Power Supplies for Arduino and Sensor

Hello all.

I am using in my project an Arduino Mega and an MG-811 sensor (http://sandboxelectronics.com/store/index.php?main_page=product_info&cPath=66&products_id=197).

My issue here is that I don't want to use two power supplies. I thought I should use then either 5V AC for Arduino and then take this signal and step it up with a regulator, or use 9V AC for the sensor and step down to power the Arduino.

Do you think this is a good strategy? And also, could someone recommend a AC regulator for this project that might be suitable?

Thank you.


It appears that your sensor takes an input of 6-12V which runs the heating element. Since it can have either AC or DC, suggest you run with something in the order of 9V [u]DC[/u] which you can split out to the Mega also. The voltage regulator on the Mega will bring that down to the 5V it needs onboard and is suited to DC input voltage from 7-12V so you'll be right in the range.

Choose a regulated DC wall wart that is capable of supplying the maximum current required by both devices - I didn't see what the heater needed in the quick read through just now, but it's sure to be there. So long as your power supply is regulated it will deliver 9V (or 12 if you choose that) regardless of the demand.

Cheers ! Geoff

Given the Mega 2560 has a power jack that takes 7-12v input and regulates it down to 5v, I would say use that. If you were building a Mega clone where you were powering it yourself, then you would have to add a regulator. Depending on how much current your sensor draws, you would either hook up the VIN pin to your sensor, or split the power before it gets to the Mega.

I see that Adafruit has a 9v 1000maH regulated power supply, but I'm sure there are other suppliers as well. http://www.adafruit.com/products/63

If you have a used computer store, they might have a bin where they sell old power supplies. You would bring the Mega to make sure the plug fits (it is a fairly standard size), and check on the specs for voltage (9v) and amps (you would need to add the requirements for the sensor and Mega).

If you want a new regulator, and need it ASAP, you might check your local big box store (Best Buy, Walmart, etc.) or Radio Shack, as they might have appropriate regulators. Radio Shack has this adapter that do multiple volts (3, 4.5, 6, 7.5, 9, and 12) if you might need different voltage amounts for other sensors in the future: http://www.radioshack.com/product/index.jsp?productId=15365586&locale=en_US

If you don't want to do the wiring for splitting the power, Adafruit and other places sell 5.5mm power splitters: http://www.adafruit.com/products/1352. You might need a female plug like: http://www.adafruit.com/products/368 to connect to the sensor, and this male plug if you want to make your own wiring: http://www.adafruit.com/products/369.