AUTO TURN OFF BATTERY CHARGER

         This charger for series-connected 4-cell AA batteries automatically disconnects from mains to stop charging when the batteries are fully charged. It can be used to charge partially discharged cells as well. The circuit is simple and can be divided into AC-to-DC converter, relay driver and charging sections.

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        In the AC-to-DC converter section, transformer X1 steps down mains 230V AC to 9V AC at 750 mA, which is rectified by a full-wave rectifier comprising diodes D1 through D4 and filtered by capacitor C1. Regulator IC LM317 (IC1) provides the required 12V DC charging voltage. When you press switch S1 momentarily, the charger starts operating and the power-on LED1 glows to indicate that the charger is ‘on.’

       The relay driver section uses pnp transistors T1, T2 and T3 (each BC558) to energise electromagnetic relay RL1. Relay RL1 is connected to the collector of transistor T1. Transistor T1 is driven by pnp transistor T2, which, in turn, is driven by pnp transistor T3. Resistor R4 (10-ohm, 0.5W) is connected between the emitter and base of transistor T3.

        When a current of over 65 mA flows through the 12V line, it causes a voltage drop of about 650 mV across resistor R4 to drive transistor T3 and cut off transistor T2. This, in turn, turns transistor T1 ‘on’ to energise relay RL1. Now even if the pushbutton is released, mains is still available to the primary of the transformer through its normally open (N/O) contacts.

          In the charging section, regulator IC1 is biased to give about 7.35V. Preset VR1 is used for adjusting the bias voltage. Diode D6 connected between the output of IC1 and battery limits the output voltage to about 6.7V, Pushing switch S1 latches relay RL1 and the battery cells start charging. As the voltage per cell increases beyond 1.3V, the voltage drop across resistor R4 starts decreasing. When it falls below 650 mV, transistor T3 cuts off to drive transistor T2 and, in turn, cuts off transistor T3. As a result, relay RL1 de-energises to cut off the charger and red LED1 turns off.

         You may determine the charging voltage depending on the NiCd cell specifications by the manufacturer. Here, we’ve set the charging voltage at 7.35V for four 1.5V cells. Nowadays, 700mAH cells are available in the market, which can be charged at 70 mA for 10 hours. The open-circuit voltage is about 1.3V.

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With Auto Sound Systems Newest Technology isnt Necessarily Greatest Technology

We live in a world where music is our constant companion. We take it with us to the beach, to work, to exercise, even while riding bikes or talking on our cell phones. It only makes sense that in our cars we would like to have the best possible auto sound systems our hard earned dollars can buy. The problem is that new technology is being introduced to the market each and every day and many of us feel as though if we hold our breath just a little bit longer something even better and more spectacular will come along. We know that we will absolutely want to kick ourselves if we buy in to "this or that" companys auto sound system that was phenomenal yesterday, just before the next great thing hits the market.

The truth is that superior auto sound system technology exists already and the question isnt if it will hit the market but rather when. And when seems to be a pretty big question when it comes to emerging technologies. There are always so many things that control when the actual product will hit the shelves in stores or even how much supply will be available at that point in time. The really good news for consumers is that if you wait until that point, chances are the prices on the system you like now will probably lower significantly almost overnight.

While the geek in me would love to have the latest and greatest of gadgets at all times, the mom in me knows that the kids will need braces, new shoes for soccer, and (eventually) college tuition. For those reasons, I will continue typing on my sadly outdated eMachine and secretly long for the brand new Dell notebook while listening to the latest tunes on my iPod Shuffle while secretly longing for one of the new iPods, which is capable of playing video. I will live however, and will enjoy watching others play with their new gadget goodies while I learn about them and wait for the prices to drop (just like DVD players a few years back).

I am at least intelligent enough to realize that most of the time it is best not to be the first to buy a new product or an emerging technology. Let someone else take the risks associated with buying an essentially untried product while I sit back and listen to what they have to say. This way I can make an informed decision without bearing the scars associated with testing an untried product.

There are many things Im willing to sacrifice and many more things I give to my children as guinea pigs. The thing I have noticed quite often with them is that if it can survive a few weeks in their care, it is a pretty safe bet and might even be worth purchasing stock in the company. We all have some things that are more important to us than others and while I love technology there are other things I love more.

Music, however, is a very important part of my life and I do try to keep current with the latest and greatest when it comes to auto sound systems. My favorite at the moment is the Bose. Every piece of this equipment is designed with the idea of making music sound, as it should. You can get the biggest and greatest sound quality from this system without giving up half your trunk or your entire back seat. Bose is one of the more expensive products on the market when it comes to auto sound systems but it is well worth every penny.

When checking out your options for an auto sound system be sure to keep in mind that the most expensive product is not necessarily the best product-no matter what the salesman tells you. By learning as much as possible about all choices you may find that one of the less expensive systems is actually better suited for your auto sound system needs.

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Technology Spending Limits and the Auto Sound System

We live in a world that is constantly changing and evolving. We see it every time we buy a new car, a new television, or a new computer. We see it every other month when the iPod is putting out a new an improved model that offers more features, more disk space, and more everything, in a smaller package (well not since they added video but until then, the gadgets were getting smaller while the features were growing exponentially). The truth of the matter is that technology seems to be advancing at a rate that is nearly impossible to keep up with. That being said, you can quite literally drive yourself insane by trying to keep up with the pace of modern technology.

What you need to do in order to maintain proper sanity is decide on a level of technology that you are comfortable and confident with and go with it until it is time (by either necessity or desire) to upgrade. You do not have to be the first to purchase the latest and greatest in software and gadgetry (this has become my mantra: I do not have to be the first to own the great big bad new toy, I will survive gadget deprivation-it isnt working yet but Im ever the optimist). The point is that you do not need to be the first to try every new thing and you will not only wear yourself out by trying but also you bank account, credit cards, and second mortgage. Technology is expensive, especially the newest and latest. If there was any doubt stroll on over to Ebay and see how much Play Station 3s are selling for at the moment-madness and lunacy do not even begin to subscribe the amount of money people are offering to pay for these devices.

Technology is a wonderful thing. It makes life easier for some and a lot more entertaining for others. The same holds true with auto sound systems. The technology exists to make them much more beneficial to car and driver than they have been in the past while offering many more features than ever before. Today you arent even limited to AM and FM. You now have the option of CDs, audio books, MP3s, XML, and digital FM radio, which offers a few bonus features over traditional radio. It really doesnt matter if you have the absolute latest. Most of us can enjoy a great deal of the wonderful technology that is available if we are willing to wait long enough for the prices to go down. I recall, and it wasnt all that long ago, when DVD players sold for no less than $100. You can get them now (about 5 years later) on a regular basis for less than $30. This is only one example of many. PS2s were around $400 when they first hit the market and now can be bought at the whopping price of $120. All around us technology evolves and grows and then prices fall.

The point is spend your money where you want to spend it rather than where you think it should be spent. If you want an auto sound system then get the best one that you feel meets your budget requirements. You do not have to have the top system in the technology food chain in order to have a great sound system that will provide you with years worth of enjoyment. You are the only one that is responsible for the decisions you make. It is up to you to decide where you want the bulk of your money invested when it comes to technological gadgets and goodies. Believe me, Im a gadget geek. I love playing with new toys and gizmos and seeing how they work-really, for me its a thrill. At the same time I realize I cant always be the first to get the new toys I so desperately want to try out so I limit myself and decide which ones are the most important. You must do this for yourself when it comes to auto sound systems.

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Auto Sound Systems One Piece at a Time

Those who are in the market for auto sound systems are probably well aware of the many decisions that need to be made throughout the process. Gone are the days when you went in, pointed to a box and walked out with all the pieces, parts, and components you would ever need for a really kickin sound. The truth of the matter is that there are many pieces and parts that work together in order to create the ultimate sound system and everyone seems to have different requirements, styles, tastes, and budgets to work with.

Because of this, many manufacturers of auto sound systems have wised up to the fact that some people will buy the components they need to create the sound system of their dreams piece by piece as budgets allow. This is actually a very intelligent way for customers on a budget to buy the sound system they are hoping to some day have. As a result you will find that speakers, amplifiers, sub woofers, and the actual stereo are often sold separately and at very reasonable prices.

Most of us hate living within limited budgets but understand that often in life it is a necessary evil. Living on a budget is not such a terrible thing really. If we had everything we wanted, what on earth would there be to look forward to? At least that is what I keep telling myself. I, however, seem to be the queen of budget living and bargain hunting. I love little more in life than finding a great deal on an item Ive had my eye on for quite a while and hate little more than finding it cheaper once Ive purchased it. As such, I tend to invest a great deal of time researching any major purchase before taking the plunge. A good auto sound system by this I mean good quality, minimal features is going to run (total package and installation) at least $1,000 with many costing a good deal more than that.

That doesnt mean you need to have a thousand bucks lying around the house in order to begin building your auto sound system. You can buy a decent set of speakers for around $200-$260 if you desire. You can find sets at lower prices, but this is the price for a fairly decent set of speakers that should serve you well. Keep in mind that you could very easily spend a lot more than this on speakers if you arent careful. Living on a budget means you have to make some sacrifices along the way in order to have the things you want in life. Buy the speakers and have them installed (if you can do it or your know someone who can, this will save a lot of time and money).

Once you have the first component, whichever one that may be (that choice is entirely up to you and largely dependent on your personal tastes and which need replacing worse in the vehicle you own) you can begin saving towards the next. You should also consider asking friends and family (who would like to know what to get you for the holidays) to help you reach your smaller goals along the way. Most people are glad to help with specific items if they know what those items are. The point is that this isnt an all or nothing proposition. Take small steps towards your prize and you will find that you are constantly getting one step closer.

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