and a dimmer knob. The
toggle essentially selects local or remote but like normal 3-way switches, the
actual position depends on the corresponding setting of the other switch:
Location 1 Location 2
+--------+ 4-way SW 3-way SW
Hot o--+---| Dimmer |----o\ /o--------o\ +---------+
| +--------+ / \o----------| Fixture |------o Neutral
| +--o/ \o--------o Center +---------+ Shell
| | (brass) (silver)
| | +--------+
| +------------| Dimmer |--+
| +--------+ |
+---------------------------------------+
As usual, the brass screw on the fixture or outlet should be connected to the
Hot side of the wiring and the silver screw to the Neutral side.
The dimmers can be any normal knob or slide type with an off position.
Note that as drawn, you need 4 wires between switch/dimmer locations.
4-way switches are basically interchange devices - the connections
are either an X as shown or straight across. While not as common as
3-way switches, they are available in your favorite decorator colors.
If using Romex type cable in between the two locations, make sure to tape or
paint the ends of the white wires black to indicate that they may be Hot as
required by Code.
And, yes, such a scheme will meet Code if constructed using proper wiring
techniques.
No, I will not extend this to more than 2 locations!
Also see the section: "Controlling a fixture or outlet from multiple locations".
CAUTION: However, note that a dimmer should not be wired to control an
outlet since it would be possible to plug a device into the outlet which
might be incompatible with the dimmer resulting in a safety or fire hazard.
(From: Neil). Touch dimmers work in a couple of different ways, depending on the IC used. Simple ones, such as those in the cheap 'touch lamps' that you find for sale on market stalls, etc. normally have three or four preset brightness levels and an OFF setting, which are operated sequentially: touch once for full brightness, again to dim slightly, again to dim a bit more, etc, until the OFF setting is reached. The next touch will then bring the lamp to full brightness. The better (and more expensive) units, such as the touch dimmer switches that are sold as direct replacements for conventional light switches, are similar, but have many more steps. A single touch will usually bring the lamp to full brightness, while keeping your finger in contact with the touch plate will slowly dim the lamp. You just remove your finger when the lamp is at the required brightness level. Both kinds of touch dimmer have three basic parts; 1. A touch sensor - this normally works by picking up mains hum from the touch plate, and rectifying it in a high-gain amplifier. 2. A ramp generator - normally in the form of a digital counter with DAC output. 3. A mains power control element - Generally a thyristor or triac. In some designs, this is encapsulated within the IC, while in others it is a discrete component. Most touch dimmers can be operated by standard push-button switches as well as a touch plate, and many can be adapted for remote control. There are a number of specially designed IC's available for touch dimmers, notably the HT7704B ,a four-step device for touch lamps as described above, and the SLB0586A, which is the other kind, with facilities for remote control.
Due to the sharp edges on the power supplied by a cheap light dimmer, Radio Frequency Interference (RFI) may be conducted back down the wiring directly to other appliances and/or radiated through space as well. Effects will include noise bars in the picture on some TV channels and/or a buzz in the audio across portions of the AM radio band. Better light dimmers will include a bypass capacitor (e.g., .01 uF, 1KV) and a series inductor to suppress RFI but these components were often left off in basic models. The FCC has tightened up on their regulations around 1992 so replacing older dimmer switches with newer ones may be the easiest solution. Installing in-line power line filters may work but other options like replacing all your house wiring with metal conduit, or only listening to FM radio are probably not realistic!
It is very tempting to try using a common light dimmer to control devices using power transformers. Will this work? There really is no definitive answer. It is generally not recommended but that doesn't mean it won't work perfectly safely in many instances. However, in principle this may be dependent on what is on the secondary side - a transformer appears more inductive when it is lightly loaded - and on the design of your particular dimmer. It could blow the dimmer or result in the dimmer simply getting stuck at full power for some or all of the control range since the inductive load will cause the current to continue flowing even after the voltage has gone to zero and the thyristor should shut off. If it works reliably in your situations, then this is not a problem. Again, it may be load dependent. It probably will result in more audible noise from the transformer but this is probably harmless except to your sanity. The only safety issues I can think of and these relate to the transformer running hotter than normal as a result of core saturation. This might happen at certain settings if the thyristor is not switching at the same point on the positive and negative half cycles. There would be a net DC current flow through the transformer which is not good, If the thyristor were to fail in such a way that it only triggered on one half cycle, very large DC current could flow. However, a suitably rated fuse or circuit breaker and thermal cutout should handle both these situations. Note: If your dimmer uses an SCR instead of a triac, this will result in immediate and catastrophic failure. An SCR results in a DC output. However, full range dimmers usually use triacs. The bottom line: I cannot provide any guarantees.
Battery operated flashlights (torches for those on the other side of the Lake) and lanterns are among the simplest of appliances. We probably all have a box or drawer full of dead flashlights. The most common problem after dead batteries is very often damage due to leaky batteries. Even supposedly leak-proof batteries can leak. Batteries also tend to be prone to leaking if they are weak or dead. Therefore, it is always a good idea to remove batteries from any device if it is not to be used for a while. How to assure the batteries will be with the flashlight? Put them in separate plastic bags closed and fastened with a twist tie. Test the batteries with a multimeter - fresh Alkalines should measure 1.5 V. Any cell that measures less than about 1.2 V or so should be replaced as they will let you down in the end. On a battery tester, they should read well into the green region. Check the bulb with a multimeter on the ohms scale - a bad bulb will test open. Bulbs may fail from use just like any other incandescent lamp or from a mechanical shock - particularly when lit and hot. Replacement bulbs must be exactly matched to the number and type of batteries (cells). A type number is usually stamped on the bulb itself. There are special halogen flashlight bulbs as well - I do not really know how much benefit they provide. The switches on cheap flashlights are, well, cheaply made and prone to unreliable operation or total failure. Sometimes, bending the moving metal strip a bit so it makes better contact will help. Clean the various contacts with fine sandpaper or a nail file. If a flashlight has been damaged as a result of battery leakage, repair may be virtually impossible. High quality flashlights are another matter. Maglights(tm) and similar units with machined casings and proper switches should last a long time but the same comments apply to batteries - store them separately to avoid the possibility of damage from leakage. Keep a spare bulb with each of these - the specialty bulbs may be harder to find than those for common garbage - sorry - flashlights. Rechargeable flashlights include a NiCd or lead-acid battery (one or more cells in series) and the recharging circuitry either as part of the unit itself or as a plug-in wall adapter or charging stand. See the sections: "Battery chargers" and "Typical rechargeable flashlight schematics" for more information.
Here are circuit diagrams from several inexpensive rechargeable flashlights. These all use very 'low-tech' chargers so battery life may not be as long as possible and energy is used at all times when plugged into an AC outlet.
This one is typical of combined all-in-one units using a lead-acid battery
that extends a pair of prongs to directly plug into the wall socket for
charging.
It is a really simple, basic charger. However, after first tracing out the
circuit, I figured only the engineers at First Alert knew what all the diodes
were for - or maybe not :-). But after some reflection and rearrangement of
diodes, it all makes much more sense: C1 limits the current from the AC line
to the bridge rectifier formed by D1 to D4. The diode string, D5 to D8 (in
conjunction with D9) form a poor-man's zener to limit voltage across BT1 to
just over 2 V.
The Series 50 uses a sealed lead-acid battery that looks like a multi-cell
pack but probably is just a funny shaped single cell since its terminal voltage
is only 2 V.
Another model from First Alert, the Series 15 uses a very similar charging
circuit with a Gates Cyclon sealed lead-acid single cell battery, 2 V, 2.5
A-h, about the size of a normal Alkaline D-cell.
WARNING: Like many of these inexpensive rechargeable devices with built-in
charging circuitry, there is NO line isolation. Therefore, all current
carrying parts of the circuit must be insulated from the user - don't go
opening up the case while it is plugged in!
2V LB1 Light
1.2A +--+ Bulb S1
+--------|/\|----------o/ o----+
_ F1 R3 D3 | +--+ |
AC o----- _----/\/\---+----|>|--+---|----------------------+ |
Thermal 15 | D2 | | 4A-h | |
Fuse | +--|>|--+ | BT1 - |+ 2V | |
| | D4 +--------------||------|-------+
+----|<|--+ | | | |
| D1 | | D8 D7 D6 D5 | D9 |
+--------+-------+--|<|--+---+--|<|--|<|--|<|--|<|--+--|>|--+
| | |
| / |
_|_ C1 \ R1 |
--- 2.2uf / 100K |
| 250V \ |
| | R2 L1 LED |
AC o---+--------+--------------/\/\-----------|<|------------------+
39K 1W Charging
This uses a 3 cell (3.6 V) NiCd pack (about 1 A-h). The charging circuit is
about as simple as it gets!
S1
11.2 VRMS +---------------o/ o----+
AC o-----+ T1 R1 LED1 D1 | +| | | - |
)|| +----/\/\-----|>|---->>----|>|----+---||||||---+ |
)||( 33 Charging 1N4002 | | | | KPR139 |
)||( 2W BT1 | LB1 |
)||( 3.6V, 1 A-h | +--+ |
)|| +-------------------->>------------------------+----|/\|--+
AC o-----+ Light Bulb +--+
|<------- Charger ---------->|<---------- Flashlight ----------->|
I could not open the transformer without dynamite but I made measurements of
open circuit voltage and short circuit current to determine the value of R1.
I assume that R1 is actually at least in part the effective series resistance
of the transformer itself.
Similar circuits are found in all sorts of inexpensive rechargeable devices.
These have no brains so they trickle charge continuously. Aside from wasting
energy, this may not be good for the longevity of some types of batteries (but
that is another can of worms).
This is another flashlight that uses NiCd batteries. The charger is very
simple - a series capacitor to limit current followed by a bridge rectifier.
There is an added wrinkle which provides a blinking light option in addition
to the usual steady beam. This will also activate automatically should there
be a power failure while the unit is charging if the switch is in the 'blink'
position.
With S1 in the blink position, a simple transistor oscillator pulses the light
with the blink rate of about 1 Hz determined by C2 and R5. Current through R6
keeps the light off if the unit is plugged into a live outlet. (Q1 and Q2 are
equivalent to ECG159 and ECG123AP respectively.)
R1 D1 R3 LED1
AC o---/\/\----+----|>|-------+---+---/\/\--|>|--+ D1-D5: 1N4002
33 ~| D2 |+ | 150 |
1/2W +----|<|----+ | | R4 | D5
D3 | | +------/\/\----+--|>|--+
C1 +----|>|----|--+ | 33, 1/2W | LB1 2.4V
1.6uF ~| D4 | | | | | +--+ .5A
AC o--+---||---+----|<|----+--+---|--||||--------------+-+---|/\|----+
| 250V | |- | - | |+ | +--+ |
+--/\/\--+ | | BT1 + C2 - | R5 |
R2 | | 2.4V +---|(----|-----/\/\----+
330K | | | 22uF | 10K |
| | R6 | |/ E |
| +---/\/\---+-+-----| Q1 |
| 15K | |\ C +---------+
| / C327 | | |
| R7 \ PNP | | 1702N |
| 100K / | | NPN |/ C
| \ +---|-------| Q2
| On | | |\ E
| S1 o---------|-----------+ |
+----o->o Off | |
o---------+---------------------+
Blink/Power Fail
There are a simple movable mirror with incandescent or fluorescent lighting built in. Replacing incandescent light bulbs can usually be done without disassembly. The bulbs may be of the specialty variety and expensive, however. When a unit using fluorescent bulbs will no longer come on, the most likely cause is a bad bulb. However, replacement may involve disassembly to fain access. Where two bulbs are used, either one or both might be bad. Sometimes it will be obvious which is bad - one or both ends might be blackened. If this is not the case, replacement or substitution is the only sure test. These **will** be expensive $7-10 is not uncommon for an 8 inch fluorescent bulb! Other possible problems: plug, cord, switch, light bulb sockets.
A chandelier is simply an incandescent light fixture with multiple sockets. No matter how fancy and expensive, the wiring is usually very simple - all the sockets are connected in parallel to a cord which passes through the chain to a ceiling mounted electrical box. If none of the lights come on, check for a blown fuse or circuit breaker, bad wall switch or dimmer, a bad connection in the ceiling box or elsewhere in the house wiring, or a bad connection where the cord is joined to the individual socket wires. Where only one bulb does not light - and it is not a burned out bulb - a bad socket, loose wire connection at the socket, or bad connection at the point where the wires are joined (Wire Nuts(tm) or crimps) is likely.
These consist of a cordset, switch, and AC motor. Oscillating fans add a gearbox to automatically swivel the fan to direct air in more than one direction. Most are of the bladed variety though some small types might use a squirrel cage type centrifugal blower. There are two kinds of problems: totally dead or stuck/sluggish. A totally dead fan can be the result of several possible causes: * Bad cord or plug - these get abused. Test or substitute. * Bad power switch - bypass it and see if the fan starts working or test with a continuity checker or multimeter. Sometimes, just jiggling it will confirm this by causing the fan to go on and off. * Open thermal fuse in motor - overheating due to tight bearings or a motor problem may have blown this. Inspect around motor windings for buried thermal fuse and test with continuity checker or multimeter. Replacement are available. For testing, this can be bypassed with care to see if the motor comes alive. * Burned out motor - test across motor with a multimeter on the low ohms scale. The resistance should be a few Ohms. If over 1K, there is a break in the motor winding or an open thermal fuse. If there is no fuse or the fuse is good, then the motor may be bad. Carefully inspect for fine broken wires near the terminals as these can be repaired. Otherwise, a new motor will be needed. If the motor smells bad, no further investigation may be necessary! * Bad wiring - check for broken wires and bad connections. As always, your continuity checker or multimeter on the low ohms scale is your best friend and can be used to trace the wiring from the wall plug through all components of the appliance. Sluggish operation can be due to gummed up lubrication in the motor or any gears associated with an automatic oscillating mechanism. Disassemble, thoroughly clean, and then lubricate the motor bearings with electric motor oil. Use light grease for the gearbox but this is rarely a problem. A noisy fan may be due to dry motor or other bearings or loose hardware or sheetmetal. Disassemble, clean, and lubricate the motor or gearbox as above. Inspect for loose covers or other vibrating parts - tighten screws and/or wedge bits of wood or plastic into strategic locations to quiet them down. Damaged fan blades will result in excessive vibration and noise. These may be easily replaceable. They will be attached to the motor shaft with either a large plastic 'nut' or a setscrew. However, locating a suitable set of blades may be difficult as many cheap fans are not made by well known companies.
Virtually all of these use brushless DC motors with stationary coils and a rotating multipole magnet which is part of the blade assembly. Most common problems are gummed up lubrication or worn bearings - especially for the cheap sleeve bearing variety found in most PCs. Occasionally, an electronic failure will result in a dead spot or other problem. Ball bearing fans rarely fail for mechanical reasons but if the bearings become hard to turn or seize up, replacement will usually be needed. (Yes, I have disassembled ball bearings to clean and relube THEM but this used only as a last resort.) WARNING: For power supply fans, be aware that high voltages exist inside the power supply case for some time (perhaps hours) after the unit is unplugged. Take care around the BIG capacitors. If in doubt about your abilities, leave it to a professional or replace the entire power supply! The only type of repair that makes sense is cleaning and lubrication. Else, just replace the fan or power supply. It isn't worth troubleshooting electronic problems in a fan! If you want to try to clean and lubricate the bearings, the blade assembly needs to be removed from the shaft. There should be a little clip or split washer holding it on. This is located under a sticker or plastic plug on the center of the rotating blade hub. Once this fastener has been removed, the blades will slide off (don't lose the various tiny spacers and washers!) Thoroughly clean the shaft and inside the bushings and then add just a couple drops of light oil. Also, add a few drops of oil to any felt washers that may be present as an oil reservoir. Reassemble in reverse order making sure the tiny washers and spacer go back in the proper positions. How long this lasts is a crap shoot. It could be minutes or years. Replacement fans are readily available - even Radio Shack may have one that is suitable. Nearly all run on 12 VDC but some small CPU fans may use 5 VDC. While current ratings may vary, this is rarely an issue as the power supply has excess capacity. Air flow rates may also vary depending on model but are usually adequate for use in PCs.
The small fans used in computers and peripherals usually run on 5, 12 (most
common) or 24 VDC. Most of the time, their speed and air flow are fine for
the application. However, is it possible to vary it should the need arise?
Usually, the answer is a qualified 'yes'. Except for some that are internally
regulated or thermostatically controlled, the speed is affected by input
voltage. It is likely that the fan will run on anywhere from .5 to 1.25 times
the nominal input voltage though starting when it is near the low end of this
range may need some assistance.
A universal DC wall adapter, adjustable voltage regulator, or (variable)
series power resistor can provide this control. For example:
25, 2 W + +--------+ -
+12 VDC o-----+---/\/\---+--------| DC FAN |----o Gnd
| + | +--------+
+----|(----+ 12 VDC, .25 A
10,000 uF
25 V
The 25 ohms power resistor should reduce the speed of this fan by about 25 to
30 percent. The capacitor provides full voltage for a fraction of a second to
assure reliable starting.
The following comments should also apply to many other types of appliances using small AC motors. These small shaded pole fans will work just fine on a Variac. Any speed you want, no overheating, etc. I had done this with all sorts of little computer cooling fans as well as larger (remember those old DEC PDP-11 rack fans?). Small triac based speed controls like those used for ceiling fans may also work. Even light dimmers will *probably* work for medium size fans or banks of fans though I cannot guarantee the reliability or safety of these. The problem is that small induction motors represent a highly inductive loads for the light dimmer circuitry which is designed for a resistive load. I have achieved a full range of speeds but over only about 1/4 to 1/2 of the rotation of the control knob. There is some buzz or hum due to the chopped waveform. However, from my experiments, light dimmers may have problems driving a single small fan. If the load is too small, the result may be a peak in speed (but still way less than normal) at an intermediate position and the speed actually much lower when on full, or reduced speed even on full. In this case, adding a resistive load in parallel with the motor - a light bulb for example - may improve its range. It adds a sort of quaint look as well! :-) If you do opt for a solid state speed control, make sure you include a fuse in the circuit. A partial failure of the triac can put DC through the motor which would result in a melt-down, lots of smoke, or worse. The reason these simple approaches will work for these AC motors is that they are high slip to begin with and will therefore have a high range of speed vs. input voltage. The only concern is overheating at some range of lower speeds due to reduced air flow. However, since these fans are normally protected even against stall conditions, I wouldn't expect overheating to be a problem - but confirm this before putting such fans into continuous service. If all you need to do is provide a fixed, reduced speed for a bank of similar AC fans, try rewiring them as two sets of parallel connected fans in series. The result will be 1/2 the normal line voltage on each fan motor which may provide exactly the speed you want! The extension to more than 2 sets of fans is left as an exercise for the student :-).
While the original slow rotating ceiling mounted fan predates the widespread use of airconditioning, there is a lot to be said for the efficiency, effectiveness, and silence of this technology - not to mention the ambiance. A ceiling fan is just an induction motor driving a set of blades. Multiple taps on the motor windings in conjunction with a selector switch provides speed control for most inexpensive fans. Better units include a solid state motor speed control. The light often included with the fan unit is usually just an incandescent fixture with 1-5 bulbs and a switch. This may be a simple on-off type, a selector to turn on various combinations of bulbs, or a dimmer with continuous or discrete control of illumination. WARNING: Always check mechanical integrity of fan mounting when installing or servicing a ceiling fan. Original design and construction is not always as fail-safe as one might assume. Double check for loose nuts or other hardware, adequate number of threads holding fan to mounting, etc. These have fallen without warning. Only mount in ceiling boxes firmly anchored to joists - not just hanging from the ceiling drywall! Check that the fan is tight periodically. The constant vibration when running, slight as it is, can gradually loosen the mounting hardware. Furthermore, if pull chain type switches are used for the fan or light, constant tugging can also tend to loosen the entire fan. Failures of ceiling fans can be divided into electrical and mechanical: Electrical: * No power - Use a circuit tester to determine if power is reaching the fan. Check the fuse or circuit breaker, wall switch if any, and wire connections in ceiling box. * Bad switch in fan - with power off, check with a continuity tester. If wiring is obvious, bypass the switch and see if the fan comes alive. Jiggle the switch with power on to see if it is intermittent. For multispeed fans, exact replacements may be required. For single speed fans, switches should be readily available at hardware stores, home centers, or electrical supply houses. * Bad or reduced value motor start/run capacitor. This might result in slower than normal speed or lack of power, a fan that might only start if given some help, or one that will not run at all. For an existing installation that suddenly stopped working, a bad cap is a likely possibility. An induction motor that will not start but will run once started by hand usually indicates a loss of power to the starting (phase) winding which could be an open or reduced value capacitor. This is probably a capacitor-run type of motor where the capacitor provides additional torque while running as well. Therefore, even starting it by hand with the blades attached might not work. With the blades removed, it would probably continue to run. Of course, this isn't terribly useful! * Bad motor - if all speeds are dead, this would imply a bad connection or burned winding common to all speeds. There might be an open thermal fuse - examine in and around the motor windings. A charred smelly motor may not require further testing. A partially shorted motor may blow a fuse or trip a circuit breaker as well or result in a loud hum and no or slow operation as well. Mechanical: * Noise and/or vibration - check that fan blades are tight and that any balance weights have not fallen off. Check for worn or dry bearings. Check for sheetmetal parts that is loose or vibrating against other parts. Tighten screws and/or wedge bits of plastic or wood into strategic spots to quiet it down. However, this may be a symptom of an unbalanced fan, loose fan blade, or electrical problems as well. Check that no part of the rotating blade assembly is scraping due to a loose or dislodged mounting. * Sluggish operation - blades should turn perfectly freely with power off. If this is not the case, the bearings are gummed up or otherwise defective. Something may be loose and contacting the casing. (This would probably make a scraping noise as well, however).
(From: Chris Chubb (cchubb@ida.org)). I use synthetic transmission lube, 80-130 (manual gearbox, not automatic transmission fluid which is very thin --- sam). I imagine that any similar lubricant, synthetic or not, would work as well, but the synthetic flows down in better and works well. Do not use WD-40, 3-in-1 oil or any other lightweight oil. Motor oil is good as well, but it does not stick to the bearings as well. DO NOT use automatic transmission fluid - extremely thin. Grease would be perfect, white lithium, divine! But, getting the grease down into the bearings would be very difficult. Just about three or four drops should be all it takes. Getting it on the lower bearings of the ceiling fan will be tough. I have an oil can that I pump a drop to the tip of, then hold it against the bearings until they wick the oil inside. This is very slow. It takes about 15 minutes per fan to oil, clean the top of the blades, oil a little around the hanging ball, pull the globe off and clean the globe inside, and make sure everything is OK.
It is usually not possible to use a normal light dimmer to control the fan as this uses an AC induction motor. A dimmer can only be used on the built in light if a separate wire is available to power it. Doing this will likely result in a nasty hum or buzz at anything other than full brightness (speed) or off. This is both annoying and probably not good for the fan motor as well. A dimmer works by reducing the power to the light by controlling when the voltage is applied on each cycle of the AC. If it is turned on half way through the cycle half the power is provided, for example. However, with cheap lamp dimmers, this results in sharp edges on the waveform rather as peak voltage is applied suddenly rather than with the nice smooth sinusoid. It is these sharp edges causing the coils or other parts of the fan to vibrate at 120 Hz that you are hearing. Special speed controls designed for ceiling fans are available - check your local home center or ceiling fan supplier. Here is another alternative: (From: Rick & Andrea Lang (rglang@radix.net)). Here's a potential solution if you don't mind spending a little more for a ceiling fan (If you already have one in that location, perhaps you can put it in another room). Ceiling fans with remote control are now available. They only require power to the ceiling fan (2 wire) and a remote control. With the remote you can dim the lights, slow the fan or both. You can then use the existing new wall switch as a power ON/OFF switch also. If you choose this route, be careful of interference with garage door openers. Usually, the remotes have at least 4 frequency selections to help avoid interference with other remote systems. I put one in that three of the four frequencies opened the garage door. I lucked out on the 4th one!Go to [Next] segment
Go to [Table 'O Contents]