# help

Discussion in 'Homework Help' started by beemovie, Dec 19, 2008.

1. ### beemovie Thread Starter Member

Dec 19, 2008
12
0
Today I have encountered another problem please help me solve it !!! I am still a beginner !!!

1)The maximum current that a silicon diode can handle is 300mA. The diode is connected in series with a resistor across a D.C supply of 12V.
Can this diode be connected in a similar circuit using the same series resistor but having a DC supply of 100V instead ?

Explain in detail by making the necessary calculations....

1b)If your answer to question 1 is no, what can be the remedy to the problem ???

10X

2. ### Audioguru New Member

Dec 20, 2007
9,411
896
Why do you heat a resistor and a diode with 12V?

If the current with a 12V supply is 300mA then the current with 100V is almost 9 times higher.

The diode has a forward voltage of about 0.9V at 300mA. Then for 300mA with a 12V supply the resistor value is (12V - 0.9V)/300mA= 37 ohms.

The forward voltage of the diode with 9 times more current is about 1.5V. Then with a 100V supply, the current is (100V - 1.5V)/37 ohms= 2.66A.

Apr 5, 2008
15,805
2,389
Hello,

If this is also a school question, it is best placed in the homework help section !

1A) if the current is limited to 300 mA on 12 Volts, the diode will not survive the 100 Volts.
The current will be to high as Audioguru already told you.

1B) Make the resistance higher, you can calulate how high it should be.

Greetings,
Bertus

PS make use of a better tilte than just HELP.