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Topic: Internal/external sensor project - Power recommendations (Read 2154 times) previous topic - next topic

jameseyb

Jan 29, 2011, 06:41 pm Last Edit: Jan 29, 2011, 06:44 pm by jameseyb Reason: 1
So, I'm starting on my first proper project with my Arduino, nothing fancy, just a bundle of sensors that will measure temperature and humidity inside and outside the house, log them all and put them on the internet (plus notify me of when the postman comes!), and I'm having problems with the power source for it. I only have a single power socket to work with, and it is likely that the power from the board itself will not be enough to power everything.

I've been advised to use a standalone 5v power supply for the sensor packages (An old Nokia charger will do 5v/890mA, handy), but the board itself, especially with the ethernet shield and SD card will chew up a 9v PP3 in short order, so I was thinking of giving it a 12v supply from another one of the many bits of kit I have around the house. Ideally though, I'd like to use a single power supply to do both the board and the sensor package, and remembered that USB delivers both 12v and 5v through the cable on different pins.

So, would it be possible to get a charger that has a USB end on it and use it to deliver both voltages, or is that not going to happen and leave me being forced to use two sources? Alternatively can the board itself supply enough power for a DFT11 temp/humidity sensor, a PIR sensor, a Maxin temperature sensor and the Wiznet ethernet shield with SD card socket on it without cooking? Will I still have enough spare juice to power an LCD as well (16x2 or a 128x64 if I can find a decent one), or is this a something that I will have to forgoe?

Any advice welcome... I'm new to all this and the last lot of practical electronics I did was about 20 years ago at school and resulted in a low grade for the exam.

retrolefty

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and remembered that USB delivers both 12v and 5v through the cable on different pins.


Not true, a USB cable has four conductors, D+, D-, +5vdc, ground. There is a 500ma max current requirement when using USB power.

I would suggest you list all the devices, arduino and external devices and components, list their voltage requirements and current consumptions. Only then can there be a good chance of figuring out the simplest method to power the monster.  :)

Lefty

jameseyb

*grin* Thanks Lefty!

I'm building that list as we speak, so you might have to wait a few minutes.

List so far:

DHT11 Temp/Humidity sensor on breakout board
DS18B20 Temperature sensor
DS1307 RTC on a breakout board
Arduino W5100 ethernet shield
PIR sensor - Dammit, will have to see what it is.

retrolefty

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List so far:


Your partial list doesn't seem to include voltage and current requirements for each item? Also links to the items datasheet or user manual might be needed if not obvious how they work and what they require.

Lefty


jameseyb

Give me a chance... I'm at home and most of the kit is at work. I'm also a beer into my weekend, so it might take a while. 8)

retrolefty


Give me a chance... I'm at home and most of the kit is at work. I'm also a beer into my weekend, so it might take a while. 8)


LOL, don't worry I'm here all week.  XD
And like my beer also.

Lefty

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