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Topic: arduino controller circuit (Read 1 time) previous topic - next topic

zehneinsvierzehn

well, concerning the piezo, i did some huge mistake...
the piezo doesnt need to get the 5v, i want it to work as a sensor, kind of as a knock sensor
think i'm just gonna use it like this: http://www.arduino.cc/en/Tutorial/Knock
---> but there's the diode missing, could you tell me where exactly to put it then?
(if found this: http://www.arduino-tutorial.de/wp-content/uploads/2010/08/piezo.jpg - i'm talking about the right piezo, it's confusing me, i don't get the connections...)

---> if i lowered the resistor values of the ones before the LEDs to raise the current to, lets say, 20mA, wouldn't i draw 80mA from the arduino as i do this 4 times?

---> could anyone answer my switch-questions i asked in the previous post here? i'm still a bit confused about that

is there anything that speaks against using body contacts instead of the piezo for the analog input A5?
what i mean is:    5v --------thumbtack             thumbtack-------A5-----1k-resistor----GND
so that if you touch both thumbtacks, you have a voltage at A5, with your skin working as a resistor. people use that in diy circuit bending toy hack actions a lot and i wondered if i could use this to control software stuff.
---> is it dangerous for me - arduino will still be plugged into usb while in use? is it dangerous for the arduino? is it right to connect it like this?

thank you

Grumpy_Mike

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i'm talking about the right piezo, it's confusing me, i don't get the connections.

That is because there is a wire missing and one in the wrong place. The wire missing is to connect the ground to the diode cathode and the 1M and the piezo. The wire in the wrong place is the short circuit across the diode and 1M.

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lets say, 20mA, wouldn't i draw 80mA from the arduino as i do this 4 times?

Yes, the arduino can source up to 200mA of current not more than 40mA from each single output so 80mA is well within this.
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5v --------thumbtack             thumbtack-------A5-----1k-resistor----GND

You are exposing the arduino input directly to potentially lethal static. You might want to put a 100R in series with the input and put a 5V1 zenner across the input to protect it. It might work well enough but you will probably have to lick your fingers first. There is no danger to you doing this.

PaulS

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you will probably have to lick your fingers first. There is no danger to you doing this.

Depends what you have on your fingers...

Grumpy_Mike


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