PCB layout for This Security Alarm....??

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They are different in sense, the earth is a connection to ground at user premises, while neutral is grounded by the public mains distribution system at the distribution transformer.
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In the US, the earth and neutral are bonded (connected) at the service entrance.

In my computer room, for example, the DC resistance from neutral to earth measures about 0.2 ohms (probably the probes).
 
mneary said:
In the US, the earth and neutral are bonded (connected) at the service entrance.

In my computer room, for example, the DC resistance from neutral to earth measures about 0.2 ohms (probably the probes).
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You are right. In India too, where the user has a in built 1100/440 3 Phase transformer at his residence, (or let the case of multistory apartments), this procedure is followed in the compound, near the Transformer.

Now in case of independent residences, the public distribution system has a common transformer. Here also, if the house is close to the transformer, what you said is applicable. many places the 230V/50Hz, single or 3 phase, is distributed for over an area. At times the distance is around 3 furlongs (round 600Mtrs). In such cases, the IR loss on the neutral would be around few volts.the user compound would have a protective ground and it is connected to the ground pin but not to neutral. As, such connection would imply a short circuit and longitudinal currents would flow, across neutral wire.

Such cases and in the event of accidental neutral breaks, this circuit under concern is likely to damage and cause personal hazard even.
 
ericgibbs said:
hi Sarma,
I am doing just that, ie; Desktop, MSWord.... the unzipper reports 1 failed open. The doc file is empty.!

Any chance you could post the extracted files from your end, I would like to see them.
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Here it is. For ease, I have pasted them on MS Paint and saved as .png file.
 
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hi shubhamjain_007
I agree dont use this circuit.!

For future reference I have attached a layout for the 555 astable circuit.
The wide track is 40thou wide and the narrow track 20thou.

All pad holes 1mm in diameter, with a 60thou outside dia.

They idea would have been to copy and paste to single circuit on the pcb, this drawing, side by side 3 times, OK.

Do you follow this.?
 
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Thanks to everyone who helped me even after my misbehave ,, i really appologise for that ,, actually it was all because of frustration ,, but i must say that all the respected members here are doing a grr8 work ,, this forum really rocks ,,

and yes everyone of you might be eager to know whether my PCB design is completed or not ,, so let me tell eveyone that after all your warnings like
FIRE , INJURY , DEATH due to vulnerabilities of the circuit ,, i have finally given up the idea to make that myself ,, i have contacted a Electronics shop here locally in my city ,, who would rather make it ( if it is possible) & test it for few US $ ,,

just realized that programming in Perl ,, python ,, java (what i do basically ) is much easier comparing to electronics ,, so better i do that only ,, atleast it wont cause FIRE ,, INJURY ,, DEATH ,,

once again Thanks all of you ,, ..... cheers!!!!!
 
blueroomelectronics said:
What do you need it for? It's a lousy design why not just buy an alarm system?
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Perhaps the person has to make a project as part of education practicing EDA software. So he need not design a circuit but be able to draw a PCB layout, may be. many people who come with say, assemble FM radio, voltage stabilizer, UPS etc are all for practice and educational need, never for actual use. this junk of project stuff will probably made over to the college where they study.

It is lousy and the EFY lab has indicated at the bottom, that they found 9V (thought it to be DC and provided a zenor, over there)between Gnd and Neutral wires. This observation is case specific and they should have rejected the article on generalisation that it is risky.
 
Rami00972 said:
i think you give him the fish
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You will perhaps withdraw your comments, as Ericgibbs is not that junior that he can't fish. perhaps being a person with 36 posts, you alo need to look at the profile of other members. Sorry for my comment, Rami.
 
mvs sarma said:
You will perhaps withdraw your comments, as Ericgibbs is not that junior that he can't fish. perhaps being a person with 36 posts, you alo need to look at the profile of other members. Sorry for my comment, Rami.
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hey sarma i have a feeling that Rami was not pointing Ericgibbs ,, i think he didn't read all the post and thought that you made a PCB layout for me ,, so he meant that you have given fish to me..........
 
shubhamjain_007 said:
hey sarma i have a feeling that Rami was not pointing Ericgibbs ,, i think he didn't read all the post and thought that you made a PCB layout for me ,, so he meant that you have given fish to me..........
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Perhaps. But when trying to pass a comment that could become controversial, i thought one has to study thoroughly, while criticizing a circuit or ohms law, we can always say that "oops"-- i missed it-- or I get corrected thanks to ..."
this method also won't go for long. the very next moment onwards I have to be cautious. I was only suggesting, so that we can have a smooth sail and still get the help from the forum.
 
shubhamjain_007 said:
hey sarma i have a feeling that Rami was not pointing Ericgibbs ,, i think he didn't read all the post and thought that you made a PCB layout for me ,, so he meant that you have given fish to me..........
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hi,
Its important to note that I did not do the full pcb layout, which would have been a big fish, but just a fragment covering the 555 section.

I would expect that shubhamjain now would be able to complete the full pcb layout himself, now that he has been pointed in the right direction.

So it might be said, I gave shubhamjain the hook so that he could catch the fish himself...

Once a fisherman has a hook, he has the means to catch more fish..

Regards
 

I think Jain has already indicated to leave off this project and be after software like Java,--- , in one of his replies. We may well keep off this post, as stopped by the OP himself, and go ahead.
 
mvs sarma said:
I think Jain has already indicated to leave off this project and be after software like Java,--- , in one of his replies. We may well keep off this post, as stopped by the OP himself, and go ahead.
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hi Sarma,

I agree.

The point I was making to Rami is, that its OK to help an OP to get started, but not to do all the work for him.

Have a nice day.

Regards
 
mvs sarma said:
You will perhaps withdraw your comments, as Ericgibbs is not that junior that he can't fish. perhaps being a person with 36 posts, you alo need to look at the profile of other members. Sorry for my comment, Rami.
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Man.... i learned PCB lay out and schematic on Expresspcb just in 30 minutes its not that difficult to learn some thing..... then i teched it and in a robotic course so i have some experience.. but in this forum may be the language" English" could not help me to make more pasts.
but you should know not any one have a gray hair is an old man.
 
I do honor you and your knowledge Rami jee. I do hope to see more posts and your valuable contribution, one such appears a possible competition for designs. A really good angle to think.
 
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hey Mr. Sarma i need ur help , pls pls explain in detail ur second point --> "As already pointed out, the secondary of the transformer should have been with centre tap and with connection to C1 -ve side."

what does it mean , how can i get rid of this problem , becoz the person who is making this for me was also a bit confused , he was telling something like he is confused about negative line , , i didnt get him properly , so was he complaining about same prob. Tht you were telling ? Pls help
 
try to see the single winding secondary of the mains transformer(say 0-12V AC). To get DC from this you need a bridge rectifier. But if you have a centre tapped Secondary like 12-0-12 V AC then this configuration called full wave rectifier would work. In a full wave rectifier you have to use the centre tap as common negative. Perhaps it is more clear now. you can find then in all electrical and electronics fundamental books. otherwise google for full wave and Bridge rectifier configurations, and you will get.

plase see if you have a single winding secondary, then use two more diodes in the reverse and common their anodes and connect to common negative and it would solve your issue
I have attached modified diagran only for bridge rectifier part. the risk of supply voltage on neutral wire still remains. I don't understand how EFY could call it wireless....?
 
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