Solving Zener Diode Problem - Need Help

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In summary, the conversation discusses how to calculate the value of a resistor in a circuit with a 15 volt supply and a load resistor. The minimum current for the Zener and the current in the load are known, allowing for the calculation of the total current in the series resistor. The voltage across this resistor is also known, enabling the selection of an appropriate resistor. The conversation also mentions checking the Zener power rating to ensure it is not being exceeded.
  • #1
waihung
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Homework Statement



Please refer to the picture
[PLAIN]http://img337.imageshack.us/img337/7118/46864828.jpg

Can anyone help me?
Thanks.
 
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  • #2
You can work out the value of the resistor when the load is connected, but there is only a 15 volt supply.

You know the minimum current for the Zener and you know the current in the load (it has 10 volts across it) so you know the total current in the series resistor.
You know the voltage across this resistor so you can work out what size resistor it should be.

So, you can select this resistor and see how it affects the currents when there is a 20 volt supply and/or there is no load resistor.

Notice that the Zener will take whatever current is necessary to maintain the output voltage at 10 volts.

Then check if the Zener power rating is being exceeded.
 

Related to Solving Zener Diode Problem - Need Help

1. What is a Zener diode and how does it work?

A Zener diode is a type of semiconductor diode that is designed to operate in the reverse breakdown region. This means that when a certain voltage, known as the Zener voltage, is applied in the reverse direction, the diode starts to conduct current. This allows the Zener diode to regulate voltage and protect circuits from voltage spikes.

2. How do I calculate the Zener voltage for a specific diode?

The Zener voltage is typically listed in the datasheet for a specific diode. If it is not listed, it can be calculated by measuring the voltage across the diode when a known current is applied in the reverse direction. The Zener voltage is equal to this reverse voltage.

3. What are some common problems when using Zener diodes?

One common problem with Zener diodes is that they can be damaged if the reverse voltage is exceeded. This can happen if the diode is connected in the wrong direction or if the voltage spike is higher than the Zener voltage. Another problem is that Zener diodes have a temperature coefficient, meaning that their Zener voltage can change with temperature.

4. How can I troubleshoot a Zener diode circuit?

If a Zener diode circuit is not working as expected, the first step is to check that the diode is connected correctly and that the Zener voltage is appropriate for the circuit. If the diode is damaged or the voltage is incorrect, it may need to be replaced. Additionally, checking for any short circuits or incorrect connections in the circuit can help identify and fix the problem.

5. Can I use Zener diodes for other applications besides voltage regulation?

Yes, Zener diodes can also be used for other applications such as voltage clamping, voltage reference, and voltage limiting. They can also be used in combination with other components to create more complex circuits such as oscillators or amplifiers.

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