Showing posts with label basic. Show all posts
Showing posts with label basic. Show all posts
Two Basic Motor Speed Controllers
Here are two simple 12V DC motor speed controllers that can be built for just a few dollars. They exploit the fact that the rotational speed of a DC motor is directly proportional to the mean value of its supply voltage. The first circuit shows how variable voltage speed control can be obtained via a potentiometer (VR1) and compound emitter follower (Q1 & Q2). With this arrangement, the motor’s DC voltage can be varied from 0V to about 12V. This type of circuit gives good speed control and self-regulation at medium to high speeds but very poor low-speed control and slow starts. The second circuit uses a switchmode technique to vary motor speed.
Here a quad NOR gate (IC1) acts as a 50Hz astable multivibrator that generates a rectangular output. The mark-space ratio of the rectangular waveform is fully variable from 20:1 to 1:20 via potentiometer VR1. The output from the multivibrator drives the base of Q1, which in turn drives Q2 and the motor. The motor’s mean supply voltage (integrated over a 50Hz period) is thus fully variable with VR1 but is applied in the form of high-energy "pulses" with peak values of about 12V.
This type of circuit gives excellent full-range speed control and gives high motor torque, even at very low speeds. Its degree of speed self-regulation is proportional to the mean value of the applied voltage. Note that for most applications, the power transistor (Q2) in both circuits will need to be mounted on an appropriate heatsink.
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Fig.1: a very simple motor speed controller based on a compound emitter follower (Q1 & Q2).
Here a quad NOR gate (IC1) acts as a 50Hz astable multivibrator that generates a rectangular output. The mark-space ratio of the rectangular waveform is fully variable from 20:1 to 1:20 via potentiometer VR1. The output from the multivibrator drives the base of Q1, which in turn drives Q2 and the motor. The motor’s mean supply voltage (integrated over a 50Hz period) is thus fully variable with VR1 but is applied in the form of high-energy "pulses" with peak values of about 12V.
Fig.2: this slightly more complicated circuit gives better low speed control and higher torque.
This type of circuit gives excellent full-range speed control and gives high motor torque, even at very low speeds. Its degree of speed self-regulation is proportional to the mean value of the applied voltage. Note that for most applications, the power transistor (Q2) in both circuits will need to be mounted on an appropriate heatsink.
BASIC ELECTRICAL CIRCUITS
This subcourse is designed to give you a basic knowledge of simple circuits that carry electricity from a power source to some kind of electrical equipment. With a knowledge of these fundamentals, you will be able to make better use of electrical equipment and to better understand future textual materials that mention electrical factors in the function of equipment.After completing the programmed text, you should be able to choose correct answers to questions about basic electrical circuits, current, resistance, amperes, volts, and equivalent.The series circuit below is an equivalent circuit because both circuits (do/do not) have the same E a and both circuits. Now that you know what happens to resistance and voltage in a parallel circuit, let us look at current.
Basic Components for a Home Theater
Many people never bother looking into purchasing a home theater through sheer fear of the decisions that may need to be made in the process. Many among these aren’t even sure of exactly which components are included in a home theater or which ones are needed in order to create an effective and entertaining home theater. For this reason, many people simply do not bother going through the process of looking at their options when it comes to these wonderful systems on the market today much less ever bother actually purchasing one.
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| Basic Components for a Home Theater |
If you are one of the many who has experienced some degree of confusion when it comes to the individual parts and pieces that are included in a home theater system and what they do, hopefully you will gain a better understanding once you’ve finished reading. The first thing to understand is that there are varying degrees when it comes to home theaters. The following components are the makings of a very basic home theater that will provide excellent functionality. They are not however inclusive of every possible piece or part that could make up a home theater system.
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| Speaker Setup |
Off to the basics, the first thing you’ll need when creating a home theater for your family to enjoy is a television. It might seem a little too obvious to some but I have yet to find a box kit that includes a television—mainly because the choice of screen is for many the most personal aspect of selecting a home theater. There are essentially three choices in today’s television market: front projector, rear projector, and plasma. There are variations within each of these and the prices fall anywhere from modest to quite costly. This is the component that most home theater owners spend the most time contemplating and it affects the types of components that will be most effective later on in terms of things such as high definition and other choices you can make.
A receiver is another important component. You will probably have a DVD player or recorder of some sort as part of your system; you may have a Tivo and cable box or satellite and will probably have speakers of some sort for your system. The receiver is the box you plug them all into—it receives all of this inputs and correlates it so to speak. This is the ultimate traffic director when it comes to your home theater and I suggest you spend a good portion of your home theater budget making sure that this is a good quality part.
Speakers are where your sound will flow. One of the best things to me about a home theater is the ability to experience surround sound very similar to what I experience in theaters while having the ability to put my feet up or snuggle under blankets (which simply can’t be achieved in a theater). Speakers come in all shapes and sizes and are also quite personal for some consumers while give and take for others. You can purchase these are part of a kit in order to make the selection process easier.
Finally, you have your DVD player or recorder. If high definition is important to you, you now have that option. If your television isn’t HD ready or capable, I’d pass and go for an older (less expensive) model of DVD player until something more up-to-date is called for. These items are a great start for any home theater and you can build, expand, and upgrade over time for an even better system. Enjoy!
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Related Circuit : Make 5.1 channel amplifier and speaker setup
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