Help reset/regulate piezo (newbie)

Other Hardware Sensors
1

Hi, i'm trying to build a simple, cheap scooter alarm using arduino and (for now) a simple piezo vibration sensor (I have this: Piezo ). I have connected it like in this tutorial: http://arduino.cc/en/Tutorial/Knock
I've found a great place under the seat, fixed to a metal plating to put it and act both as a force (push, when you sit on it) and a vibration sensor (when someone would try to steal it). My problem is that once it starts vibrating, it has a very long cooldown period, i mean it would take at least 4-5 minutes before it's output via serial drops below my treshold.
My problem is that once triggered i want to have a way to stop (i.e. turn of alarm, for example if wrongfully triggered by a dog or someone who hit it by mistake) and then start again, such as a reset.
Is there any way of reducing this cooldown period?

Bear in mind i'm pretty new at electronics :~

Thanks in advance :slight_smile:

2

Try grounding A1 and taking a reading from that when you want to reset. That will discharge the input capacitor.

If that doesn't do the trick, a lower resistance value might help.

3

i got my ardu 2 days ago but id say try something like this:

if (sensorReading >= threshold) {
ledState = !ledState;

"if blabla switch high
ledState = !ledState;
else"

digitalWrite(ledPin, ledState);
Serial.println("Knock!");

you can find that button stuff in examples, in my imagination you would have to wait to hit the switch again till ur threshold is again low enough

4

johnwasser:
Try grounding A1 and taking a reading from that when you want to reset. That will discharge the input capacitor.

If that doesn't do the trick, a lower resistance value might help.

Yes, a 470kOhm resistance seems to behave better. I think you meant to take the reading from A0 (as that's to what the piezo is connected)!?

Thanks #johnwasser

5

yonutz33:

johnwasser:
Try grounding A1 and taking a reading from that when you want to reset. That will discharge the input capacitor.

If that doesn't do the trick, a lower resistance value might help.

Yes, a 470kOhm resistance seems to behave better. I think you meant to take the reading from A0 (as that's to what the piezo is connected)!?

Thanks #johnwasser

No, I said GROUND A1 AND TAKE A READING FROM THAT (A1) TO RESET.