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School Project - Bike Alarm

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kink_rider

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Hiya, I am currently in the process of designing and building a bike alarm for my GCSE systems and control project. Basically my idea is an alarm that is triggered when a thief sits on your bike seat, I would like to build my own circuit and house it in a vacuum formed shell that slides underneath the seat rails. I am just struggling to find a suitable circuit diagram. I want the circuit to consist of a buzzer that is triggered by the compression of the foam on the seat e.g. micro switch or a reed switch and then de-activated by a key switch. I would like the buzzer to stay on for a certain time or until the circuit is turned off by a key switch and finally I would like it to be run by a 9V battery. Any help would be gratefully appreciated as the project needs to be completed by the 2/4/04. Thanks, Ollie.
 
You are a little late, since it is 3/11/04 already! A simple series circuit will work, battery, buzzer, SCR, and keyswitch. A microswitch and resistor is used to turn the SCR on, the keyswitch turns the buzzer off.
 
Russlk said:
You are a little late, since it is 3/11/04 already!

I didn't see a smilie, so presume you weren't joking :D

He doesn't mention his location (yet again!), but the fact he's doing GCSE exams points to him being in the UK.

We don't use the American method of dates (mm/dd/yyyy) we use (dd/mm/yyyy) - what's with the silly American method anyway? :lol:

BTW, is it Sweden who uses (yyyy/mm/dd), that make far more sense, you can do simple maths comparisons on the date without converting to Julian numbers.
 
Yes I do live in the UK and my project needs to be completed by the 2nd April. I think I already have the components to complete the circuit I need. I have a 555 timer which I would like to make the buzzer stay on for about 30 secs. I also have the buzzer, keyswitch, circuit board, reed switch (I think a microswitch would work better though) and a 9V battery snap. Does anybody have any circuit diagrams that would be suitable and allow the buzzer stay on for a certain time after the microswitch activates the buzzer? Further help would be greatly appreciated! Thanks, Ollie.
 
I will draw something out later, but you are a little late for it (I hope you have already done the paper based coursework to go with it)

I took my gcse in electronics in 2001/2002 and got an A* , it was a shed alarm, I am currently studying for A level systems and control, and I am building something using a PIC Microcontroller, anyway enough about me, I will do my best to remember to draw your diagram before the end of the day

Adam
 
Yes I'm a bit behind with the whole project really, but im sure I'll get it all done! Thanks a lot Adam a circuit diagram would be really brilliant, as I am hoping to complete the circuit at work tomorrow.
 
Here it is, just replace the on/off switch with a keyswitch and the push button with your micro switch (in such a way the contacts close when the bike is taken), the duration can be changed by increasing the size of the capacitor and the resistor it charges though, I belive the formula is time (s) = 1.1 * r (ohms) * c (farads)

The diagram is not the best In the world, it was drawn quickly and it shows juts a basic 555 monostable circuit, I belive this is what you are after?

Adam
 

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Thanks alot for the circuit diagram Adam, it looks like the sort of thing I need. I will have a go at completing the circuit tomorrow and let you know how I got on. Thanks, Ollie.
 
kink_rider said:
Hiya, I am currently in the process of designing and building a bike alarm for my GCSE systems and control project. Basically my idea is an alarm that is triggered when a thief sits on your bike seat, I would like to build my own circuit and house it in a vacuum formed shell that slides underneath the seat rails. I am just struggling to find a suitable circuit diagram. I want the circuit to consist of a buzzer that is triggered by the compression of the foam on the seat e.g. micro switch or a reed switch and then de-activated by a key switch. I would like the buzzer to stay on for a certain time or until the circuit is turned off by a key switch and finally I would like it to be run by a 9V battery. Any help would be gratefully appreciated as the project needs to be completed by the 2/4/04. Thanks, Ollie.
you smell you geek
 
Well

To Be fair guys lets not get into paddies here. Only people who call other people geeks have problems themselves. So guys settle down before people get angry and spill their emotions. This has helped with my gcse anyway so lets stay cool kids. :mad: Oh and some people have lives
 
To Be fair guys lets not get into paddies here. Only people who call other people geeks have problems themselves. So guys settle down before people get angry and spill their emotions. This has helped with my gcse anyway so lets stay cool kids. :mad: Oh and some people have lives

Perhaps you might try reading the date on the thread and posts? - it's rather a long time ago :D
 
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