i found this circuit as it uses light and ldr.. i found too complicated and perhaps wont work properly the circuit is in the attachment but i dont think it is a reliable circuit that can really determine whether the refrigerator door is open or close.
hi sir can you please help me to design a circuit ........ i want to make a circuit that using a ic555timer ,buzer,led,transistor,and relay if possible.
i am aiming to make a circuit that can determine whether or not Refrigerator door is closed properly. i want the buzer to produce sound alert & the led to light up whenever if the Refrigerator door is not closed within within a given amount of time preferably minutes.
is this possible? please help me... please design the circuit for me so that i can learn how a simple circuit can solve this problem

 

i dont think it is a reliable circuit that can really determine whether the refrigerator door is open or close.

What makes you think that?

is this possible?

Yes.

As this is a homework problem, tell us what changes you think would be needed to the posted circuit to meet your requirements.

 

please design the circuit for me

Not a request that is generally well received here in Homework Help.

 

Not a request that is generally well received here in Homework Help.

How about this circuit? I came to the conclusion
Of D for the answer

 

How about this circuit? I came to the conclusion
Of D for the answerView attachment 60861

And what does this have to do with either the OP's question OR the response that you quoted?

 

And what does this have to do with either the OP's question OR the response that you quoted?

Always waiting for someone to mess up arent ya. Well I get an error message everytime I try to post so only way I could post was to reply to a message. I have informed webmaster for the past 4 days but they dont seem to fix the issue.

 

When you have a problem with the forum, you might also try posting something in the Feedback forum (and, if you have to hijack a thread to get something posted, that is the place to do it). If you do hijack a thread, then start your post off by explaining why you are hijacking someone else's thread so that people can understand the context of your post.

The most likely problem is that you are using a thread title that is too long.

See this: http://forum.allaboutcircuits.com/showthread.php?t=81830

See if that helps.