I am a beginner when it comes to Arduino and electronics, but I've built a few projects on an Uno and am having fun with it.
Right now I have a project which is both an Altimeter as well as a Servo Parachute Release for my water rockets.
I think the Uno solution is working just fine and I am powering it with a 9v battery via the simple battery connector.
I want to look at moving to using a Nano to streamline the design and I am getting stuck at the powering of the Nano. I get that I need to provide power either via the mini USB or directly to the board in the form of battery power but all my searches lead me to project about recharging batteries and things that seem to complicate my simple needs.
Is there a simple tutorial that show how you can power a Nano with +/- 5v of power so that it can run a Servo and a BMP180 or BMP280 - the BMPs only need 3.3v. I've seen a few diagrams that show powering the servo with its own battery and the Nano with another ?
What I'd really love to see is what parts are needed as well as where the connection of these parts hook into the Nano. I'm fine to do a little soldering if that is needed. I have a couple of 9v battery connectors for the Uno - can I just clip off the connector and solder the red and black wires to +/gnd on the Nano ?
I looked up the specs on the Nano and it can be powered by placing 7-12 volts on the "Vin" pin and Ground on the "G" pin. Your 9V battery certainly meets this expectation.
Below is a picture of how you can power the board, as well as a snippet from the specifications page. All you would have to do is cut the small barrel from the end of the 9V battery snap so that the two wires are showing.
I think I will go for a AA/AAA battery holder - something like the attached image.
It's just a little bulky but I'm not yet at the point of optimization yet, still just trying to get a functional solution. Going from an Uno to a Nano is already a big step in streamlining.
If you only use 3 AAs in that holder, you will need a "dummy" battery to complete the circuit, I use a piece of 1/2 inch copper rod cut to the length of a AA and wrapped with tape, aluminum would probably work as well.
For my purposes I only need very short lived power - like less than a minute or two.
Its to power a parachute deployment mechanism / altimeter for a water rocket which end up flying for relatively short periods of time.
I was able to clip the plug off the 9v battery connector and i then soldered jumper on to the ends so I could easily plug them into a breadboard for testing and it works perfectly at least for now.
I'm still in the prototyping / testing stage of my project
The only thing I like about the 9v compared to 4 AA batteries is the weight !! Quite a noticeable difference. So in this case the most optimal solution might be something else but for now a 9v looks like it will do the trick.
Already going from an Uno to a Nano is a huge saving in terms of size and weight for my rocket payload.
If you just make an Atmega 328 on a piece of stripboard and use its internal 8MHz clock you can run off two alkaline cells (3v). I suspect a paid of AAA cells would power it for a long time.
And you can get some very small LiPo cells (3.7v) that could also power it and should be even lighter.
Indeed a 3v coin cell may be sufficient.
For even more weight reduction use an Attiny.
And I have built a few projects without any PCB, which would reduce the weight further. In my case I omitted the PCB to save space rather then weight.
