# a few questions about electronics

Thread Starter

#### Dankest

Joined Jun 4, 2017
3
I am a complete noob with all this stuff, but that is why i am here, so i have a arduino and it came with a motor, but when i hook the motor to the chip, it turns the motor on and the motor spins for a few seconds, and then the board turns off and goes very hot, i understand that the motor is probably drawing too much current, so would sticking a resistor make it work or would that draw more current. Also does using a resistor make a battery run out faster?

last question : people keep saying that a motor will draw as much current as it needs, but what about voltage the higher the voltage the faster, my dc brushed motor will go, but i know that attaching this to a car battery will burn it out, why and how can i stop this, i could use a resistor but do they lower voltage?

I know these are stupid questions, but you know i don't have the answer and there something i struggle to understand, if you answer and have a nice day.

Moderaters notes:
Please using comma in your sentences and seperate the appropriate sentences to another paragraph, the ',' had been added into your sentences.

#### BR-549

Joined Sep 22, 2013
4,938

#### MrChips

Joined Oct 2, 2009
22,069
A lot of your questions can be answered with knowledge of one basic principle, Ohm's Law.

Ohm's Law states that the current through a resistor is directly proportional to the applied voltage and inversely proportional to the resistance.

We can state this in algebraic terms as I = V/R,
where I is the current through the resistor
V is the voltage across the resistor and
R is the value of the resistance.

Let's take one thing at a time.

1. If a motor is designed to operate at 5V, it will demand a certain amount of current based on its resistance. (The current will increase if you load down the motor). If you connect the motor to 12V, you will draw more current and burn out the motor.

2. If you put a resistor with the appropriate value resistance in series with the motor, you reduce the current through the circuit. Since the current drawn from the battery is reduced, the battery will last longer.

3. The motor is designed to run at a certain voltage and will draw a certain amount of current. If you load down the motor mechanically the current demanded will increase. (This is for another reason which we can side-step for this discussion.) The microcontroller (MCU) output pin is not designed to supply this amount of current. Hence the MCU could run hot and you can damage the MCU.

#### MaxHeadRoom

Joined Jul 18, 2013
21,607
@Dankest If powering a device that requires current the MCU cannot supply, then typically a Mosfet or small Fet (electronic switch) can be used, a 2N7000 for a start.
Max.

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#### dl324

Joined Mar 30, 2015
11,845
Welcome to AAC!

You'll make it easier for members to read and understand your posts if you use paragraphs to organize your thoughts. Also, proper sentence structure is always appreciated.

This is what your post would look like using paragraphs:
i am a complete noob with all this stuff but that is why i am hear

so i have a arduino and it came with a motor but when i hook the motor to the chip it turns the motor on and the motor spins for a few seconds and then the board turns off and goes very hot i under stand that the motor is probably drawing too much current so would sticking a resistor make it work or would that draw more current.

Also does using a resistor make a battery run out faster.

last question people keep saying that a motor will draw as much current as it needs but what about voltage the higher the voltage the faster my dc brushed motor will go but i know that attaching this to a car battery will burn it out why and how can i stop this i could use a resistor but do they lower voltage?

i know these and stupid questions but you know i don't have the answer and there something i struggle to understand ty if you answer and have a nice day
I didn't correct grammar...

A resistor is generally not required in series with a motor. You should use the voltage specified for the motor. Pay attention to the current required.

A resistor would reduce the drain on the battery (P = V*V/R), but the motor might not function properly if the voltage is reduced too much.

Ignoring the voltage requirement of the motor is a bad idea. Too low and the motor will stall, drawing high current. Too high and the motor might burn out.

#### crutschow

Joined Mar 14, 2008
25,634
I'm with dl324.
You need to improve your post writing
It is so run together and rambling, making it very hard to read, that I stopped after a couple sentences.

#### Reloadron

Joined Jan 15, 2015
5,667
Since you are using an Arduino and in the interest of keeping things simple. The Arduino Motor Shield is likely a good solution. Yes, you are likely overloading the Arduino uC. You can use a basic transistor or a few field effect transistor versions but using an Arduino Motor Shield opens the door for heavier loads and fits together with your existing Arduino board with everything marked up for you. There are other assorted motor drivers out there but again the Arduino Motor Shield keeps things simple.

Ron

#### shteii01

Joined Feb 19, 2010
4,644

#### atferrari

Joined Jan 6, 2004
4,110
@Dankest If powering a device that requires current the MCU cannot supply, then typically a Mosfet or small Fet (electronic switch) can be used, a 2N7000 for a start.
Max.
Thanks to your persistent preaching of the ubiquitous 2N7000, some time ago I started to finally use it with satisfactory results.

#### MaxHeadRoom

Joined Jul 18, 2013
21,607
I have used them since their inception in the early 90's I believe.
I rarely use bi-polar transistors now.
Max.

Thread Starter

#### Dankest

Joined Jun 4, 2017
3
Sorry for the mistakes I made English has never been my strong point. I will make sure to check next time.

#### dl324

Joined Mar 30, 2015
11,845
Sorry for the mistakes I made English has never been my strong point. I will make sure to check next time.
If English isn't your native language, you could write in your native language and use a translator.

#### MrChips

Joined Oct 2, 2009
22,069
Sorry for the mistakes I made English has never been my strong point. I will make sure to check next time.
I speak HM's English and yet it took me three tries to pass my 'O' Levels.
Not to worry, I have proven that you can get better with age.