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Why does a diode not conduct until the cut in voltage is reached?
Wiki User
∙ 12y ago
Cut in voltage is the minimum voltage required to overcome the barrier potential.
In other words it is like trying to push a large boulder....it may not be possible to push a large boulder by one person but it may be done if 2 or more people try to push it together depending on the size of the boulder.....similarly....the charge carriers in the barrier region have a potential energy of about 0.6V for Silicon and about 0.2V for Germanium. so in order for the diode to conduct, it is required to overcome the potential of the charge carriers in the junction barrier region and hence only if a potential more than that of the barrier potential (cut off voltage) is applied, then electrons flow past the junction barrier and the diode conducts.
Wiki User
∙ 12y ago
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What is a zener diod?
A Zener diode is a type of diode that sends current in the forward way like a normal diode, but also in the reverse direction if there is voltage that is larger than the breakdown voltage which is also known as "Zener voltage". The apparatus was named after Clarence Zener, who discovered this electrical property.
Why you use diode in the circuit?
It depends on the type of diode. Generally, diodes are use for converting AC supply to DC. That is particularly true of silicon rectifier diodes. Germanium detector diodes are used in radios to detect the signal from the RF. Those same types of diodes are useful in logic circuits as well. They don't handle a lot of voltage or current, but they work fine with radio and computer signals. A zener diode functions much like an ordinary diode until a breakdown voltage is reached, and then it will conduct the other direction, making it useful for voltage regulation. For instance if a zener is placed across some DC power leads after a fuse, then the unit may be protected from both excessive voltage and being hooked up backwards. If the device is connected to the DC source with the correct polarity, and if the voltage is not beyond the rated value, the diode will not conduct, and thus not blow the fuse. A light-emitting diode is used primarily for producing light. Arrays of LEDs are used in displays, televisions and computer monitors. Even home and commercial lighting now uses LED technology.
What will a Zener diode do at breakdown voltage?
A Zener Diode will continue to show its breakdown characteristics until it gets fried...for example a 5 volt zener will get fried at a breakdown voltage of about 6 volts..this happens because of the large amount of current flowing through the small diode which unfortunately the diode cannot handle.
What is the input voltage at which a diode will pass current?
As close to virtually zero volts as is possible: the current will very small but there will be current. This depends on two things: the material that is used to make the diode, and whether the voltage is applied in a forward or reverse direction to the diode. A typical silicon diode will pass forward current above 0.6 V and pass no reverse current until a much higher voltage is applied (check the rated peak inverse voltage PIV)
What are the voltage and current characteristics of a series circuit?
The voltage and current characteristics of a zener diode in the forward bias condition (anode more positive than cathode) are similar to an ordinary diode. Below the cutoff voltage, the current is near zero, excepting for leakage current. Starting at the turnon voltage, the diode starts to conduct. As voltage increases, current increases. At this point, increases in current result in very small increases in voltage. Above the breakdown current, the diode tends to self-destruct. The cutoff voltage for a silicon diode typically ranges from 0.6V to 0.7V, and the beginning of the flat region ranges from 0.7V to 1.4V, depending on the current rating of the diode. The cutoff characteristic is also highly dependent on temperature. It is important to understand that, while the current to voltage curve is relatively flat between the cutoff and breakdown points, it is not completely flat. This is normal diode behavior. In the reverse bias condition (anode more negative than cathode), the zener diode behaves very much like its forward bias condition, except that the cutoff voltage and flat region range are higher and, sometimes, flatter. This is what a zener is used for - it makes a good voltage regulator.
What is the zener region?
The zener region describes the area on the performance curve (a graph of voltage across versus current through the junction) of a zener diode. The diode acts like a "regular" diode in the forward biased direction. When some 0.7 volts or so is reached, forward current begins to climb rapidly as voltage is increased (for silicon diodes.) But in the reverse direction recall that as the diode is reverse biased, a small amount of current will flow (because of minority carriers). This "trickle" of current will continue until the "zener voltage" is reached, and then the diode will begin to conduct heavily. On the graph, this is the zener region. Zener diodes can be made to breakdown at a specific voltage, and their ability to conduct reverse current can be increased by manufacturing a larger diode. That means there are a range of voltages and wattages of zener diodes available. Wikipedia has more information and that graph. Use the link provided to get there.
Why is a thyristor good in a circuit?
IT IS A RECTIFIER but by adding a gate it becomes a control diode rectifier it will conduct when there is appropriate voltage on the plate and gate. will however not shut off not until the holding current is reached irregardless of gate control;
Voltage of a diode at which current increases?
In a Silcon diode no current flows in the forward direction (anode to positive voltage) until approximately 0.6 - 0.7Volts is reached. Above this voltage the current rises in line with Ohms Law. In the reverse direction only micro Amps flow (leakage current) In a Germanium diode the threshold is about 0.2 volts and reverse leakage is higher.
What is a thyrector diode?
A Thyrector is essentially two zener diodes connected back-to-back in opposing polarity which means it will not conduct until an over-voltage above its break-down voltage rating occurs. This is used to trap voltage spikes and suppress them.
What is a zener diod?
A Zener diode is a type of diode that sends current in the forward way like a normal diode, but also in the reverse direction if there is voltage that is larger than the breakdown voltage which is also known as "Zener voltage". The apparatus was named after Clarence Zener, who discovered this electrical property.
How do you connect a diode across a 24 volt valve?
Use of a diode across a DC electromagnetic device, such as a valve, is to counter the reverse voltage (EMF) caused by the collapse of the magnetic field when the power is turned off. If the diode were not present, the reverse voltage can become very large, even to thousands of volts or more, and it can damage the associated circuitry. In this application, the anode is connected to the negative side, and the cathode is connected to the positive side. When power is applied, the diode does not conduct. When power is removed, and the inductor attempts to maintain the current flow by generating a reverse voltage, the diode conducts until the magnetic field collapses.
Why you use diode in the circuit?
It depends on the type of diode. Generally, diodes are use for converting AC supply to DC. That is particularly true of silicon rectifier diodes. Germanium detector diodes are used in radios to detect the signal from the RF. Those same types of diodes are useful in logic circuits as well. They don't handle a lot of voltage or current, but they work fine with radio and computer signals. A zener diode functions much like an ordinary diode until a breakdown voltage is reached, and then it will conduct the other direction, making it useful for voltage regulation. For instance if a zener is placed across some DC power leads after a fuse, then the unit may be protected from both excessive voltage and being hooked up backwards. If the device is connected to the DC source with the correct polarity, and if the voltage is not beyond the rated value, the diode will not conduct, and thus not blow the fuse. A light-emitting diode is used primarily for producing light. Arrays of LEDs are used in displays, televisions and computer monitors. Even home and commercial lighting now uses LED technology.
What will a Zener diode do at breakdown voltage?
A Zener Diode will continue to show its breakdown characteristics until it gets fried...for example a 5 volt zener will get fried at a breakdown voltage of about 6 volts..this happens because of the large amount of current flowing through the small diode which unfortunately the diode cannot handle.
When voltage changes from forward voltage to reverse voltage junction voltage cannot change?
A: THAT IS CORRECT a diode conducts only one way that is why it is called a semiconductor Reversing the voltage no current will flow until breakdown.
What is the input voltage at which a diode will pass current?
As close to virtually zero volts as is possible: the current will very small but there will be current. This depends on two things: the material that is used to make the diode, and whether the voltage is applied in a forward or reverse direction to the diode. A typical silicon diode will pass forward current above 0.6 V and pass no reverse current until a much higher voltage is applied (check the rated peak inverse voltage PIV)
What are the voltage and current characteristics of a series circuit?
The voltage and current characteristics of a zener diode in the forward bias condition (anode more positive than cathode) are similar to an ordinary diode. Below the cutoff voltage, the current is near zero, excepting for leakage current. Starting at the turnon voltage, the diode starts to conduct. As voltage increases, current increases. At this point, increases in current result in very small increases in voltage. Above the breakdown current, the diode tends to self-destruct. The cutoff voltage for a silicon diode typically ranges from 0.6V to 0.7V, and the beginning of the flat region ranges from 0.7V to 1.4V, depending on the current rating of the diode. The cutoff characteristic is also highly dependent on temperature. It is important to understand that, while the current to voltage curve is relatively flat between the cutoff and breakdown points, it is not completely flat. This is normal diode behavior. In the reverse bias condition (anode more negative than cathode), the zener diode behaves very much like its forward bias condition, except that the cutoff voltage and flat region range are higher and, sometimes, flatter. This is what a zener is used for - it makes a good voltage regulator.
How do you connect diodes in series?
Connect positive to negative, leaving the end positive and negative connections free to power circuits or devices. Connecting batteries in series adds the voltage of the batteries. For instance, connecting three 12v car batteries in series will create a total of 36v, enough for welding.
