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Discussion Starter · #1 ·
What are folks using for a non-usb power supply for their Arduino? I am using a 9VDC wall wort and it is causing unstable activity with my project. USB filtered power is fine. Thanx!
 

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Is it regulated power supply? Put a meter to it, see it you are having over voltage. The on-board regulator will regulate 7-12 volts down to the 5 volts operating, anything more can cause problems.

What type of Arduino? Uno? Are you powering it thru the jack?
 

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I am using a 9V wall wart for my arduino micro. I made sure it was not supplying over 10V though. Some that I picked up at the flea market / goodwill were putting out as much as 18V when they were supposed to be either 9 or 12 V supplies.

If your PS voltage is within range then check for loose connections. The only intermittent issues from my controller / relay set up I ever had was related to a poor shared ground connection and a loose connection on the jumper that is on the relay board.
 

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Discussion Starter · #7 ·
I'm using a Uno. Wall wort is 9v/1A, measures 9.4v with no load. Feed in through the jack. When I use the USB to power, all is well and it's very stable. I've tried a 12v wall wort and it goes crazy...so I'm thinking its the power supplies...probably not filtered. What wall wort brand and output have folks had good luck with? BTW, I'm powering an 8-relay module.
 

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I am using a 9V wall wart for my arduino micro. I made sure it was not supplying over 10V though. Some that I picked up at the flea market / goodwill were putting out as much as 18V when they were supposed to be either 9 or 12 V supplies.
It's important to check any power supply before using, especially flea market/garage sales etc. You can't rely on the stated output which will not be correct if the power supply isn't regulated or switching. A non-regulated supply will ALWAYS output higher voltage until the load equals the rated amperage. If the load exceeds the rated amperage, the voltage will drop below the stated number. For the most part, it's best to use regulated or switching power supplies.
 

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I'm using a Uno. Wall wort is 9v/1A, measures 9.4v with no load. Feed in through the jack. When I use the USB to power, all is well and it's very stable. I've tried a 12v wall wort and it goes crazy...so I'm thinking its the power supplies...probably not filtered. What wall wort brand and output have folks had good luck with? BTW, I'm powering an 8-relay module.
I doubt it's a filtering issue. I assume your relay board is 5V? Are you powering the relay board from the Arduino? If so, that could be the issue, the Arduino voltage regulator is likely cutting out from the load. Try powering the relay board with a separate power supply and see if the problem goes away. When using 2 power supplies, you may need to connect a common GND between the relay board and the Arduino.
 

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Any update?? I am thinking it is the ground reference between the relays and the arduino. Since I also use a home grown controller I am interested in the fix to keep in my troubleshooting memory bank in case I run into an issue in the future.
 

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Yeah, I'm wondering on an update too. I would tend to doubt that it's any wiring issue because he said everything works fine when powered from the USB.
 

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Drawing too much current from the 5V rail is a common problem. When it's running from the USB input it's all good, but on the DC input the regulator has to try and supply it (and often can't).
 
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