Will a phone charger be hot when supplying power to an Arduino?

Currently planning on using a phone charger to supply power for my project. I know phone chargers may be hot when charging phones, but I am not sure if it will be hot when powering an Arduino. The heat will be a hazard in my project. Should I use a phone charger or should I use another way to power my Arduino Nano?

Phone chargers are great. If it gets hot charging a phone, that may be something of a concern about a particular brand - or "no-brand". :astonished:

The Arduino itself uses a trivial amount of power; what else are you proposing to connect?

I will be using the Arduino to monitor the Temperature and Humidity. Will be connecting 12 DHT 22 sensors, a SD card and a LCD screen. Will maybe connect it to a ESP8266 in the future

Any phone charger should be enough for Arduino itself since it should provide 0.5A at least, but if you want use some additional HW, you should check the need of current.

Old, by which I mean ones from at least 10 or maybe 15 years ago, phone chargers had a simple mains frequency transformer in them, they got hot even with no load. Modern chargers have a switch mode power supply, which still contain a transformer but a tiny high frequency one, don't get hot. The old ones are easy to spot because they are significantly heavier than the modern ones.

However, all electronics produce some heat, even if it's not enough to notice. You need to stop thinking in terms of whether or not it gets hot and start thinking in terms of whether the small amount of heat the power supply inevitably produces is acceptable or not.

PerryBebbington:
Old, by which I mean ones from at least 10 or maybe 15 years ago, phone chargers had a simple mains frequency transformer in them, they got hot even with no load. Modern chargers have a switch mode power supply, which still contain a transformer but a tiny high frequency one, don't get hot. The old ones are easy to spot because they are significantly heavier than the modern ones.

OK, let's hope it is understood that when referring to "phone chargers", we are talking exclusively of those with a USB connector and providing fully regulated 5 V, not some random charger for an ancient Nokia. :grinning:

Essentially, all USB-based chargers are switchmode.

nathannyc:
Will maybe connect it to a ESP8266 in the future

No point connecting an Arduino to an ESP8266. The ESP simply replaces the Arduino. If you propose this, best get a WeMOS D1 Mini and work with it to start with.

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Paul__B:
No point connecting an Arduino to an ESP8266. The ESP simply replaces the Arduino. If you propose this, best get a WeMOS D1 Mini and work with it to start with.

In general I have to agree, but OP has one of the few exceptions:

nathannyc:
I will be using the Arduino to monitor the Temperature and Humidity. Will be connecting 12 DHT 22 sensors, a SD card and a LCD screen. Will maybe connect it to a ESP8266 in the future

The 12 DHT sensors mean 12 individual pins, and port extenders are out. That also means the ESP8266 can't do this. The ESP32 does have the required number of I/O pins.

wvmarle:
The 12 DHT sensors mean 12 individual pins, and port extenders are out.

74HC4067. :sunglasses:

OK.

So that's 5 for the 74HC4067, two for the I2C, and four for SPI (including the CS pin) for a grand total of 11 I/O.That should be possible indeed, but unless the display is run off the SPI bus on GPIO6-11 there are no pins left at all, even no Serial debugging possible. This overloading of the SPI is possible on the NodeMCU (though no luck with it for me so far), not the WeMOS as the required pins are not broken out.

Connect the 74HC4067 four select pins to the data pins on the display adapter. :sunglasses:

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