***"Mowie, while you have written an impressive book, some of which actually applies to the question at hand, I question that portion."*** OK, It is "an alternator" by the modern definition of alternator. That means the alternating current (which is caused by the alternating North & South poles passing the coil) is presented to a diode to be rectified electronically by a semi-conductor, instead of being rectified physically/mechanically by a rotating commutator. And keep in mind, I am talking about an alternator that uses permanent magnets to create the rotating field. Also, keep in mind that these alternators actually swap the roles of the same compontents (rotating member= rotor, stationary member= stator). In a "DC generator", the current created is AC, but the useful OUTPUT power produced in the rotor (aka armature), is rectified by the commutator at the same time it is delivered to the machine's electrical system via a set of brushes that contact the commutator. The field is stationary in a DC generator, and varying the voltage fed to the field, will vary the voltage output of armature. Because the commutator is a physical and mechanical, "rotating contactor", the polarity of the current being created in each individual coil of the armature (and their are several) must be absoutely identical to the polarity being created in the other coils, otherwise, you would be feeding a pulse of "opposite polarity" into the battery whenever that coil's commutator bars came into contact with the brushes. This opposite polarity pulse would have the effect of "discharging" the battery each time it offered its current to the mix. But I don't know of ANY DC generators ever employing "permanent magnets" as the sole exciting source of field current. Yes, all the DC generators did/do have and use, residual magnetism in the field shoes as a result of the electromagnetic processes that take place during operation. But, that residual magnetism came to be used as a means of ensuring that the generator could begin making electricity by itself (with no external current applied to the field), even if the machine's battery was "stone dead". But, if there was an application that used PERMANENT MAGNETS as the "sole" exciting field for a DC generator, ALL magnets in the field would have to be arranged in identical polarity or the output would have some pulses of opposite polarity, which would have the same effect on a battery as if you fed alternating current to the battery, and a battery can not utilize AC because a battery is strictly a DC based component. AC fed to a battery results in a "null charge condition" because for every pulse of current in the correct direction that could add a bit of charge to the battery, there is also a pulse of current in the wrong direction that subtracts a bit of charge from the battery. OK, let's jump to an alternator that uses several permanent magnets in a rotating field (flywheel in this case) and several coils of wire in a stationary output component. This hypthetical example alternator is a "single phase" version (meaning it has only one output conductor offering power to be rectified). Keep in mind here that electricity travels at about the same speed as light (commonly referred to as 186,000 miles per SECOND), while the flywheel turning 3,000 RPM, is hardly even creeping in comparison. As each permanent magnet in the flywheel rotates past one of the coils in the stator, a current is induced in the coil. Because the magnet has a North pole & a South pole, the induced current will change its direction of flow, from "North to South", or, from "South to North", depending on the physical orientation of magnet's North & South poles as it passes the coil. The output current of each coil tries to travel out of the coil, through the other coils (they are all in series on this circuit), and into the electrical system of the machine, THROUGH THE BATTERY, and out to ground where this pulse will re-enter the coil wiring at the other end of the coil (stator wiring has 2 ends, one end is "output", the other end is connected to the engine and chassis ground, if you do not provide a complete path, you get no flow of current). OK, it does not matter which direction the induced current is flowing through the coil when the induction begins (magnet is approching the coil), nor which way the induced current is flowing when the induction ends (magnet is departing the coil) because the rectfying diode is only going to allow the half of the total power pulse that has the correct polarity, to pass through and travel the complete circuit through the battery and finally back the stator through "the back door". When multiple magnets are used with a single circuit stator, either the magnets, or the individual coils must be "staggered" or, unevenly spaced along the circular layout alternator to prevent any "butting of heads" of power pulses that might be caused by two magnets having opposite polarity. And because all of the electrical induction and power output pulses occur at light speed, an individual coil waiting for the next passing magnet, could be likened to someone waiting at a bus stop, for a bus that only comes by twice a day. So, it does not matter about the polarity of each magnet in this application, the diode decides which half of each pulse it will permit to go to the battery, whether that correct half shows up at the gate first......or last.

Bob you should check it out. The plants in the conservatories are just gorgeous and the butterflies and hummingbirds flying around are really something. The outside gardens are beautiful as well and you can get some cool plants. It's really close to you. I'm surprised that you've never been. I'll be going again. I never get tired of it. I have no idea if we'll be flying or driving. Even with cheap fares it's expensive to fly 5 people anywhere but with the price of gas........ Karyn

Sorry about the late response. I bought a "Mosquito Magnet" Defender model last summer for my residence. Here's the GOOD NEWS: on my lawn, the colorful, sophisticated, quietly-purring Mosquito Magnet (MM) served as a terrific conversation piece for passers-by. Postal letter carriers, package and daily newspaper deliverers, campaign candidates, neighbors, walkers, joggers, ect. were universally fascinated by the gadget. It resembled, at once, something very exotic -- such as a mechanical pet robot or an Andy Warhol-like, artistically-painted, lawn ornament. Consequently, I became much more acquainted with my neighbors and other unknowns who stopped to inquire about the strange contraption. The NOT-SO-GOOD NEWS is that the costly MM confirmed my worst fears: It totally under-performed. After 6 weeks of ownership the MM had trapped fewer than 100 mosquitoes. Unlike some owners complaints, my MM always started and operated as advertised. The problem arose from the reality that it didn't catch many insects. Throughout the summer, I experimented with relocating the MM around my yard and chemical attractants -- with similar disappointments. Frustrated, I plucked the device into the most infested area of the property, reasoning that it had to at least trap blood-suckers -- even if it didn't significantly reduce the general population. Result???: A few hapless mosquitoes wandered to their deaths, but certainly no more than I could have swatted myself in about 10 minutes. I carefully maintain the MM according to the manual, used attractants, and regularly consulted with MM service reps -- all to little avail. Ironically, insects appeared somewhat interested in the MM, as I observed flies, mites, and mosquitoes hoovering around and crawling over the appliance. I suspect, like my neighbors and others, they were fascinated by the machine, too!!! Also, the MM is not inexpensive to operate. It requires electricity 24/7 along with refills of propane, chemical attractants, and C02 cartridges every 21 days. Meanwhile, I now totally understand why the nursery sales person where I bought the MM was evasive when asked about the nursery's return policy on the MM. She coyly explained that the nursery had sold literally dozens of MMs with no returns! When pressed, however, she conceded that the manufacturer (American Biophysics Corporation) no longer accepted returns from dealers and required individual customers to directly contact ABC. That should have been my second clue: My first being the "Love 'Em," "Hate 'Em" electronic bulletin board divisions about the MM! I think the MM is a great idea, but the science and technology isn't quite there to support it -- yet. To date, scientists and manufacturers simply don't know enough about mosquito behavior to design, mass produce, market, and sell safe, reliable, affordable, and ecologically-friendly mosquito exterminators. Now, can anyone tell me how to avoid the embarrassing snickers from my neighbors for buying such an expensive, well, uh,...lawn ornament??? Really Blue Ace

Wow, thanks Kimberly for reviving this old thread. Because I have learned some things in the meantime. (Automotive HID lights tend to be more expensive, compared to what's available elsewhere). I repeat my warning to not use the Philips retro-hps bulbs (the CDM400S51/HOR/4K/ALTO; the GE equivalent is CMH400/U/830/R) on the GE Ultra-max e-ballast. Also do not use these on any high or very high frequency e-ballast. There is a CMH bulb designed for use with low-frequency e-ballasts like the GE Ultra-max; the SPXX. However at present is available only in vertical orientation (horizontal is recommended for various reasons). Ceramic arc tubes (like those in HPS and retro-hps CMH) were designed for use with magnetic ballasts and have a stable arc stream in that case. However if subjected to high frequency electronic ballasts the arc stream is unstable and this heat-stresses the bulb. This explains Shrubs' comment that electronic ballasts run the bulbs hotter. This is not just because some (like Lumatec) slightly over-wattage at 1050w. The instability in the arc stream heat-stresses the ceramic elements, causing premature failure and leakage of heavy metals including mercury. Eye Hortilux is the premier manufacturer of conventional horticultural lighting. They published an article in the October issue of Maximum Yield magazine. They point out, HPS and MH bulbs are not suited to high-frequency e-ballasts (with frequencies between 30,000 and 45,000 cycle per second). Which explains the high failure rate and increasing number of lawsuits. For the article, go to maximumyield.com and click unto "Download MY". Then scroll down to the third section of October 2008. Notice, old-style MH are also not compatible with e-ballasts. Even though they are not using the glued ceramic arc tube, the quartz can still rupture and in any event the instability creates a heat stress (shortening bulb life). Sun-Pulse bulbs are designed to have stable arc stream with e-ballasts tuned to them. Sun-Pulse are the only PSMH bulbs designed specifically for e-ballasts. Lumatec, Galaxy, and GE are the only e-ballasts that have been tuned to the Sun-Pulse bulb. There is an electronic e-ballast that is very high frequency (about 300,000 cps) but they go only to 600w and are not readily or cheaply available. As I pointed out in previous posts, this very high frequency is desirable for plant growth because it is closer to natural sunlight. However CMH requires a specific type of low frequency e-ballast (or magnetic ballast). Not all low frequency e-ballasts are compatible with all CMH. PSMH can use either low or high or very high frequency. Because CMH uses ceramic arc tube (which is glued together) it is inherently unstable at high frequency or high wattage. Sun-Pulse are a type of PSMH that are designed specifically for e-ballasts. I recommend the Sun Pulse bulbs over CMH, however they cost more. So for those who cannot afford, use magnetic ballast with CMH. Use the 10K Sun-Pulse for veg, the 3K or 4K for bloom. The Sun-Pulse are even more full-spectrum than CMH. A 400w Sun-Pulse (or cmh) produces far more intensity than can realistically be achieved with fluorescents. The high intensity should be moved quickly in a circle, to cool the bulbs and distribute the light evenly. If this is not feasible (for lack of space or money), combine several 400w bulbs in a cluster and overlap their fringe areas. This simulates how the points in linear fluorescents overlap fringe areas (a 4' line fluorescent tube has an infinite number of points and increasing the number of tubes creates overlapping in more directions).