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Topic: 9v to 5v for arduino pro mini (Read 2 times) previous topic - next topic

sholtob

i am using an arduino pro mini with a nine volt battery, i need to turn that into 5v to power the arduino and also sensors and motors runnign from the battery, when i use it the atega chip heats up so i dont like to continue using it, i would use ohms law to work it out but y multimeter is broken and i dont knpw the current of the battery.
thanks very much, i am trying to make a parachute release mechanism for a water rocket so the arduino needs to be small.

CrossRoads

You have the 9V connected to the RAW pin?
The sensors/motors run from the 9V?
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retrolefty

A Motor using those small 9 volt batteries are almost always a losing situation.

Lefty


sholtob

there is a tilt sensor attached directly to  the 9v pin, the power shouldn't damage the sensor, im just worried that the power going into the arduino through the digital pin from the sensor is damaging the arduino, i need to know which value of resistor to put between the battery and the raw pin to avoid damage to the arduino and the servo, thanks very much :)

retrolefty

Quote
i need to know which value of resistor to put between the battery and the raw pin to avoid damage to the arduino and the servo, thanks very much


Wrong solution for the wrong problem. Powering a servo from the pro mini's +5vdc power is what will overheat the regulator. That's if the little 9 volt battery can even supply enough current to overheat anything.

I think you need to reevaluate all your loads for what current they draw, what voltage they require, how long the project must run between battery replacements. Only then can you see what size battery your project will require. Those little 9 volt batteries don't work with servos worth a darn......

Lefty


sholtob

it is a very small servo, i prototyped it on a freeduino and a breadboard and the 5v from the arduino was enough, it only needs to move 180 degrees to release the parachute so it isnt going to drain the battery quickly,

retrolefty


it is a very small servo, i prototyped it on a freeduino and a breadboard and the 5v from the arduino was enough, it only needs to move 180 degrees to release the parachute so it isnt going to drain the battery quickly,


OK, so what is the problem you are having, not the solution you think you need to apply (adding a series resistance to the battery is almost never a solution worth pursuing).


Lefty

sholtob

the problem is the arduino chip is heating up

retrolefty

Well the pro mini is designed to handle 9vdc input to it's raw pin and uses it's on-board voltage regulator to create the +5vdc needed by the AVR chip.

Maybe if you could draw up how you are wiring everything up (battery, pro-mini, servos, sensor), we can see what's what. What specifically is getting hot, the 328p chip? the voltage regulator chip?

Lefty


sholtob

as i said, the problem is the power going through the tilt switch into digital pin 2, so if you know the value of resistor that would be best for turning 9v into 5v so that it is the same as the output on a normal arduino board?

retrolefty


as i said, the problem is the power going through the tilt switch into digital pin 2, so if you know the value of resistor that would be best for turning 9v into 5v so that it is the same as the output on a normal arduino board?


Could you provide the datasheet for the tilt switch? If it's a simple switch contact why don't you just wire it to +5vdc rather then +9vdc?

Lefty


AWOL

Have you mentioned a tilt switch before?
Why don't you tell us what you've got and what you want to do?
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

sholtob

i mentioned the tilt switch in my first post, i had no idea there was a 5vdc output on the pro mini, can you describe where it is?, thanks very much for all the help by the way :)

AWOL

I'm afraid you're going to have to point me to the tilt switch reference in the first post.

Punctuation would be useful too.
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

sholtob

Quote
there is a tilt sensor attached directly to  the 9v pin

it was actually in my second post but i did mention it. i got the circuit to work on a breadboard with a freeduino so i know that it works. and i do punctuate quite allot actually.

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