Advice 1: How to ring a field-effect transistor

During the repair of electronic equipment are sometimes required to test a field effect transistors. These semiconductor devices in most cases operate as a powerful key device. Sometimes it happens that they fail.
How to ring a field-effect transistor
You will need
  • - A multimeter or ohmmeter.
Instruction
1
Test of field transistor, when it is soldered to the electronic circuit does not work, so before checking wipaire it. Inspect the enclosure. If the case has a hole from the melting of the crystal, test the transistor makes no sense. If the housing is intact, you can proceed to checkout.
2
The vast majority of powerful field transistors have a structure of MOS-FET and n-channel insulated gate. Less common are p-channel, mainly in the terminal stages of audio amplifiers. Different structures of field effect transistors require different means for their verification.
3
Vypav transistor, allow it to cool.
4
Put the transistor on a dry sheet of paper. Insert the wires of the ohmmeter to the red positive connector and the black to negative. Set the measurement range to 1kω. The channel resistance of an open transistor depends on the voltage applied to the gate relative to the source, so in the process of working with a transistor, you can set a convenient scale. The connection of the electrodes inside the housing shown in the photo.
5
Touch the black probe to the electrode of the source transistor, and the red touch the electrode "sink." If the device shows a short circuit, remove the test leads and connect all three electrodes with a flat head screwdriver. The goal is to discharge capacitive transition of the shutter, perhaps it was loaded. Then repeat the resistance measurement channel. If the instrument still shows a short, then the transistor is faulty and must be replaced.
6
If the device showed a resistance close to infinity, then check the transition of the shutter. It is checked similar to the transfer channel. Tap any probe electrode of source transistor, and the other touch the electrode "shutter". The resistance must be infinitely large. Insulated shutter electrically connected to the channel of the transistor and any discovered resistance in this circuit indicates a fault of the transistor.
7
The test procedure is fully serviceable transistor looks like this: Touch the black probe of the ohmmeter to an electrode of source transistor, touch the red probe of the electrode "shutter". The resistance must be infinitely large, and then, without closing the "gate" to other electrodes, touch the red probe electrode "sink." The instrument will show little resistance in this area. The magnitude of this resistance depends on the voltage between the ohmmeter probes. Now touch the red probe electrode Istok, repeat the above procedure. The channel resistance is very high, close to infinity. A method of testing MOS-FET transistor p-channel is characterized in that the measurements need to switch the red and black probes of the ohmmeter.

Advice 2: How to test the transistor tester

Some testers have built-in meters gain of low power transistors. If you device does not have the faulty transistors to check conventional tester in ohmmeter mode, or by using a digital tester mode diode test.
How to test the transistor tester
Instruction
1
To check bipolar transistors connect one probe of multimeter connect to the base of the transistor, the second probe hold alternately to the emitter and the collector, then adjust the probes sometimes repeat the same steps. Please note that the inside of the electrodes many digital or powerful transistors can be placed in protective diodes between collector and emitter and built-in resistors between base and emitter or in the base circuit if you do not know, by mistake, may find the item is faulty.
2
When testing field - effect transistors consider the fact that they come in a variety of types. For example, the test transistorswith the shutter on the basis of the isolation layer p-n junction, is. Take an ordinary analog or digital ohmmeter (the second is more convenient).
3
Measure the resistance between the drain and the source, it must have a small size and be approximately equal in both directions. Now measure forward and reverse resistance of the junction, to do this, connect the test probes to the gate and drain (or source). If the transistor is good, the resistance will be different in both directions.
4
When I check the resistance between the drain and the source, remove the charge from the gate for this for a couple seconds, close it with the source, if you do not – you will get a unique result. Most low-power field - effect transistors are extremely sensitive to static. Therefore before to take the transistor in hand, make sure that your body is not left charges. To get rid of them, touch the hand of any grounded instrument (battery heating). Powerful field-effect transistors are often equipped with protection against static, but despite this protection when working with them won't hurt.

Advice 3: Why wildflower is called "Ivan da Marya"

Beautiful and romantic name field of the flower Ivan-da-Marya is associated with the ancient Slavic legends about the forbidden and unbreakable love. This flower was collected in, among others, in the Midsummer night and used for various ceremonies.
Why wildflower is called "Ivan da Marya"

What is a wild flower called Ivan-da-Marya



In fact, this name referred to several completely different plants belonging to different families. Therefore, it is difficult to say exactly what the flower was called so by our ancestors. In any case, it is known that this name has a two-tone flower, usually yellow with purple.

Most often Ivan-Yes-Marja called the plant, known in botany as mariannick Asherah – an annual wild plant, featuring bright yellow flowers with purple bracts. Other names of this plant – Ivanova grass, brother and sister.
Sometimes Ivan-Yes-Marja's name is also the viola tricolor (Pansy) or meadow sage, at least – the periwinkle.


The legend about Ivan-da-Marya



The most common version of the legend explaining the name of the flower, is associated with the name of Ivan Kupala.

Born sometime in the same family twins boy and girl, Kupala and Kostroma. When they were young children, Kupala carried to the far edges of the bird Sirin. Many years later, the young man floated down the river in a boat, wandering in a strange land. That hour past his boat sailed the maiden wreath. Midsummer found him, and went down to the shore, and met his mistress, the beautiful Kostroma. Young people with all my heart fell in love with each other. They were married on Slavic custom. And only then came to his native village, learned that have a family for each other brother and sister.
According to one version of the legend, the gods cursed the Kostroma and Kupalo in their forbidden love, drawing them into flower. According to another version, the star-crossed lovers themselves asked the gods to never be parted.


Another version of the legend tells that Kostroma, unable to endure the shame, walked into the river and turned into a mermaid, Mara.

The brutal legend tells the story of a sister who tried to seduce his brother, and was killed. Before her death she asked to put this flower on her grave.

A "soft" story about a brother and sister who lived on the banks of the river. One sister lured mermaids and turned to Mara, the wife of the water. Then her brother gathered sagebrush-grass, and with her help defeated the water.

The symbolism of plants



Ivan-da-Marya – one of the main symbols of the holiday of Ivan Kupala, a sign of unbreakable love.

In addition, it is believed that the yellow color symbolizes the fire, and violet – water (dew). Thus, Ivan-da-Marya is a symbol of unity of opposites, a sign of fire and water.
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