Go Down

Topic: SOLVED: Problem when plugging heavy load devices on the same outlet as Arduino (Read 5 times) previous topic - next topic


Quick possibility is add large external capacitor on the 5V from the adapter. Say 4700uf at 10V or more...
Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
HOW-TO: http://ArduinoInfo.Info


Please advise which hospital you are plugging into  -  I need to stay clear !


Have you tried plugging the equipment into a different wall socket ? Maybe the "monitoring" power line (or that specific socket) can't handle the temporary load increase you have when plugging the equipment, so the voltage momentarily drops, making the usb charger drop the power to the arduino long enough to have it reset.
just my 2 cents.

Hello. We have many of the same exact devices plugged into many different wall sockets. I think what you are saying is the exact problem. It makes the voltage jump down and back up, causing the arduino to go haywire. The weird thing is that it completely messes up the instruction cycle. Im guessing even the memory containing instruction location is also getting corrupted. Its weird because i would guess the watchdog timer would still work, but it does not.


Quick possibility is add large external capacitor on the 5V from the adapter. Say 4700uf at 10V or more...

I was thinking something along the same lines. Or a recharging internal battery with enough charge to keep it going until the electricity is stable once again, so that watchdog can reset it. Or have some sort of hardware monitoring for voltage, and have it send a reset signal to the reset pin of the arduino when the voltage stops fluctuating.


So the Arduino + wifi are working when nothing else is plugged into the AC outlet, then something else gets plugged in and wifi stops functioning, correct?
Can you post a parts list? Which Wifi-shield?  (datasheets are helpful too!) and a description of how you have connected everything (schematic).

To answer your first question, that is absolutely correct. It works completely fine until there is a change on the electrical circuit. Even if the arduino loses internet connection, it re-establishes it after a third failed attempt, and reconnects. I have the same exact device running in my office 24/7 with no problems. Sometimes, the client connection fails and it is unable to make HTTP requests, but then it successfully reconnects to the network, and re-sends the failed request and gets a 200OK. Every time a request is made or the arduino is reset, it checks into our server -- marking the device as "Alive." We have only noticed the problem on some specific outlets in the hospital where we know large monitoring equipment is plugged in. Plus, like i said, these said outlets are colored red and labeled "CRITICAL", so i assume its dedicated purpose is to run these monitoring stations. Its only those outlets that we are seeing the problem on.

As for the parts list, absolutely (schematics linked). Here you go:

So you have multiple Arduinos setup with essentially the same code and the act of plugging in the monitoring equipment puts the arduino on the fritz, correct?  Or multiple devices connected to the Arduino? If it's the former, we can probably rule your code out as the direct source of the problem.

Its the former. Its the exact same hardware setup on 20 different devices with exactly the same code except for minor changes with some defined constants used for device identifiers. I believe its safe to assume that the code is not the problem.

Go Up