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hey everone....i have a circuit here....i need to know how to replace the push-to-make-switch with a tilt switch, so I could use this circuit as a bike alarm??....please help...i really need HELP!!!!!!!!
Please download the picture of the circuit attached to this message, look at the circuit and please reply me at [email protected] if you know how to solve my probelm. Thx.

post-5539-1427914195926_thumb.jpg

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Hey..sorry the circuit above is messed up...da correct circuit is attached to this message...i cant replace the push-to-make switch with a tilt switch (which basically acts like a normal switch on/off) because when the tilt switch makes contact and complets the circuit, it needs to break contact as soon as possible, so the automatic reset can happen. If the switch does not break contact, the automatc reset will not happen.
My teacher said that I have to use another 555 Timer to send a pusle to the switch to turn it off. How can i do that????.%7Boption%7D

post-5539-14279141959426_thumb.jpg

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Hi Gugh,
That's right, a 555 timer won't time-out if its pin 2 is still being triggered. So your teacher wants you to add another 555 timer to turn off the tilt switch.

Are you allowed to be a smarty-pants?
How about using the original 555 timer to turn off the tilt switch?

Just add a 1K resistor between pin 2 and the tilt switch. The tilt switch will still work like before and trigger pin 2.
Then add a diode (D1) from pin 3 (output) to pin 2. When pin 2 is triggered, pin 3 goes high and the diode also pulls pin 2 high. With pin 2 high the timer can time-out normally, even though the tilt switch might still be making contact.

I have also added a diode (D2) across the relay coil to arrest the inductive voltage spike that is caused when the relay is turned off.

post-1706-14279141960373_thumb.jpg

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hey,,,,thank you very much for da circuit...but there still is a problem...when I trigger the tilt switch, the alarm does reset itself after a while, but then it starts again for some reason? How do I solve this problem?by the way, in my circuit simulation, I am using the tilt switch as a normal on/off switch.

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Hi Gugh,
If the tilt switch is still making contact after the automatic reset has passed, then of course the 555 is triggered again. It will continue to happen until you straighten the bike!
You could turn off the alarm if you don't want it to trigger when tilted.

Maybe you want the alarm to sound only one time, but still trigger again later if the tilt switch's contacts are disconnected then re-made:
A thief looks at your bike but drops it, setting off the alarm. You ignore the alarm and the thief hears the alarm stop. So he steals the bike and the alarm doesn't go off again until he crashes the bike!
But you didn't say that.

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Sure, you can add circuitry that will turn off the alarm after it has sounded once.
But if you ignored the alarm by not straightening the bike to reset the tilt switch, the alarm is useless if you also disregard its tilt switch after the 1st alarm and turn the alarm off.

Maybe you need a circuit that will sound the alarm for a timed period only if there is a change in the status of the tilt switch:
A thief looks at your bike but drops it, setting off the alarm. You ignore the alarm and the thief hears the alarm stop. So
he picks up the bike and the alarm is set off again. He gives up.
The next thief comes to look at your bike, etc.
Maybe a thief will actually ride your bike away, setting off the alarm every time it sways.

I answered the post that you deleted and now you made another post:
A vibration sensor is just a microphone with poor sensitivity that is bolted directly to the sensed object, without the usual sound isolation material (pick-up by sound conduction, not by air), that picks-up local and very low frequency sound. Although it would need a preamplifier and filter, its operation would be exactly the same as a tilt switch that is sensed for a change in its status as above.

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A vibration sensor is just a microphone with poor sensitivity that is bolted directly to the sensed object, without the usual sound isolation material (pick-up by sound conduction, not by air), that picks-up local and very low frequency sound. Although it would need a preamplifier and filter, its operation would be exactly the same as a tilt switch that is sensed for a change in its status as above.

Hi Gugh,
I have never heard of a vibration switch, just a sensor as above. A sensor can be made to perform like a switch by amplifying its AC output then rectifying and filtering it.
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basically a vibration switch is like a tilt switch, it has two pins and a mercury ball. The ball sits on top of one pin, when the switch is tilted (by a very small angle), the ball makes contact with both pins, completing the circuit. I asked my teacher and said that a vibration switch does act like a push to make switch. Thanks alot for your help, your circuit helped me progess with my project. Thank you!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! :) :) :) :) ;D ;D ;D ;D!

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Guest Yevgenip

In the original circuit, don't be a smart-pants, but add another 555 timer that when triggerd, send a singal pulse to the alarm. try playing with that a bit.
I still dont understand why do you need an alarm that will go off when the bike is tillted.

Yevgeni.

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