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I know that similar threads had been answered but due to the fact that i am a beginner at electronics i would like to verify my measurements concerning about voltage total current and power consumption of my circuit.As you see i use an Atmega 328p microcontroller and some sensors such as Dht22(digital temperature-humidity),lm35(analog temperature)Soil Humidity(classic arduino analog sensor from adafruit).Below its my schema http://imgur.com/gdbhBi9 and a table of my results http://imgur.com/Zmq3ugE

1st Question:According to these measurements my calculations are right?
Total Current 26.8mA

Total Power=26.8mA * 12V=321mW

8battery pack AA Alkaline 2600mAh

Battery Lasts=2600mAh/26.8mA = 97Hours

2nd Question:Concerning efficiency will be better if i have a 9V power supply or a different perspective of my circuit and how i measure this in theory with numbers.

Any suggestions to my circuit and my measurements will be great!

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  • \$\begingroup\$ My little brother would unscrew light bulbs to save energy. those little chandelier bulbs? those he would unscrew. To save money. \$\endgroup\$ – Tim Spriggs Apr 8 '16 at 21:53
  • \$\begingroup\$ @G-V: Don't try to make any sense of the above comment. It's nonsense. \$\endgroup\$ – Transistor Apr 8 '16 at 21:58
  • \$\begingroup\$ Haha its ok.For me its about knowledge because now i am trying to learn about electronics and not just type some codes at arduino ide.However i still laugh lol. \$\endgroup\$ – G-V Apr 8 '16 at 22:08
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    \$\begingroup\$ I would like to compliment the question. Many times, beginners drop in without 10% of the thought that you put into the question. Bravo. \$\endgroup\$ – slightlynybbled Apr 9 '16 at 0:18
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I had a quick scan through your figures and they seem good.

Note that your 7805 regulator is dropping 7 V and the circuit is using 5 V. That means that 7/12 of your power is being dissipated as heat in the 7805. You can reduce this in a number of ways.

  • Reduce your battery voltage to 5 AA cells. The 7.5 V will be enough to power your circuit but you won't be able to drain your batteries as far before the voltage regulation starts to deteriorate. Your 9 V solution would be safer.
  • Use a buck-type voltage regulator. This will be much more efficient than the 7805 linear regulator and will work over a wide input range.
  • Do both the above.
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