homework help > electrical engineering > electrical engineering q&a board > topic: help on understanding diodes...

Q BgQuestion:

      
Pupil
Karma Points: 65
Respect (0%):
posted by  yellowdude on 4/9/2006 6:36:44 PM  |  status: Live  |  Earned Karma: 65

help on understanding diodes

Course Textbook Chapter Problem Needs by
Digital Circuits Microelectronic Circuits (5th) by Sedra, Smith 3 63P N/A
Question Details:

The question asks for regulation diodes, and I'm having the worst time understanding the diodes in general: as in which models to use given circuits and such.  Got stuck on part a) even because I'm not too sure how to find Vo with a load connected.  I thought of doing voltage division, but since the voltage is regulated with the diodes, I'm not too sure that's how it works.  If both diodes have voltage drop of 0.7V at current 10mA, with n=1, a)Vo with load connected, b)Vo without load connected etc...
 

Chap3. Prob63

AAnswers:

Answer Question Ask for clarification
Apprentice
Karma Points: 124
posted by SamO on 6/9/2006 5:21:59 PM  |  status: Live
Asker's Rating: N/A-Posted Before Updated Site   
Response Details:

You know the node right above the two diodes has to be 1.4 if the two diodes are on. The load current is then a simple equation 1.4/180. I see this as a trick question, you need to understand that the voltage above the two diodes does not change no matter how many loads you add on. The current would get bigger or smaller depending on how many loads you add/remove. Also since the diodes are in series, they will either always be both off or on. But since the voltage above the 180 resistor is 5V it leads to believe that the diodes are on. However, you can always test this by seeing if current actually flows through the resistor.
Pupil
Karma Points: 57
posted by imaaginarymuffin on 11/5/2009 12:57:12 AM  |  status: Live
Asker's Rating: This answer has not been rated. If you asked this question, then please login.   
Response Details:
Since each diode is conducting and has a conducting voltage of 0.7 V, then the voltage at the node above the diodes is 1.4V (0.7 + 0.7). The load is 150Ω and it is grounded on the other end, therefore the output voltage across the load is (1.4-0)/150Ω. You already know V0 with no load (1.4V - explained above).

Val G.
Answer Question Ask for clarificarion
Ask New Question

Join Cramster's Community

Cramster.com brings together students, educators and subject enthusiasts in an online study community. With around-the-clock expert help and a community of over 100,000 knowledgeable members, you can find the help you need, whenever you need it. Join for free today » How Cramster is different from tutoring »

Need Help In

Useful Links