USB power vs walwort power

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pherzmar
 
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Joined: Sun Jan 29, 2012 3:27 pm

USB power vs walwort power

Post by pherzmar »

I have written a simple script that detects a short circuit from spilled water and sounds a buzzer and lights an LED.
When the circuit is shorted it connects the 5v pin to analog input 0. There is also a 12 KiloOhms pull down resistor connected to ground to keep the unshorted circuit from floating around. It sounds the buzzer when the analog input 0 read is greater than 100.

It works fine when the arduino is powered by the USB connection but I get lots of false positives (it acts like it is shorted) when I have it powered by a 9v 1A wallwort that I bought from you.

Any ideas?

Thanks from a fan

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adafruit_support_bill
 
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Re: USB power vs walwort power

Post by adafruit_support_bill »

Are you powering it with just the 9v? Or is the USB still connected?

If you post a photo showing your setup we might be able to spot the problem.

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