What is a Fuse ? And how to test it.

Written by Jestine Yong

A fuse is a very thin wire, which either melts or vaporizes when too much current flows through it. The thin wire may be made of aluminum, tin-coated copper or nickel. The resulting open inrepparttar circuit stops current flow. In electronic equipment, most fuses are cylindrical glass or ceramic type with a metal cap at each end! The current rating also can be seen in one ofrepparttar 138978 two metal end caps. There are two popular physical sizes: 1 – ¼ X ¼ - inch and 5X20mm. The 1 – ¼ X ¼ - inch size is used in many automobiles. You’ll find both sizes in many electronic equipment, butrepparttar 138979 smaller 5 X 20mm has become more common. Fuses are available with current ratings from 1/500 Ampere to hundreds of amperes.

Purpose of Fuses

The purpose of a fuse is to open an electronic circuit when current flow exceeds a certain amount, determined byrepparttar 138980 rating ofrepparttar 138981 fuse. Opening a circuit under high current conditions can save electronic components from damaged and prevents overheating, which could cause a fire.

Types of Fuses

There is two basic types of fuses: fast acting and slow blow. The fast acting type will open very quickly when their particular current rating is exceeded. This is important for analog meter movements, which can quickly be destroyed when too much current flows through them, for even a very small amount of time. Slow blow fuse have a coiled construction inside. They are designed to open only on a continued overload, such as a short circuit. The purpose of coiled construction is to preventrepparttar 138982 fuse from blowing on just a temporary current surge.

Do not use a slow blow fuse in place of a fast acting fuse. It may not open fast enough to prevent components damage under a high current condition. It’s not harmful to replace a slow blow fuse with a fast-acting fuse, but it will probably open up unnecessarily every now and then whenrepparttar 138983 equipment is first switch on. A blown fuse can tell you something about your service problem. Oftenrepparttar 138984 glass case ofrepparttar 138985 fuse appears clear, and you can still seerepparttar 138986 broken pieces ofrepparttar 138987 fuse element. This means you haverepparttar 138988 kind of problem that causes a slow, gradual overload onrepparttar 138989 power supply. Some fuses even die of old age. But ifrepparttar 138990 inside ofrepparttar 138991 glass fuse is discolored, and there is no trace ofrepparttar 138992 fuse element (the center connector), you know thatrepparttar 138993 center connector was destroyed quickly and violently, using a lot of heat. The fault was a short circuit or other problem that caused a lot of current to flow very quickly.

What is a crystal ? And how to test it.

Written by Jestine Yong

Crystal are use to keeprepparttar frequency ofrepparttar 138977 clock from drifting. Ifrepparttar 138978 signal from this clock stops, or is weak, orrepparttar 138979 pulses begin to vary,repparttar 138980 electronic equipments might show intermittent faults or might stop altogether. The microprocessor pins that holdrepparttar 138981 crystal are usually called OSC IN and OSC OUT as shown in Figure 1 andrepparttar 138982 frequency is marked onrepparttar 138983 crystal. Typical examples of crystal oscillator frequency are 3.58MHZ, 4MHZ, 8MHZ, 24MHZ etc.

Testing Crystal Crystals are quite fragile components because of their construction. Unlike a resistor or capacitor, if you drop one onrepparttar 138984 ground from a decent height, its 50-50 bet whether it will work again. Testingrepparttar 138985 crystal is not a breeze either. You cannot just take out your trusty multimeter and plugrepparttar 138986 crystal in it. In fact, there are three right ways to test a crystal: -

(a) Using Oscilloscope A crystal produces a sine wave when excited. It is appropriate then, to see a waveform representative of a sine wave onrepparttar 138987 clock pins. Ifrepparttar 138988 clock is not functioning properly, replacerepparttar 138989 crystal. In most cases this should solverepparttar 138990 problem since microprocessors are usually very reliable. Checkrepparttar 138991 crystal with power on.

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