GBC Tech Video News

Ferrite beads and chokes both have impedance characteristics that can be employed as filters and safeguards to muffle unwanted interference in electronic circuits. Random high frequency signals, also know as “noise”, can cause other nearby circuits to fail to operate correctly.

An analogy for unwanted noise on top of the signal is being at a party and trying to have an intimate conversation with someone you can’t hear because everyone else around you is being too loud. In circuits, through electromagnetic coupling, a circuit that has extremely sharp pulses can induce extra signals over and above the main signal in a nearby circuit and thus becomes a source of noise, which makes it almost impossible for the receiving circuit to interpret the main signal.

So, what exactly are these things? A ferrite bead or choke is a non-resistant electronic member composed of ferromagnetic compounds that contain iron and trace amounts of nickel, zinc, or manganese oxides. The impedance properties of the ferrite choke allow it to act with a high resistance to high frequency signals and low resistance to lower frequency signals. This way, the high frequency noise is damped out and the absorbed energy is converted to a very small amount of heat. The type of ferrite material used in the bead will determine the range of frequency suppression, and the physical dimensions and shape of the ferrite bead determine the amount of suppression possible.

The beads themselves can be nothing more than a dowel-type device that has a hole in the center or something that looks like a metal blob, which is really a multi-layer bead utilized in surface mount applications. Electromagnetic Interference (EMI) suppression beads, which are comparable to inductors, are designed to rise in the transmission of signals with frequency until a resonance point. While a regular inductor’s wave propagation would begin to drop as frequency continued to increase, the ferrite bead inductance flattens out and acts as a perfect muffler for a wide frequency band.

One extremely basic use of ferrite chokes is on computer cables. You’ve probably seen these before; they look like a bump or a cylinder in the cable. These cylinders are snap-on ferrite beads that suppress the potential RF interference from the cables.

They can also be used in cell phones. There is no agreement on whether the radiation that emanates from cell phones will result in damage to one’s brain, and there are various devices being offered for sale like ferrite chokes or shields that are crafted with the intention of suppressing the radiation and the interference from the phone. If your cell phone is located anywhere near the speakers of your PC, you will actually hear this interaction of sound waves or interference.

Usually what happens is that you hear an irritating buzzing, which occurs because the cables on those speakers pick up the energy transmitted from your cell phone. Besides adding beads to your own telephone, you might also want to put snap-on-beads on your speakers to muffle the interference (unless you want the two second alarm that your phone is about to ring).

Because today’s circuits are faster and more of them are packed onto a circuit board, it is extremely desirable to employ ferrite beads and other techniques to suppress noise. Digital designers only think in terms of ones and zeros signaling until they uncover the nightmare of the sphere of analog where there is noisy circuit conduct or interference from power supplies or problems with grounding.

Besides protecting yourself from your own circuits, there are numerous “harden applications” where you need to protect the circuits and muffle any noise caused by external sources. An example would be a strong transmitter such as a cell phone accidentally being operated on a plane or a more purposeful attempt to jam a military application.

Ferrite bead and chokes are basic devices that can serve as the first line of defense for RF muffling and other noise suppressing uses. A company that produces beads can give you the arcs of impedance vs. the frequency for the beads they manufacture; typically their application engineers can assist you in choosing the correct type of bead.

Discount portable dvd players – Watch movies anytime and anywhere you want with Sony’s cool and colorful DVP-FX820 Portable DVD Player. It features an 8″ high-resolution swivel display that provides a clear and crisp picture from any angle, two headphone jacks for sharing, and a vehicle adapter that guarantees your movies survive even the longest travel. The FX820 runs your CDs or MP3s and permits you to see your memorable photo albums when you require more than movies. Sit back and relish the crispy and sharp picture with this Sony hi-res LCD screen.

Customer Reviews

I admit to not being very sharp when it gets to tech stuff. But I just got so crazy and tired of the fuss in hooking one-thing-up-to-another-thing to just sit by, unwind and enjoy. Now I can make all that with ease anywhere and enjoy my favorite motion pictures and educational shows with the most superb picture quality possible along with its fantastic portable ease-of-use and truly long-life battery time. Moreover, even though it was a bit more than I needed to expend at the outset, I enjoyed that my wallet got that extra mile because this is a truly solid investiture that will grant nice viewing, listening and learning – like the song says…as time passes by. – Katherine Graham

I purchased this DVD player in expectation for a flight to Vegas from Orlando and then back. I got on the plane with a full battery and when we arrived in Vegas, there were still 2/3 bars. The battery life was fantastic and the picture quality was splendid. When you’re watching a film, you’ll be fascinated by it. Praise on this one. I like it!! – N. Ledet

I have owned the original Sony DVP-FX810 and that was an adept player too. I sold that and purchased this one. The resolution is almost twice as high as the original. Simply purchased this but I can tell you the display really shines compared to every other DVD player (portable) that I’ve come across. I’m sure more players will have the high resolution soon. The audio system is also much louder than the original.

The battery is supposed to last 6 hours at lowest brightness. With my previous one which is basically this I did pull off 5 hours at medium brightness so 2 movies should operate all right before the low battery symbol shows. I needed the red dvd player but the Sony Style at Metreon had everybody except the red but the blue is good too. Highly recommended. – Mark

Small and portable. Splendid display. Functioning long and clear. This is the 3rd portable DVD player I owned and we truly like it. Bought for extended use on an airplane ride. Not concerned about volume, I can hear it just all right under normal circumstances. – BigPoppy

I’d unquestionably highly recommend this portable player for general and air-travel use entertainment. The picture is superb and the audio and controls are effectively positioned. – Mark V. Novas

While storing data in your MP3 player, you seldom stop to find how files are saved in the player’s memory. The different types of memory types include internal flash memory, Compact Flash cards, Smart Media cards, Memory Stick and internal micro drive.

Except for internal micro drive, all of the above mentioned are ‘solid-state’ memory types in which there are no moving parts. This enables better reliability and no skips while you are enjoying the music. There are tiny hard disk drives in MP3 players which have capacity to store 10 to 150 times more date compared to flash memory devices.

In any MP3 player, the microprocessor is the brains of the system, monitoring user input through playback controls, displaying all the statistics related to the song playing on the LCD panel and sending instructions to the DSP chip that tells exactly how to process the audio.

The DSP withdraws the data of songs from memory, through application of special effects, or EQ, and streams it to the amplifier. A decompression algorithm run by the DSP will undo the compression of the MP3 file and then a digital-to-analog converter will change the bytes back into sound waves.

After boosting the strength, the amplifier sends the signal to the audio port, which is connected to a pair of headphones.

MP3 players are portable and battery-powered. Most of them use one or two AA batteries that last for about 10 to 12 hours on a single charge. Many players are equipped with AC adapters and can be plugged into a normal electrical outlet and some even offer DC adapters for use in a car.

Minidisk technology comes to music listeners in a new and improved line of Minidisk Walkman digital music players. A 1 GB disc is provided by Hi-MD technology to give users up to 45 hours of music. Those looking for a player that can store their entire music collection would find the hard drive ideally suited for the purpose. These discs can also store and transfer many PC data files to enable PowerPoint presentations, spreadsheets, etc. and depending on the model, it could allow 30 to 50 hours of playtime on a single AA battery.