Hello I am new to these forums, and am in the stages of designing a circuit for my school gcse electronics project. I am trying to make a safe alarm which is triggered by a passive infra-red sensor, or possibly a micro switch. But I would like this alarm to be fully automated for the owner, and so once they have calibrated when working hours are finished (eg 5pm) and when they start (eg 7am) the alarm will be activated. This alarm when triggered will then spray a fine mist of smart water on the user and the items stole aswell as a siren and flashing lights (astable).

So far I have discovered that a 555 timer will not be accurate enough as it will be loosing upto 15 minutes or more day. So, so far I have have investigated using a 4060 counter, and a 4040 ripple counter in conjunction with a quartz crystal. So I was just wondering if anyone could shed some light on the subject of how to make the timer circuit which can then be used in conjunction with an AND gate. Once of the inputs being the users key card to activate the alarm, the second being during the designated time period.

Anyway thanks for the help guys.... hope I you guys can because I am having problems. Also i would like to avoid using a PIC chip unless it is absolutely necissary.

 

Is there any particular reason why you do not want to use a PIC? i.e. no programmer, no software developing software or lack of experience?

Many a circuit can be found using PIC's for the desired application and I think that the timer resolution would be much greater than using discrete components.

BTW. Can you please indicate where you are from? It can make helping you much easier.

 

im from england, i thought from the GCSE bit most people would work that out. Although in south africa its proberly not a common to hear about. Anyway the school has a PIC controller etc, and I was just talking more to my teacher and he said that it might be the route to go down. But i need to make a circuit which is sophisticated enough to get marks for A and A*. Anyway the program at school is PicAxe, if someone could find me a flow chart for a 24 hour clock on there website (google it) that would be great.

Thanks again guys I can see this forum is going to be of great help

 

One way would be to use an LED clock chip such as the LM8560. You'd have to figure out which digit outputs you'd need to look at for controlling the alarm. You'd probably need a display for setting the clock though.

Or you could just buy an LED alarm clock and use the parts in your project.

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Carl

 

I really need to avoid using parts if i can, it gets marked de-ducted. Anyway could someone help me with PIC programming uses flow charts

 

You should be able to figure out a flowchart on your own. That is what the project is about. To show what you know. Not what you can get us to do for you.

There are numerous examples of digital clocks using PIC on the web. I think Microchip may have an appnote on the subject. Once you get the clock working the rest is easy.

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search engine for electronic parts
Junebug USB PIC programmer kit., USB Bit Wacker, 3v0's Homepage
The 15 Minute Printed Circuit Board! (+drill time)

 

no i dont want you guys to do it for me, just was looking for a point in the right direction in PIC processing. What is microchip? A peice of programming software for PICs? SImilar to PicAxe?

 

MicroChip are the company who make PIC's. A PICAXE is just a PIC pre-programmed with a BASIC interpreter, so it's limited and slow - but easy to use and cheap.

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PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

Welcome to the forum!

If you google "microchip pic", all will become clear.

You still haven't filled in your location in your User CP. You can't expect international readers to guess where you are from based on locally-used terms buried in your posts. I happen to know what GCSE means, but I suspect the term would draw a blank stare from the vast majority of non-English people.


Torben

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Curiosity was framed. Ignorance killed the cat.

 

Some background would help.

Can you program in C, Basic, or Assembler ?

What experiance do you have with microcontrollers, you mentioned PICAXE, have you used it ?

How long do you have to do the project ?

__________________
search engine for electronic parts
Junebug USB PIC programmer kit., USB Bit Wacker, 3v0's Homepage
The 15 Minute Printed Circuit Board! (+drill time)

 

well the picaxe program uses BASIC. But would you say pic chip is the way to go?

 

Do you definitely need this 'out of hours' function? Using a PIC is probably way out of the specifications of GCSE projects. Indeed, microcontrollers are only just covered in A level. When I did mine, albeit many years back, I used two 555 timers for a similar project.

In my circuit I had one 555 as an astable to drive two flashing LEDs which indicated the alarm was 'armed'. I used another to drive a speaker to generate the 'alarm' noise when a reed switch connection was broken. The on/off for the whole circuit was a key switch from Maplin.

For other posters.. GCSE only just covers the basics of a 555 timer circuit. There is a lot of emphasis on other aspects, e.g. explaining in the report how an R/C circuit works and making a pretty 'product' for the customer. You can get almost 100% from two 555 timer circuits and a good report

Can you think of any other functions that you might like to add which are simpler than relying on time of day? Perhaps we could help with that instead.

 

And which country is GCSE?

 

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Bill
Smart Kits build Smart People
http://www.blueroomelectronics.com

 

Um, Never mind Blueroom beat me to the punch.