My first project - some guidance needed please :P

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oren_partesana:
Hello, I've decided to try and make a project.
It is to make a device that pushes my light switch to turn it on and off, and to control that device using my android phone.
What I have in mind is using a servo motor for the pushing, a bluetooth module for wireless control and AA batteries for the power supply.
This is rather ambitious but I like challenges :wink:

How many projects have you completed up to now? This is much too complex for a beginner.

Also using a servo to control a light switch is a strange idea. What kind of switch is it? A wall switch or is it a switch on the cable for a plug-in lamp? You should be using a relay to switch the mains power. However, you should not be doing anything with mains power unless you are experienced, otherwise you could injure yourself or burn your house down.

oren_partesana:
Servo motor: http://www.amazon.com/HOSSEN®-10pcs-TowerPro-Torgue-Heicopter/dp/B00CCZDJX6/ref=sr_1_7?ie=UTF8&qid=1433077363&sr=8-7&keywords=servo+motor

Did you realise that listing is for 10 servo motors?

oren_partesana:
Bluetooth module: http://www.amazon.com/KEDSUM®-Arduino-Wireless-Bluetooth-Transceiver/dp/B0093XAV4U/ref=sr_1_1?ie=UTF8&qid=1433080227&sr=8-1&keywords=btm222

Looks OK. What app do you plan to run on your phone? Will you create a new app, and if so, how?

oren_partesana:
Battery holder: http://www.amazon.com/URBEST®Two-Leads-Black-Battery-Holder/dp/B00OKK5Z9M/ref=sr_1_2?s=electronics&ie=UTF8&qid=1433077802&sr=1-2&keywords=3+aa+battery+holder

That should be OK, but you must power the Arduino through its Vin pin, not the barrel jack. You will also need a 3.3V supply for the bluetooth module. The Ardunino may provide that. Running on batteries like this, the whole circuit will run for 1 to 2 days before the batteries need replacing, I would imagine.

oren_partesana:
Arduino board: http://www.amazon.com/Arduino-Board-ATmega328P-Microcontroller-ATmega16U2/dp/B006H06TVG/ref=sr_1_4?ie=UTF8&qid=1433076745&sr=8-4&keywords=arduino

That should be OK, but your bluetooth module is not a sheild, so you will need to connect it via a breadboard, at least for prototyping. In which case you could also consider a Nano 3. They are smaller, but similar in capability, and can be plugged directly into a breadboard, so less messy wires.

oren_partesana:
The thing I'm most worried about is power. I'm not really sure what and how many resistors I should use and where to place them, and whether the power supply will be enough for the bluetooth and servo.

So what I'm asking is, can someone explain the basics of using resistors and managing voltage and current, and help me with my specific case? I've read a lot but I can't seem to figure out how to apply it to my project. Also, is 4.5v from the 3 AA batteries good enough for this project?

One problem may be that when the servo operates, it may draw so much current that the battery voltage may drop and cause the Arduino to reset. Many people advise separate batteries for motors and Arduino.

I can't see any need for resistors with your current components.

Paul

oren_partesana:
It is to make a device that pushes my light switch to turn it on and off, and to control that device using my android phone.
What I have in mind is using a servo motor for the pushing, a bluetooth module for wireless control and AA batteries for the power supply.
This is rather ambitious but I like challenges :wink:

And you also like to change/charge the batteries in your light switch as often as you charge your android phone?

You may be interested in this RemoteXY Thread which uses an Android phone for control.

...R

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You need to work on each part of your project individually, then put it all together. Like get a servo and develop how you will control and power it.

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I'd recommend to you to begin with babysteps before doing the whole project, because you are beginner.

Like this,

  1. Learn how to move a servo with Arduino
  2. Learn how to communicate to Arduino with bluetooth
  3. Move a servo through bluetooth (steps 1 and 2 together)
  4. How to set up a barebone Arduino with battery.
  5. Steps 3 and 4 together.

I agree 100% with @mart256

But that would not prevent you from buying a bunch of stuff up-front, provided you are aware that you may discover that some of the stuff is not ideal, or that you may think of a better way of doing things as your experience grows.

...R

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I see. I was actually planning on doing it in increments but I wanted to know it's actually doable and reasonable before starting.

The idea is to work out as many issues as you can using just the software and debugging techniques before actually purchasing any hardware.