B2B Electronics

In electronics, polarity determines how a component should be inserted into a circuit. A non-polarized component can be connected in any direction and will still function properly. A polarized component can only be inserted in one direction. Unlike incandescent light bulbs, which illuminate regardless of the electrical polarity, LEDs will only light with correct electrical polarity. When it comes to through-hole LED’s a polarized component usually has two pins.

If a polarized component is inserted incorrectly it may not work at all, or it may smoke, spark or fail. It’s a little bit harder to determine the polarity with Surface Mount LEDs (SMT LEDs). Surface mounted device LEDs (SMD LEDs) are electronics components without the connecting wires used with through-hole devices. Although initially intended for automatic manufacturing their use has expanded into hobby electronics. Smaller components lead to more compact circuitry and smaller devices. In fact, some components are available in SMD versions only.

Continuity Tests using a Multimeter

Often the easiest way to determine polarity of an SMT LED is by using a simple multimeter. This is achieved by carrying out a simple test: we set the selector to ‘Diode’ or ‘Continuity Test’ mode and place a probe on each end of the LED. Usually, the multimeter will supply enough current into the LED which will just barely light it up. However, there’s no guarantee your meter won’t over-do the current, so we recommend doing just a quick touch, or putting a resistor in line. The black (common) lead on the multimeter indicates the negative (cathode) lead, and the red indicates the positive or anode side. It will only emit light when the negative probe is on the cathode end and the positive probe is on the anode end. When the voltage across the p-n junction of the LED is in the correct direction, a significant current flows and the device is said to be forward-biased. If the voltage is of the wrong polarity, the device is said to be reversed biased, very little current flows, and no light is emitted. Of course, the best method to determine the polarity of your LED, the pinout, along with all the other specs is to locate the manufacturer’s datasheet.

Visual Inspection

The majority of LEDs have the cathode end marked, however it has been noticed that even within the same range of LEDs from the same manufacturer, there are differences. Red LEDs seem to be the exception, having a mark on the anode end, not the cathode one. Most often if you cannot see any of these markings, a small notch or dot will indicate the negative side of an LED. SMT LEDs typically have a dot or small green line indicating their cathode. Lighthouse LEDs provide a selection of SMD images in their Polarity Guide for 0402, 0603, 0805, 1206 and most all SMD LEDs.

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Article Source: http://www.limetrace.co.uk/how-to-determine-the-polarity-of-an-smd-led

The advancement in technology has enabled us to use a variety of gadgets, such as smartphones. Since these gadgets communicate wirelessly, the use of wireless antennas is on the rise. Whether at home or office, people find it more convenient to use devices that use WiFi antenna to communicate with each other.

WiFi antennas are better than traditional dipole antennas in more ways than one. The thing is that wireless antennas are capable of sending and receiving RF signals. Moreover, wireless networks work when radio transmission is sent through specific frequencies. Listening devices receive the transmitted signals. Some good examples of wireless devices are smartphones, laptops, and routers. These devices feature built-in radio signal receivers and senders. The antennas receive incoming RF signals radiating outgoing signals simultaneously.

Antennas found in routers can be mounted externally. However, other types of antennas are installed within the electronic devices. If you want to buy a WiFi antenna, you may want to keep a few things in mind.

Aesthetics

You can find these antennas in many different designs. Based on the design of your room, you can opt for an antenna of a specific design. The one you pick should suit your office or room.

Functionality

Different wireless antennas have different features. There are wide-band or multi-band designs. A more powerful antenna will be needed should you want a large area covered.

Omni-Directional

These powerful antennas can receive signals at 360 degrees. Typically, you can find these antennas in cell phones and WiFi routers.

Dipole or Directional

As the name implies, these antennas transmit signals in the direction they are pointed to. They have long range and can be an ideal choice if you live in an area that is far away from the place where you want to receive the signals from.

Yagi Antennas

For signal coverage from far away areas, we suggest that you go for yagi antennas. Let’s suppose you want to have WiFi available outside your house. One good option will be to install a yagi directional antenna.

These antennas work well for urban residents residing in quarters as they can save a lot of money. Rather than install multiple other antennas, a couple yagi antennas can do the job.

Cantenna

It’s a popular brand and refers to a do-it-yourself regular or directional antenna. You can use Cantenna antennas both indoors and outdoors.

Now is the time to upgrade your wireless antennas should you experience signal reception problem in your house. After analyzing the site, you may want to install a few more WiFi access points.

As soon as you have upgraded your WiFi antennas, you will notice that your device is working more efficiently. However, it is important to keep in mind that the role of antennas is to help with the concentration of signal. For a significant performance improvement, the radio transmitter has to be as powerful as possible. By keeping all these factors in mind, you can easily opt for the right WiFi antennas to meet your needs.

Founded in 1996, Cirocomm is a leading provider and designer in microwave communication components industry. We provide a large scale of passive 3C components, including dielectric resonators, dielectric filter and wifi antenna etc products. If you need more information about our wifi antennas or other antennas series, welcome to visit the website of Cirocomm to learn further details.

Article Source: http://EzineArticles.com/expert/Jovia_D’Souza/2007086