I have this robot. I have it running an Obstacle Avoidance sketch, using an HC-SR04 Ultrasonic Sensor module. My robot's arduino & its various modules are powered by 4xAA batteries. (Through the VIN pin) My Servos on the robot are powered by a separate set of 4xAA batteries.
When I plug my robot's Arduino into my computer's USB, the Obstacle Avoidance program works perfectly. When my Arduino is powered solely by batteries, the robot keeps detecting an obstacle even when there is nothing there.
I assume this is because the HC-SR04 is not getting enough power to function properly. How would you recommend I beef up the power output of the Arduino, so everything has plenty of power? Can I just plug in a 9V battery to the barrel connector AS WELL AS the 4xAA batteries? I assume you can, I just want to make sure so my Arduino doesn't explode!
stupid-questions:
recommend I beef up the power output of the Arduino,
I guess you mean power input. If you mean a 9v PP3, it has virtually no power at all, and I don't think it will do anything more than just add some weight. Try 6xAA. No matter what you use, I submit you will do better by installing a decent 5v regulator and applying power to the 5v pin. If you do that, even your 4xAA might have a chance - for a while. At the moment they have none, as the required voltage at the barrel jack is 7.5v minimum. Another possibility with a decent regulator is 2x18650.
Nick_Pyner:
I guess you mean power input. If you mean a 9v PP3, it has virtually no power at all, and I don't think it will do anything more than just add some weight. Try 6xAA. No matter what you use, I submit you will do better by installing a decent 5v regulator and applying power to the 5v pin. If you do that, even your 4xAA might have a chance - for a while. At the moment they have none, as the required voltage at the barrel jack is 7.5v minimum. Another possibility with a decent regulator is 2x18650.
So, lemme get this straight.
You're saying don't use the VIN Pin at all. Just get 6xAA, and plug that into a 5V regulator, and then plug the 5V regulator directly into the 5V pin, powering the Arduino and everything else directly?
With that system, can't I just use my 4xAA with the 5V regulator? I mean, either way power output from the regulator will be the same. (5V) So would it really make a difference between 4xAA and 6xAA when you have a regulator like that?
Regulators have a voltage drop. You always have less coming out than going in. You need the margin.
The standard LM1117 drops 1.2v, and that's considered a low dropout. To get 5v you need to put in at least 6.2v. Arduino calls it 7.
INTP:
Regulators have a voltage drop. You always have less coming out than going in. You need the margin.
The standard LM1117 drops 1.2v, and that's considered a low dropout. To get 5v you need to put in at least 6.2v. Arduino calls it 7.
I see. So 4xAA would only generate 6V. What about a standard 9V battery?
EDIT: Wouldn't 6xAA batteries = 9V??? I'm not really sure...
they don't make 9v bricks with enough amp hours to be reliable power for an arduino with attachments.
the recommendation is to change the arduino supply to MORE AA's in series feeding 5v regulator with a higher amp output than the one on the arduino and leave the other supply the same as you have now.
I have a 4xAA pack and a 2xAA pack. Could i wire them in series to equal 6xAA? How would I wire them together? I assume its negative of one pack to positive of the other, correct? (If I don't want to wait for shipping?)
stupid-questions:
I have a 4xAA pack and a 2xAA pack. Could i wire them in series to equal 6xAA? How would I wire them together? I assume its negative of one pack to positive of the other, correct?
Yes, that's fine, you then have a 6 cell battery, and if it is made of 1.5v AA cells nose to tail, you have a nominal 9v. This will quickly drop to about 7.5v under load, hence the need for so many. 6xNiMH have more grunt, even though they are only 1.2v each.
You don't need an adjustable regulator, just a simple LM7805 module will suffice - $1.41. There is another little one that will deliver 5v 800mA from only 6v input and costs a dollar.
None of this means you must use a regulator, it is simply a good idea. Your real problem, caused by the 9v PP3, is not volts, its amps and, if you use a decent battery, you can get away without the regulator. The main reason for using an external regulator is that the on-board one is so inefficient. This becomes depressingly evident when you put your finger on it, and more so when you use batteries.
Nick_Pyner:
]Yes, that's fine, you then have a 6 cell battery, and if it is made of 1.5v AA cells nose to tail, you have a nominal 9v. This will quickly drop to about 7.5v under load, hence the need for so many. 6xNiMH have more grunt, even though they are only 1.2v each.
You don't need an adjustable regulator, just a simple LM7805 module will suffice - $1.41. There is another little one that will deliver 5v 800mA from only 6v input and costs a dollar.
None of this means you must use a regulator, it is simply a good idea. Your real problem, caused by the 9v PP3, is not volts, its amps and, if you use a decent battery, you can get away without the regulator. The main reason for using an external regulator is that the on-board one is so inefficient. This becomes depressingly evident when you put your finger on it, and more so when you use batteries.
I kind of want to TRY and use the ajustable regulator. (I want it to come soon! :o) Plus, I can use it on future projects where I can adjust it as-needed So I know I don't NEED it, but CAN I use it?
So I know I don't NEED it, but CAN I use it?