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What is the need of resistor in the experiment of pN junction diode?
Wiki User
∙ 13y ago
The resistor limits current so you can measure voltage across the diode. When you forward bias and saturate a junction, the voltage across it will be constant (0.7 in silicon, for example).
Wiki User
∙ 13y ago
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What is the supply for a diode?
The diode voltage drop is 0.7 volts, so you need that much to turn it on. Current is controlled by a resistor in series.
Germanium diode works at 0.3v?
To forward bias a germanium diode you need to reach between 0.2 and 0.3 V between anode (+) and cathode (-). Once this voltage is reached, the diode will conduct. Make sure you have a resistor to limit the forward current to a safe (for the diode, that is) value.
If I am given a circuit made of a diode a surge resistor and a DC source with which you can easily reverse the polarities what instruments do I need to know if the diode operates properly or not?
Any of these: Voltmeter: Across the Resistor, Vmax when diode conducts, 0 when you switch polarity Across the diode Vmin when conducting, Vmax when not. Ammeter: in series with ckt, Amax when conducting Amin when not, etc. Ohmmeter: No power required. Lo R one way, Hi R when leads reversed
Is it possible to make a junction diode by pressing two pieces of n type and p type together?
No, a functioning junction diode cannot be made by placing two oppositely doped pieces of semiconductor in contact with each other. A functioning junction diode can only be created in one piece of semiconductor with oppositely doped regions in it.However if you placed the two oppositely doped pieces of semiconductor in contact with each other and HEATED them until they just began to melt and joined becoming one piece, it is possible to create a functioning junction diode this way. But this is a tricky and not very reliable way to do it, especially if you melt it just a tiny bit too much you will completely mix the two pieces and lose the doping entirely.
How do you test a light emitting diode?
You can test it by puting it in forward bias with a resistor. Use a dc voltage source of 5 volts and put it in series with 250 Ohms resistor. Or use 9volts with a 450 Ohms resistor. Basically you need 20mA of forward current usually. Smaller current will reduce brightness.
Can you use transistor as diode?
its the simplest thing to do. There are three legs in a transistor, one each of collector, base and emitter. So if you need to use it as a diode, just connect either collector-base or emitter-base. Say, if you use an NPN transistor, then the base region will be the anode of diode and emitter or collector will be the cathode of the diode.
What value resistor and diode would you need to drop voltage from 12 volts ac to 1.2 volts dc?
I'm not sure you understand what you're asking. A diode will have a voltage drop of ~.5-.7 volts. If you put a diode and resistor in series, the voltage across the diode will be .5 - .7 volts, and the voltage drop across the resistor will be (supply voltage - diode voltage drop). If you are trying to rectify to DC, you need at the least a half wave rectifier (two diodes), and some system to remove the ripple. The rectifier simply chops the AC waveform, so for the part of the supply sine wave that is ~.5 or less, the output of the rectifier will be zero. The top part of the sign wave will show up on the output of the rectifier, but will be slightly smaller (due to the voltage drop across the diode). You'll need to get ride of this rippling for true DC. One fairly easy way to do this is to use a zener diode. It will attempt to keep the voltage drop across it the same, so purchase a 1.2 volt zener diode. The problem with this is the zener diode will saturate if you have too heavy a load. What I've done on simple projects is to use a zener diode to bias the base to collector voltage of a transistor, with the emitter acting as the output (an NPN BJT usually). I also used a fairly large capacitor to help minimize the ripple as well, although this may not be necessary for you.
Can you use transistor as a rectifier?
No, a Transistor operates with a modulated direct current. You need 4 Diodes to manufacture a rectifier to deliver direct current at the outlet, with alternating current at the input. A Diode is effectively a one way valve to address one halve of the cycle of the alternating current.
What are the basics of how flashlights work?
You need a conductor, power source and a resistor. You need a conductor, power source and a resistor. You need a conductor, power source and a resistor.
How do you find the value of a zener diode?
It is depend on your requirement .suppose you need a voltage regulator of 5V than you need 5V Zener diode.
What is pn junction capacitance?
The charge inside of a p-n diode with a connected voltage variety yields a capacitance is need to add circuit model of a p-n diode. The capacitance connected with the charge variety in the exhaustion layer is known as the intersection capacitance, in the same process capacitance connected with the abundance bearers in the semi impartial district is known as the dissemination capacitance.
Why do some circuits need resistors?
A circuit does need resistance but not necessarily a resistor. without any resistance a circuit will be considered a "short circuit" and you power source will most likely overheat. Resistance can be created in millions of different ways. This could be something such as an or any other light source but also a module such as a capacitor resistor or diode. To get to you're question more directly a circuit needs resistance to keep from shorting out. A specific module(such as an LED) would need a resistor to lower the voltage so to a point where the module can accept the power without burning out.
