Engineering Easy zener diode circuit questions

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The discussion revolves around calculating the current in a zener diode circuit with supply voltages of 10V and 15V. For the 10V supply, the calculations initially suggested that the zener current is 0A, but it was clarified that the zener voltage should be 5.1V, leading to the conclusion that the zener does not conduct. The correct approach involves checking if the zener can operate based on the voltage across it, which is less than its breakdown voltage in this case. The participants emphasized the importance of stating both the zener and load currents explicitly in calculations to receive full credit. Ultimately, understanding the zener's operational limits is crucial for accurate circuit analysis.
  • #31
nothing909 said:
I don't understand what you mean. :/
If your load current is 5 mA, what is the voltage V1 in the following diagram?
upload_2016-11-5_16-45-18.png


nothing909 said:
Can I ask one more question about this circuit. What is zener voltage supposed to be? 9.1?
Yes.
 
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  • #32
gneill said:
If your load current is 5 mA, what is the voltage V1 in the following diagram?
View attachment 108524Yes.
The voltage is 5V.

And just quickly about that second circuit, just so I know this is correct. The reading on the voltmeter would be 9.1V and the reading on the ammeter would be:

Voltage across resistor = 20 - 9.1 = 10.9V

Reading on ammeter = 10.9/10000 = 1.09mA
 
  • #33
nothing909 said:
The voltage is 5V.
Correct. Which is less that the zener voltage of 5.1 V. So the zener placed there would not conduct. That's the test I was urging you to carry out.
And just quickly about that second circuit, just so I know this is correct. The reading on the voltmeter would be 9.1V and the reading on the ammeter would be:

Voltage across resistor = 20 - 9.1 = 10.9V

Reading on ammeter = 10.9/10000 = 1.09mA
Yes, that looks good.
 
  • #34
gneill said:
Correct. Which is less that the zener voltage of 5.1 V. So the zener placed there would not conduct. That's the test I was urging you to carry out.

Yes, that looks good.
okay, great, thanks very much for all your help. :)
 

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