problem in diode circuits

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Bhuvanesh123

i dont know how to ensure that two diode are conducting .my professor said to remove the diodes and find the current direction ,if the current direction of branch matches with reference current direction of diode then it is on else it is off.Is that way to ensure the conduction of diode or any other way we have

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biswaIITH

Full Member level 3
Measure the voltage across the diodes..it must have some forward voltage drop across though small in magnitude

betwixt

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Measure the voltage across the diodes..it must have some forward voltage drop across though small in magnitude
That will only work if the diode is carrying DC. If it is in a rectifier circuit the polarity may be reversing so the result on a normal voltmeter would be inconclusive.

Your professor gave the best solution although in most circuits it would be obvious if the diode wasn't conducting. You could connect an oscilloscope across it and measure the voltage across it, the forward voltage should be Vf as mentioned in the data sheet, the reverse voltage will not be limited to Vf so it could be higher. Beware that some kinds of diode, for example a Zener diode might be expected to conduct in both directions although not with the same voltage drop each way.

The real solution is to ask your professor what kind of diodes they are and what the application is.

Brian.

ravindragudi

Full Member level 3
Simple way to remember the direction of current conduction in the diode is the diode symbol in the circuit. The symbol triangle with a vertical bar looks like an arrow. This arrow direction is in which the current through the diode flows when the diode conducts.

Audioguru

Simple way to remember the direction of current conduction in the diode is the diode symbol in the circuit. The symbol triangle with a vertical bar looks like an arrow. This arrow direction is in which the current through the diode flows when the diode conducts.
Conventional current direction or electron current direction? When you talk about current direction then you must say which type of current to avoid confusion.
I never talk about current direction, I simply say that when the anode (the triangle symbol) is positive and the cathode (the bar symbol) is negative then the diode conducts.
The same with a bipolar transistor, I do not talk about current direction. On an NPN transistor if the P (base) is positive and an N is negative then the diode conducts. On a PNP transistor if the N (base) is negative and a P is positive then the diode conducts.

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