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Arduino General ( Beginner )

Arduino General ( Beginner )

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Home Forums Hardware Arduino Arduino General ( Beginner )

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This topic contains 30 replies, has 2 voices, and was last updated by  stan 1 month ago.

Viewing 15 posts - 1 through 15 (of 31 total)
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  • 7700

    stan
    Participant

    Hi folks. I saw that all is talking about leds, strips, hard codings, shields, motors etc.. Thats not helping beginners. So i wanted to make a General About Arduino topic for beginners to ask simple “Starter Logic” questions before get more pro on arduino. As one of my friends said ;

    “There are no stupid questions! We all had to start at some point!”

    I m the first! Haha. Okay in my researches i see that we supply arduino via usb and dc jack and vcc pin and also 5v pin. Usb feeds a clear 5v to operate. Dc jack and vcc pin has 7v-12v need because they integrated via a voltage regulator which gives arduino a clear 5v also. But 5v pin which meant to give u an Output for ur devices can be also used as a voltage Input! Wow. Okay.. but its lil dangerous because 5v pin has no voltage regulator so u need to be sure u give a clean 5V to this pin to not to fry ur board. Here is the case; i see in some of projects people give 5v from 5V pin. But in an article its said they dont advice this. But only extetnal supply i cld find is 5v. And also this will feed my led strips too. so i feel i must feed arduino with this 5v pin. Do i need to afraid or what?

    7702

    hans
    Keymaster

    Hi Stan,
    thank you for starting this topic! 
    First off, under normal circumstance (not much connected to the Arduino) a simple 2A 5V USB power-supply, for example from your phone, or a cheap one from AliExpress, eBay of Amazon, would do the trick. The 5V feed from the USB port of a computer is is sufficient as well – as seen when programming the Arduino.
    If however, you need to power something that is power hungry, for example a LED strip, then a stronger power-supply is recommended.
    Here we would see two scenario’s;

    1) The Arduino is still connected to a PC. 
    This can be in scenario’s where you are still developing, or when the PC provides the Arduino with data (see the Boblight project for an example).
    In this case the LED strips need to be powered separately, since neither Arduino nor PC can really handle this much load on their pin’s or USB port.
    It is important that +5V does not get mixed though, as seen in the figure 4 of the Arduino and WS2812 article

    2) The Arduino is not connected to a PC. 
    In this case, the power supply for the extra components (LED strips for example) can be used to power the Arduino. See figure 5 of the Arduino and WS2812 article.
    Now we do want to be careful with this of course – in the depicted example the power-supply is 5V regulated, so that will work.
    If however your power-supply is not 5V (9V or higher) then the extra connector can be. But … be careful here as well, the regulator can handle on so much, so make sure you wire things correctly and do not try to pull 5B through your Arduino from, say a 9V power-supply, to feed the LED strips.
    In the end: learning a little about electronics is recommended if you decide to connect more components to your Arduino.
    • This reply was modified 1 month, 1 week ago by  hans.
    • This reply was modified 1 month, 1 week ago by  hans. Reason: Click the wrong button hahahaha :-)
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    7707

    stan
    Participant

    Thx for the explanation Hans. I ve seen that article and i definitely have decided to make figure 5 already because i will need 5A to 10A. Hehe. Well its a big project. Ok then now i m sure i will 5V pin to feed my mega. But i think i will have a resistor between my strip and data pin as its said that way to protect the first led on the strip from power sparks(whatever is this i dont know but it sounds logical haha)

    7709

    hans
    Keymaster

    Haha, well, just keep in mind that figure only applies when the Arduino is not connected to your PC.
    So while you’re developing, you’d probably use figure 4 until your code is ready and the Arduino will run independently … 

    7711

    stan
    Participant

    Oh yes yes. No pc connection while its powered from the external!! Indeed i noted that!! Haha. It would be soo bad to see the smoke from the chip! 

    7713

    hans
    Keymaster

     … and the smoke from your PC would be even worse 

    7715

    stan
    Participant

    Haha yea but if i cant arrange true calculations about amperage and the true cable type then that 10A supply can fire up my room also.. wow i m little afraid now. I need a professional for that haha

    • This reply was modified 1 month, 1 week ago by  stan.
    • This reply was modified 1 month, 1 week ago by  stan.
    7718

    hans
    Keymaster

    Haha, well, it’s better to have a wire that is too thick, then too thin – but you’ll feel the wire getting warm when it’s too thin 

    7720

    stan
    Participant

    Yea i made some researches about that and i ve found this which is very popular ;
    https://www.amazon.com/gp/product/B008L3QJAS?psc=1&redirect=true&ref_=oh_aui_detailpage_o08_s00
    But i dont know the Diameter of the cable and i dont know how much diameter i need! Because if diameter is much then natural resistance of cable itself will reduce 5V( high school science lesson hehe) and if diameter is too low then firing up is a matter of time..

    • This reply was modified 1 month, 1 week ago by  stan.
    • This reply was modified 1 month, 1 week ago by  stan.
    • This reply was modified 1 month, 1 week ago by  stan.
    • This reply was modified 1 month, 1 week ago by  stan.
    • This reply was modified 1 month, 1 week ago by  stan.
    7726

    hans
    Keymaster

    There are several sources where you can find this info (I’ve attached a chart as well – source).

    For example the American Wire Gauge Table – which has a calculator at the bottom as well.

    I usually do not worry too much, just when Amps go beyond say 5A, then I observe the wire used in the Power Supply and match that. After a bit of use I feel first by hand if the wire gets warm, and if i can barely feel it with my hands, then I hold the wire against my lips to see if I can feel it to get warmer or not. Hands first though! 

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    7729

    hans
    Keymaster

      Oh I forgot to add: to use this chart for 5V, multiply the amps with 2 (since it’s calculated for a 12V system, so we roughly can have twice the load).

    7731

    stan
    Participant

    Hmm okay i have a problem.. why i double  the amperage. I no get it.. i need divide! No? Why? Haha. I m confused. Ok. 

    V=I.R  

    For example

    12=6.2 but i need 5v. Leta say 6v

    6=6.1. I keep 6A becauae it is what it ll take.

    So the resistance of cable goes divided. So i need divide the number in chart. Not double. I m stuck now!!

    7733

    stan
    Participant

    And also in the link below i gave wire link it is 22ga and its used for arduino. I find 16ga in same website and it says for bus, boats and vehicles use!! I dont get.. 22 ga is Down of 16 ga? 

    7735

    stan
    Participant

    http://www.firemountaingems.com/resources/encyclobeadia/charts/6404

    Okay as I Thought the ga measurement goes opposite hehe. So higher ga means thinner cable ..okay. but i still no get why i Multiply becauae i ise not 12 i use 5v so current is lower so i need thinner ga so why i Multiply with 2 . I need divide 2 ! 

    7737

    hans
    Keymaster

    Simply put, the cable thickness is rated by wattage (I’m sure someone will tell me this is not 100% correct, since not all the lingo is 100% correct and there are a few other aspects that matter, but it will give you the basic idea).
    Say a cable is rated for 120 Watt and we use 12V. 

    Watt = Volt x Amps

    so 

    120 W = 12 V x X A

    so X = 10. Running 12V this cable could handle up to 10A.
    However, when we use the same cable for only 6V:

    120 W = 6 V x X A

    This makes X = 20, and this cable can handle 20 A at 6 V (see: V divided by 2, then A multiply by 2).
    So now you see why Voltage and Amps calculate opposite. 
    For you other question: 22ga might not be suitable when 12ga is recommended. Thicker is better when it comes to the amount of power pushing through.

    • This reply was modified 1 month ago by  hans.
    • This reply was modified 1 month ago by  hans.
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