alarms (GCSE)

[Guest]

My name is James Chappell I am currently starting my major G.C.S.E course work for electronic products, the project I have chosen is to design and make an alarm system for a container. I spent a lot of time and effort researching on alarms and came up with your company.
I would be most grateful if you could send me any information you have on alarms.

[Guest]

what sort of container are you designing the alarm for?

I have designed many alarm systems in the past, and would be glad to help, just need a little more info.

[Guest]

My name is Chris and i'm doing my GCSE Technology coursework too. If its possible could you help me out. I must research 6 existing alarm products, but i have no idea where to look. Could you please e-mail me with any help. I'm making an alarm which has a loud speaker output and is triggered when a pressure pad is connected, the circuit will then stay on, because i have used a latching thyristor. The alarm is switched on and off using a key switch.

[Guest]

Hi,

What sort of alarm products are you investigating. Do you mean sensors, or just any equitment used with alarm systems?

what sort of circuit is your alarm based around?

[Guest]

i can answer that, read his post and it tells you, he is using a pressure mat (open cct) and a latching thyristor, so t looks like he is doing it the hard way

[Guest]

I would advise that you don't use latching thyristors unless your course requires that you do. I suggest that you investigate "555" monostable circuits, as these can be latched with variable time delay/reset values to filter out nuisance triggers and provide timeout resets (an important environmental noise consideration). Latching thyristors require that the latching current be reduced to below the latching threshold through the device in order to cancel/reset the latched alarm condition. Use of "555" devices in the control area, removes the need to de-latch the thyristor, which may be carrying a substantial current, and offers a more versatile control environment for the alarm device/system.

[Guest]

What you saymay is true, but i think you are overlooking one thing, our friend is only "experimenting" and what he has probably only has a thyristor and one resistor which is simple, if the truthe were known it would be a lot less hassle to go out and buy one, but that would defeat the object, LEARNING

[Guest]

well said to the writer of the previous reply!

i have a number of years experience in designing alarm systems and would be pleased to give info if needed

[Guest]

didn't the students just ask for help - not **** and one.up.manship. I thought this was meant to be a useful forum. If we have collective experience worth using lets answer the questions constructively.

[robski25]

I am currently doing a similar project for my GCSE i have been informed of 555 timers but do not really know how they work can anyone help me out?

[breezer]

unless you have to use a 555 timer i wouldn't, they are a briliant bit of kit, but trying to incororate it into an alarm is not easy.

anyway to answer your question see this

__________________
Do you like music Mr Finch?
Forum = Opinions

[deathead]

Hey, im making an alarm for A level, but I haven’t had much luck researching them. I was wondering if anyone could suggest any site’s I could look at?

[phil_ballard]

Go to www.babanibooks.com - these great little paperbacks only cost about six or seven quid and are full of circuit examples etc, all simple and well explained - for example book BP416 is on on alarm projects, and I think there's also a book on 555 timer projects too. You can get them (probably to order) from any decent bookshop or hobby/electronics shop. (No, I'm not on commission , I just have used them a lot over the years and think they're good!)

[kendor]

I presume you are learning about logic circuits and such? A Multiple input NAND gate could be used to trigger a simple 555 monostable circuit, have switches representing windows, doors, pirs etc on all the inputs and have the output of it wired to the 555's trigger pin, If you just want to output to a small buzzer then the 555 will drive it ok otherwise add a relay output to drive the alarm.

[securespark]

I made an alarm system for a tupperware container once (no, I'm NOT taking the p*ss, I'm being serious!!).

Some b*stard at school (boarding) kept nicking my stuff, so I rigged up the box to a high-decibel siren, similar to todays Clansman Inferno. Ouch. The whole school heard it and the culprit got a perforated eardrum.....

Me? I got 10,000 lines. To be done at weekends and spare time. God, they took some doing..and when I'd finished, the screw ripped them up in front of me..