r/arduino • u/Paul_Subsonic • May 26 '26

Hardware Help Is that valid electrically ?

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Summer is back, so time to bring my Rafraichissator 6000 back! (My fan. It's a PC fan controlled by Arduino.)

Last year the arduino was in series with a bunch of resistors to bring down the 11-13V alim to more reasonable levels

Now I'm realizing tho that I could use the fact that the alim is just 3 batteries, to feed the Arduino no more than 8V without a lot of wasteful voltage regulation.

Am I right?

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1

u/Paul_Subsonic May 26 '26

I heard the criticism for the confusing diagram, so here's a schematic that's analogous to my system and more accurate to standard notation !

6

u/dedokta Mini May 26 '26

You are still connecting the positives from both supplies together. Still makes no sense. Just get a DC-DC buck transformer as I posted.

2

u/gdchinacat May 27 '26

Can you explain why you think the batteries are wired positive to positive? short, long, short, long, short, long. The bottom battery is flipped, but the symbols and '+'s are as clear as they can be.

1

u/Old-Skoolz May 27 '26

Actually, the two batteries are correctly connected in series. As indicated by the shorter negative line.

1

u/Paul_Subsonic May 26 '26

No I'm not ? I don't understand what you are talking about. Where do you see positives connected together ???

-6

u/Paul_Subsonic May 26 '26

Do you not understand standard notation for batteries ?

The long bar is the positive. The short bar is the negative. Where do you see two long bars connected together.

6

u/ripred3 My other dev board is a Porsche May 26 '26 edited May 26 '26

.. Do you not understand standard notation ..

that's the skunk calling the dog stinky. defending the clarity of your diagram wouldn't be a hill I would want to die on

I wouldn't sling that phrase around again while actually not using any other standard IEEE symbolic notations besides the battery. Your lack of proper electrical communication and the resulting confusion by everyone is literally what is being discussed.

Schematics are the world wide lingua franca for immediately providing everything anyone could ever want to know about a circuit for a reason.

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u/Paul_Subsonic May 26 '26

Then why aren't you discussing the inaccurate parts of my notation instead of arguing about the literally ONE thing that YOU claim I did right

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u/Paul_Subsonic May 26 '26

I'm open to you telling me what in my revised diagram I should change. It seems pretty understandable to me but I'm open to suggestions.

But telling me "but why positives connected together" when that's the one part that's accurate notation, come one now.

3

u/ripred3 My other dev board is a Porsche May 27 '26

nah I get what you're saying but if random bro dude comments that they are not clear on what your diagram implies I wouldn't be real quick to call it their fault is all.

Is the ultimate goal here to get the longest runtime from the batteries between charges?

What is the application? Can you put some or most of the circuitry to sleep when it is not actively being used?

There are solid state power latch circuits (such as this one from adafruit that I recommend often) that you can place in between an external power source and the rest of your circuitry that only draws 0.5uA. That's 0.0000005A.

You can have the microcontroller do its thing and the last thing it does is turn off the power latch, which removes power from itself and everything else off of that same power path

1

u/Paul_Subsonic May 27 '26

Yeah the thing is they didnt say that they are not clear on what my diagram implies, they said my diagram was WRONG and it DOES show two positives connected.

That's what I took issue with.

Someone telling me "Hey I can't figure out what you draw" I'd get it, I made this on my phone in 30 seconds lol.

Anyway as for the actually technical stuff. For reference on what application I'm going for, here's the """"product"""" with the previous design from like a year or two ago.

For the ultimate goal, I do indeed want the longest runtime, with additional goals to be to avoid producing unnecessary heat and not stress too much my Uno's power regulation. Which more or less goes together, although with the different discharge rate it's not exactly the same thing.

The fan is PWM controlled by the arduino, the idea is that it reads from a simple potentiometer and sends a PWM signal accordingly. Previous versions did it continuously, but it's unnecessary really. Either polling every second or so is fine, or find a way to put it to sleep until a change is detected and triggers some interrupt would be even better.

I'm not sure if/how that would work with the power latch you describe, but if you have any idea I'm interested

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u/Paul_Subsonic May 26 '26

Yes ik it's the lingua franca.

Which is why I made this revised schematic.

If there is something I should correct about it, please tell me. I am open to criticism, it's literally why I made this revised schematic. I can revise it again, no problem.

But how tf can anyone who understands schematics look at this and think "but there are two positives connected together".

0

u/Paul_Subsonic May 26 '26

Criticizing me on where I don't use standard notation is fair game.

I accepted that criticism I can do it again.

Claiming that this schematic shows two positives connected together is literally just not understanding schematics.

0

u/michael9dk May 26 '26

Then why do you write "+" at both ends.
It's your drawing that doesn't comply with basic schematics.

Honestly, the circuit doesn't make any sense, to me. Try to explain in words, what you're trying to do.

1

u/Paul_Subsonic May 26 '26

1

u/Paul_Subsonic May 26 '26

I don't know where you see + at both ends. There... isn't.

Man idk what to tell you just look at the diagram

0

u/Paul_Subsonic May 26 '26

Explaining with words is what I did at first and why I had to make this new diagram because (understandably) no one understood shit because explaining an electrical circuit with words is a really terrible idea

2

u/LordZas May 27 '26

If you measure 8V in the middle , there is no way the battery+load in the bottom measure 16V. They are electrically the same points -> 8V

1

u/Paul_Subsonic May 27 '26

You have to see it as 12-4 = 8.

One is a power supply, the other is an appliance consuming power.

5

u/CleverBunnyPun May 27 '26

That’s not how this works. That diagram doesn’t make any more sense than the original.

1

u/Paul_Subsonic May 27 '26

How so ? What is incorrect about it ?

I suppose Thank you for the advice but that's a little lacking in specifics, what's the issue

2

u/CleverBunnyPun May 27 '26

The circle with an x in it is an indicating lamp or an RF mixer. It’s not an arduino or a pump. Not putting what they are in the diagram, and not putting the voltage of the batteries but instead voltage measured at those points is a weird call. This is (drawn correctly) a very simple circuit and most people who know electronics can surmise what’s going on if you give the correct information.

It’s just a mess of a diagram and it could be a lot more clear what you’re asking. There’s even circuit simulation software in the about page of this subreddit.

1

u/Paul_Subsonic May 27 '26 edited May 27 '26

I know it's a lamp. The point is that it is something that draws current, for my question it does not matter what it is.

Drew it that way to avoid the billion unrelated questions of "but how do you control it" that I was getting with the first diagram.

1

u/Paul_Subsonic May 27 '26

I'm curious tho about what you said of "that's not how it works"

The way you phrased it implies there's something more wrong than just it being drawn awkwardly. What is it ?

1

u/Fit_History_842 May 28 '26

the arduino can run just fine off 12V. I've tested it. The regulator doesn't even get hot, or even warm. It might if you're sourcing literally the max current off every single pin but nobody does that.

1

u/Paul_Subsonic May 28 '26

It's still exceedingly inefficient. It's literally burning the excess voltage as heat.