How to power my final project

Hello, first of all I would like to give some background about myself.

I never did anything with Arduino before, this is my first project. I'm not very good at electronics, I am more software engineer.

What I am trying to do is make a TV remote controller. I already read IR codes that I need, I can transmit them, but now my project is in prototype state. (Breadboard, Arduino Uno is connected to my laptop).

Now I want to move this prototype to real remote controller. But I have no idea what can I do to power my Arduino Uno so I won't need to connect to laptop anymore. I know that I can use 1.5V batteries for this, but one question comes up in my mind:

Do my Arduino Uno will always need to be ON, for my controller to work? I mean, what I want to achieve is that my Arduino Uno would be off always, until I press the button, which transmits IR to my TV, and after that everything shuts down again. I guess this wouldn't drain my batteries that quickly, but I wonder whether this is possible? Cause now, when my Arduino is connected to laptop, even tough no program is running, my Arduino still has some lights on and etc. So it seems that Arduino always must be on power, and then when I press button it then only sends IR codes, but after that it is still on. I don't want that

Sorry if my question seems silly, but I would really appreciate any advice and explanation whether Arduino Uno is suitable for my final project.

To use IR I think there are more power saving Arduinos then UNO. However, to design Your system, using USB as pwr source, UNO is okey. Later You can use a pwr bank connected to USB connector.
Powering down after sending an IR code and starting up at next transmission is all ok.

Here is a good article on making a low power mega 328 stand alone board.

Thank you for your responses. I decided to use external power bank to power up Arduino Uno. One more question, is 5V 2A output is enough for my IR transmitter to operate? Or do I need more powerful power bank.

Probably, but that does depend on your IR transmitter, and you forgot to tell us about it.

Two lipo batteries might be a better choice. In series they are about 7.4vdc. And you need more volts going into the onboard voltage regulator or it won't work. Also the lipo is rechargeable

A 3.3V Pro Mini runs just fine on 2xAA batteries, or a single 3.7V LiPo. Maybe your IR thing can do as well?

Power banks switch themselves off after a while. Can become quite irritating: every time you want to press a button you first have to switch on the power bank.

In one of my projects I needed to consume some 20 - 40 mA to keep the pwr bank alive. For a mostly sleeping IR controller recharging the battory will be needed way to often.
A pwr bank and waisting current could be a quick and easy way to start construction but not for later use.

A 3.3v Arduino with a 3.7v battery isn't a good my opinion anyway. Depending on current draw, there could be Voltage drops that hinder the Arduino from working. And if the Arduino gets a voltage dip, it will restart and run the setup code again.
With IR, I don't see having that issue.
I like to have at least 2v more than what the regulator puts out.
The OP didn't specify what voltage the project operates at.

A 3.3V Pro Mini will run just fine on anything from about 2.3V (thereabout - the minimum for ATmega328p running at 8 MHz) up to 5V. Just don't use that regulator, it's not needed in this situation.

I think most TV remotes spend all their time in very deep sleep mode, and wake up when any button is pressed. I’m not sure the 328P is the best choice for that, but it might depend on how your buttons are set up. It might help if you could post a drawing of your circuit, particularly how the push buttons are connected to the 328. The question is whether pressing ANY of them can wake up the processor.

But in general I would urge you to invest the time to do this the right way, which is battery powered using a single lipo battery and a Pro Mini equivalent. You can get a super-cheap USB lipo charging module and a single lipo battery, and you won’t need a voltage regulator, and you can probalby run it for months on a single charge.

You will also need to remove, or cut traces to, any LED that lights up when the processor is sleeping. Building your own Arduino may actually be the best idea - for example, even an 8 MHz crystal may be more than you need.

Of course you can settle for the high-powered way, but I think you will learn a lot if you make it “elegant”.

Also, you may find these useful when you need to move it off the breadoard, but don’t want to have a board made:

I do not have a schema with official annotations. But I can show you an image of breadboard. (I attached photograph)

Sorry, by saying IR transmitter I meant IR LED, now I know that they are two different things.

My remote controller would have only one button which will imitate a sequence of different button presses on TV. It is meant for my grandmother, who is too old to remember what and when to press. By using this remote controller, she could just press one button and remote would do everything for her.

I decided to use a power bank as a simplest solution, not sure whether it suits for this project. Use case for this remote would be: press power bank button → press button on tv remote → wait for it to finish its job → turn off power bank.

If there is something I should know, that can damage or in any other way cause problems, please let me know, as I said before I am newbie in electronics and never did anything before. I know that It would better for me to learn everything by reading books, but the problem is that I do not have that much time (more like time to wait for various elements to arive from ebay, on the other hand, I can buy a power bank anytime by going to a shop nearby, but it is really hard to get electronic components so quickly), I was wondering about using battery holder(2 AA battery holder) and somehow power arduino by using them, but as I know that would require another button to close the circuit and start powering arduino?

If Your grandma can remeber that sequence of button pressingsI think Your idea is good.

One thing I have had problems with, using IR macros, is I'm usually trying to turn on several items. If one is already on, then hitting the power button turns it off while all the others come on. "Grandma" can't fix it.

Some rare remotes have separate "on" and "off" buttons which remove this ambiguity. Search the remote codes for your devices thoroughly. Even if the supplied remote doesn't have separate buttons, the device may accept separate codes.

If Your grandma can remeber that sequence of button pressingsI think Your idea is good.

She turns TV off by unpluging it from the socket. So when it plugs it again it automatically turns on. I do not have that problem with turn off/on because my remote controller assumes that TV is already on.

So, do USB power bank is good in my case? 5V output 2A/1A?

If You install a plugg for the battory, pwr bank, it will work. When the device is plugged, powered up, some extra waist current be needed to keep it running. In order to preserve pwr unplugging is needed.
My pwr banks switched of within some 10 - 20 seconds. Combine that with Your grandma, what will she need to feel comfortable with the remote? Some psychology needs to be applied to the question.
Using "waist current" can work provided that the unit is put to charging during sleeping hours.

Maybe a kind of dead man switch, in reality a power switch, must be pressed when any other button will be pressed.
Many ideas….

2xAA or 2xAAA batteries, Pro Mini with power LED removed, keypad for the controls.

Keep the Pro Mini in deep sleep until a button is pressed (wake on pin change interrupt), have it send the IR code, and back to sleep. Then it's awake well under a second each time and your batteries will last for many years.

So I used power bank, it works fine, but sometimes I noticed, that when I connect arduino to power bank it immediately starts sending IR codes to TV, even tough button is not pressed. Why that happens ir is there anything I can do about that?


Is this still how the switch is wired? It looks like you have a 10K pullup to Vcc and that goes to an input. But the other side of the switch goes to Vcc where it should go to ground (input LOW when switch pressed).

And I do not see a current limit resistor for the IR LED.

And I do not see a current limit resistor for the IR LED.

As it flashes very short this may not be necessary - I have seen the same done with a 7-segment display, no current limiting resistors, instead limiting the time the current flows to keep things from breaking.

In this case instead of the resistor a power driver may be appropriate: in regular TV remotes those LEDs are driven at pretty high currents for high brightness, the flashes lasting fractions of a millisecond makes this possible.