Hi,
I need to use the 5v from arduino to power a bunch of sensors and I know that voltage is going to decrease over time. My question is how to minimize this drop or even better how to keep voltage fixed till batteries die completely? (I'm planning on using 6 AA)
Thank you,
Belal
6 AA alkaline batteries give 9V, so put that into a DC-DC converter or 5V regulator and the output voltage
will be 5V until the batteries are utterly flat. If the sensors only take a small current you can simply put the
9V into the power jack or Vin and use the on-board regulator - too much current would overheat this though
and cause it to shutdown.
So what sensors are you wanting to power? All 5V?
Thanks MarkT. Yes, all sensors are using 5v. The sensors I'm using are:
1- AM2315 (AM2315 - Encased I2C Temperature/Humidity Sensor : ID 1293 : $29.95 : Adafruit Industries, Unique & fun DIY electronics and kits) which uses 10 mA max current during conversion (while requesting data).
2- A thermistor.
3- An operational amplifier to amplify signal from a light sensor (0-5v) range measured with a voltage meter.
B.
Well if the total current draw is tens of milliamps you'll be fine powering them from the 5V
output. Several 100mA might be pushing it. So measure the current draws and plan accordingly.
Thanks a lot MarkT. One last question, do you think the batteries will last longer using a DC DC regulator or using the onboard regulator?
DC-DC and powering the Arduino via the 5V pin will last longer.
85-90% efficient conversion of 9V to 5V should last longer than 56% conversion (5V from 9V, with 4V x current wasted as heat).
For example, a step down regulator here
Or for even longer life, a combination step down/step up regulator which will get all the life out of your batteries
The step up/down regulator is is perfect with batteries! Thanks CrossRoads!
The question is will a DC-DC converter put too much noise on the 5V rail for your analog sensors?
Probably - go with the built-in linear regulator if you want low-noise performance from your sensors.