12V DC Input Monitoring Circuit With Buzzer & LED Alert When Input A Fails

I need help on one of my friend's project in his studies. Project is : Two 12 volt DC inputs named A and B given, if A input goes off then a buzzer and small LED is switched on and if A input comes back the buzzer and small LED is switched off. Please help with diagram so that I can tell perfectly. I am like beginner level in electronics

Quote , "I need help on one of my friend’s project in his studies" , "I am like beginner level in electronics" that’s what studying is all about my friend The whole idea is you go away and find out for yourself In other words you research the topic use the net and then present possible answers to a forum such as this , subsequently telling us from your uploaded diagrams etc or some type of effort , flow charts , diagrams etc that you have made , what it is you don’t understand and then we assist but we don’t give out the answers

That’s why you have to go to college and we don’t See we’ve been through all this before and we all have many years experience to know when you are cheating And that you are at the moment Yes You are , “Cheating this is called “

Fanged !!! Correct Fanged !! caught bang to rights

See when people don't know they do this on net. I am not a student. Student is a friend and I want to help. Please help otherwise he will be on low profile. I request. I am a software developer and m website is ravapps.com. This is for help as he is busy on other subjects.

Doesn’t make any difference That’s also part of studying learning time how to use time slots and allocate time to certain subjects and how to utilize time slot allocation for projects This all part of a degree otherwise wed all have degrees wouldn’t we ? So it may sound mean and unfair but its not This is one of the main reasons why Industry is failing as well Its because of people who think they can use you to do their homework for them whilst they sit on their backsides doing nothing

Most important of all Its unfair to you It also means they have no real respect for you as a person or a friend !! Think about this seriously

How many business do you see failing because they have someone sitting in a management position who doesn’t know how to organize, doesn’t know his / her subject and then blames everyone else when it goes wrong

Far to many hence Don’t do it Turn round and say , Honestly have some guts and say , " Look this is your assignment not mine therefore you go away and do the work yourself that easy " Nothing to this at all

May not like you may not talk to you but they will at least not try and ever use you again In otherwords if you have you tell them then very politley yousay in not so many words < " make a sexual departure "

In more laymans terms , "get stuffed "

I do exactly the same with some of them including bussineses I dont care what they think when I get this stage I tell them where they can go and get off and i mean it from the bottom of my heart so Im quite kind really

If they really get to much I actually tell them stuff the job where the sun doesent shine anymore Im not your skivvy and i leave them standing unable to do a thing about it It works because then they think twice

If you think about this further the reason why they are requesting you do the work is because they bloody well cant do it themselves otherwise they wouldnt be calling you out would they ?? Think about this very very hard



You are spoilt for choice when you have a number of skills behind you

You don’t have to work for anyone at all You can make your own choice and pick who you want to work for and who you don’t who you whish to employee who you don’t That is also freedom of choice Who you will help who you wont that’s what I call freedom of choice and its not just down to qualifications its down to experience and who does respect you and who doesn’t

Attitude in other words My attitude is dependant on theirs and visa versa They decent to me I’m decent back that simple

Rich ,poor or otherwise

They help me I help them, they do a dirty on me I do a dirty on them



Finally if they are that persistent which they can be at times what you do is give them all the wrong answers !! That’s what you do then they will also never try that on with you again and you make it public as well

They will soon get the message that I can assure you of

That also works very well and you can have the last laugh with all of them So if in you feel that you are being put into that position , pressured , if f answer one doesn’t work play dumb , finally screw the job up deliberately and sit back and watch this lot go bezerk !!

You can have such a good laugh with this lot

Once you work this out which I do as well with some of them I now suggest something which I know will work

If they choose not to listen I deliberately let them carry one until they stuff themselves up which you will also work out , but what you also do is use that brain of yours

You only mention this once or twice and then don’t bother to say anymore at all and let them get on with it Let them stuff up the works no point in arguing with some of them and make notes of all of what you are coming up against provide solutions suggest them

Then its entirely their own choice, obviously you explain why You do this as politely as you possibly can

That’s also comes with experience unfortunately especially when they choose not to listen which all of us do from time to time I’m not free of this either but that’s also a good approach to this challenge and this too works because after they have its all apologies and lets all be friends

Also normal this !! They always know better never ever listen or take on board what you are saying Human nature this !!

That’s a fair assumption of this and that’s good advice to you as a person and its shows that I respect your views and so you should mine

Next I thought you start with why your companies are not co operating and I think we are entitled to explanations from some of you and you might like to answer to the royal family re this as well you see with a please explain why , " For example , Oh dear , Motorola , Samsung , Nec , lets see who else ? Robinsons radio, Pioneer who are also not co operating with British subjects and then you see I thought you might also like to explain why , correct !! You are also not co operating with your so called allies and I thought this might be very interesting for some of your officers , as well as your communications companies but I’m positively convinced you can explain all of this cant you Inclusive the recent wave of violence Woolwich etc etc " ought to be very interesting !! " And then on a far more positive note If you live in Britain which as far as I can see you operate from and run business from

What exactly is your problem and why is it that you all seem to think that you can do this to persons personified and I also thought you might explain all of this so called highly sensitive data when you all live and work in the same country because this is no big secret anymore

Would you care to take the stand and tell us all about this ?? And then you can also tell us why you are continually trying to set some of us up hmmm ought to be interesting as well !! And why you think you can go around thunmp many people when you are actually no better yourselves inclusing your bussineses

Must be for some obscure reason !!


Whats up have we got a slight problem ?? Well you wouldn’t believe us would you ?? Gone a bit to far have we ??


After all we are all lyers aren’t we hmmm Interesting and then what i thought you might like to do is please explain why the rest of your businesses are closing and why we have such a problem with this as well and also why there is so much nemployment despite your governments statistics , house prices , rents , rates , and the general state of business in the Uk in general

I thought you might like to explain all of this , pub closures , , shutting peoples electric , gas off etc

I’m ever so looking forward to all of this plus what you have been up too the poor despicable wages , refusing to pay people on time that you have been paying for excessive hours and the general manor in which you have been treating this country and why you also decided to shaft the whole country

Good , Excellent news , Don’t let me stop you

feel free as they say !!

Off you go then Ill let you start all of this off all of this off inclusive the bad references behind peoples backs that you thought we didn’t know about and the rest of this story We will undoubtedly have all of this on the table now What do you say to that one ??

I think excellent idea that’s what I think about all of this story inclusive the hospital closures

The number of people that need mental; health care and where you have sold off the hospitals converting these into private accommodation and left these people on the streets of London etc and also why there are so many people that are now being attacked by people with severe mental health problems as well

I think that’s fair don’t you ?? I definatly do I do So well have some explanstions or Im going to ensure they shut you down untill we do get explanations inclusive the massive housing shortage in the Uk which also needent exist

Lets have it !!

Hey There!

I believe this type of circuit works very much like a simple NAND Gate with multiple outputs. I would recommend you guys to search it out, It's actually one of the basics in Electronics. Considering that your friend is already at University, he should pretty much know about Logic Gates and other stuff.

Another thing, what your doing is really nice (helping your friend) however Assignments and Projects are really part of being a student, there are no short-cuts and yes there would really be a lot of other subjects and stuff but this is where "time management" comes into the picture for him. If your friend is having a hard time with basics like this, then higher subjects would pretty much be like way way out there for him.

Nand gate is one answer I agree but there is one problem.
GATES I remember them by the help of internet resource. I did it in my diploma also in my 4th semester

Problem :

In NAND gate if both the input goes down then also buzzer and Led will work. Led and buzzer should work only when one input is dead and other is active. but in NAND gate circuit this is not the case. I think you can help and near to problem. Please give correct solution. Thanks for small help. Atleast I am in position to say something to him.

Please help more.

I have to say you are one of the best help across all over the internet I posted since last night. Thanks

In that case I think the XOR (Exclusive OR) Gate should do the trick... it only conducts when either 1 of the 2 inputs is off.

Thanks its done we can close this thread.