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Power Failure Alarm Circuit..Help Needed!

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panther1

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I am building a power failure alarm circuit as a project for College on a breadboard.

The Circuit Diagram, that i am using is as follows

**broken link removed**

I think there is something wrong with circuit, I have re-wired it a dozen times and it isn't working, the resistors are just preventing the flow of current, maybe the resistance is too high? Could it be?

what should i do? please help...I am new to circuits and this one is just killing me...
 
And you might as well get used to looking at and understanding the internal block diagrams of ICs. For a simple one try a GFCI diagram, whereas a schematic for a 741 opamp is pretty involved.
 
I know the structure of 555 timer IC and how it works..I just need help in wiring the circuit on bread board..
 
I have re-wired it a dozen times

this one is just killing me
So it's likely you have followed the diagram correctly.
From my own experience in situations like this, I think you are assuming something that is not true and finding what that is can be real work.

Of the two possibilities of a bad diagram and/or a bad 555, and knowing the guts of the 555, which is more likely?

Regardless of what's in a 555, posting the voltage levels will give you more clues and we can then all interpret them. A scope will tell you even more.

This situation shouldn't really be about getting the circuit to work, it should be about having a logical sequence to find the problem. Having a troubleshooting strategy will serve you better in the long run no matter what test instruments you have.

Calm seas will never a sailor make.
 
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I know the structure of 555 timer IC and how it works..I just need help in wiring the circuit on bread board..

That response is insufficient to the question asked.

Regardless of what's in a 555, posting the voltage levels will give you more clues and we can then all interpret them. A scope will tell you even more.

This situation shouldn't really be about getting the circuit to work, it should be about having a logical sequence to find the problem. Having a troubleshooting strategy will serve you better in the long run no matter what test instruments you have.

Look at that schematic. It will not work.

The six step troubleshooting proceedure, or any troubleshooting strategy begins with knowledge. The OPs response to Nigel's question clearly indicateds the OP is lacking the knowledge to know why that circuit isn't working. Was this a circuit the OP found on the internet or did the they design it.

The OP did not say if the power being monitored was AC or DC. They did not indicate whether or not the alarm was automatically resettable or manually resetable or even remotely resetable. The diagram is lacking some decoupling capacitors to ensure there is no power dips from whatever source they are using to power the 555.

If they were monitoring AC power, how many AC cycles of the 60 Hz or 50 Hz source will the alarm accept as normal (non-alarm) and how many must trigger the alarm.

These are just the questions I'd have on this project. A simple manually resettable alarm consist of a push button switch, a relay with at least two sets of contacts, and some type of alarm (audio or visual). One set NO contacts will parallel the push button switch to "latch" the relay in the energized position. When the power fails, the NC contacts will energize the alarm and remain energized until manually reset.

On edit ...

Norator, you asked for the oscilloscope display ... well, I attached one for you arramged by pin number.
 

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