electric circuits

Diode’s recognition is very simple, low power diode’s N (cathode), mostly uses one kind of color circle in the diode semblance to section out extremely, some diodes also use the diode special-purpose mark to express P extremely (positive electrode) or N extremely (cathode), also has uses the sign flag is “P”, “N” determines the diode polarly. The light emitter diode positive and negative may distinguish extremely from the pin length, long foot for positive, short foot for negative.   1: Crystal diode’s recognition methods and function   The crystal diode commonly used “D” adds the digital presentation in the electric circuit,electric capacity
for example: D5 expressed that the serial number is 5 diodes.

1st, function: Diode’s principal characteristic is the unilateral conductivity, is also under the direct voltage function, the breakover resistance is very small; But under reverse voltage function breakover resistance enormous or infinity. Because just the diode has the above characteristic, in the non-rope telephone often it uses, in the rectification, isolates, the constant voltage, the polar protection, the encoded control, the frequency modulation modulation and static chirp and so on the electric circuits.

In the telephone uses the crystal diode may divide into according to the function: Rectification diode (for example 1N4004), isolating diode (for example 1N4148), Short base diode (for example BAT85), light emitter diode, zener diode and so on.

2nd, recognition methods: Diode’s recognition is very simple, low power diode’s N (cathode), mostly uses one kind of color circle in the diode semblance to section out extremely, some diodes also use the diode special-purpose mark to express P extremely (positive electrode) or N extremely (cathode),accommodates
also has uses the sign flag is “P”, “N” determines the diode polarly. The light emitter diode positive and negative may distinguish extremely from the pin length, long foot for positive, short foot for negative.

3rd, test matters needing attention: Measures the diode when with the digital avonmeter, the red table pen meets diode’s positive electrode, the black table pen meets diode’s cathode, this time obtains the resistance number is diode’s forward breakover resistance number, this and the indicator type avonmeter’s table pen connection is just opposite.

In diode inspection common bad item

The diode expects in the inspection the common bad item mainly to have: The packing distorts, the breakage; Indicates unclear or does not have the indication, the errors and omissions; Most, minority; Size and specification not symbol; The diode main body damages;voltage elevates
The pin pine, breaks, the oxidation; The polar indication is not clear about, the polarity instead; The puncture short-circuits, the internal opening; The photo tube is nonluminous, is dark; The stabilovolt constant voltage value is high somewhat low;

Test matters needing attention: Measures the diode when with the digital avonmeter, the red table pen meets diode’s positive electrode, the black table pen meets diode’s cathode, this time obtains the resistance number is diode’s forward breakover resistance number, this and the indicator type avonmeter’s table pen connection is just opposite.

Using diode’s unilateral conduction characteristic, may use the amp to measure that its forward and reverse resistance, judges its quality. The test method is puts in the indicator type amp R×100 the files or R×1k the files, measured that diode’s resistance, then replaces the red table pen and the black table pen measured again. If two times obtains as soon as the resistance one big is small, and big that one time tends the infinity, may conclude that this diode is good. Simultaneously may also conclude the diode both sides positive and negative. Namely when obtains the resistance number is small, the black table pen meets that end namely for diode’s positive electrode.

1st, rectification diode Hotel interior design contemporary style Using the diode unilateral conductivity, may the exchange transistor diode mark which and the material object changes alternately the direction transforms the sole direction the pulsating direct current.   2nd, on-off element

The diode the resistance is very small under the direct voltage function, is at the conducting state, is equal switch which puts through in one; Under the reverse voltage function, the resistance is very big, is at the closure condition, is similar to switch which separates. Using diode’s switch characteristic, may compose each logic circuit.

3rd, restricts the part

After diode forward breakover, its forward voltage drop maintains basically invariable (silicon tube is 0.7V, germanium tube is 0.3V). Using this characteristic, the achievement restricts the part in the electric circuit, may the signal scope limit based on this.

4th, following class diode   In switching power supply’s inductance neutral relay and so on perceptual in loads following class function.

5th, detector diode   In radio detecting action.   6th, varactor   Use in television’s high frequency tuner.

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