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1  Using Arduino / General Electronics / Re: Arduino Motor Shield - Voltage Supply on: August 19, 2014, 01:30:44 pm
The mega has an automatic voltage selecting circuit that should only allow it to be powered from one source at a time . I would have to look at the schematic to be sure, but I think the barrel plug takes precedence over usb.
2  Using Arduino / General Electronics / Re: Does a LM7809 help me boost arduino uno's 5V to 9V? on: August 16, 2014, 05:39:30 pm
Dc - dc boost converters like xl6009 or lm2577 will take 5v and boost it up to 9v ( with the help of additional components). This type of converter can easily draw several amps depending on what it powers, which would burn up the arduino. Running it directly from the arduino is ill advised, but  it should work if you power from an external 5v source. Can you explain in detail what you trying to do? Check Google for info on buck - boost converters or Switched Mode Power Supplies smps.
3  Using Arduino / Motors, Mechanics, and Power / Re: help with motor project on: August 06, 2014, 07:49:56 pm
you might do something like:  digitalread ForwardButtonPin.  if it is high, analogread PotPin and map the analogvalue to functional rpm speed of your motor, and set the stepper stepping. Repeat for ReverseButtonPin. This approach might look something like this:
Code:
byte forward = digitalRead(ForwardButton);
if (forward == HIGH)
{
 // read the analog in value:
  sensorValue = analogRead(PotPin);           
  // map it to the range of the motor speed:
  rpm = map(sensorValue, 0, 1023, 0, 255);  // change 255 to the top speed of your mootr
 
  myStepper.setSpeed(rpm); //set the rpm speed
  myStepper.step(stepsPerRevolution/100); //move a few steps forward
}
byte reverse = digitalRead(ReverseButton);
if (reverse == HIGH)
{
 // read the analog in value:
  sensorValue = analogRead(PotPin);           
  // map it to the range of the motor speed:
  rpm = map(sensorValue, 0, 1023, 0, 255);  // change 255 to the top speed of your motor
  // change the analog out value:
  myStepper.setSpeed(rpm); //set the rpm speed
  myStepper.step(-stepsPerRevolution/100); //move a few steps backward
}
i'll let you define the appropriate variables as you see fit
4  Using Arduino / Motors, Mechanics, and Power / Re: Powering Neopixels and Arduino board from one adapter on: July 30, 2014, 02:06:20 pm
Vin provides power to the input side the voltage regulator which regulates the voltage from the Vin pin down to 5volts on the output side which is also connected to the 5v pin. Vin and the barrel plug are basically the same and require 7-12volts. To run the v.reg. The notable exception is that there is a protection diode connected between Vin and the plug. So the barrel plug has reverse polarity protection, but Vin does not because it is after the diode.
5  Using Arduino / General Electronics / Re: How will moisture affect an Arduino? Rain? on: July 29, 2014, 09:04:56 pm
Humidity is probably OK, but excessive condensation could cause problems.
6  Using Arduino / Motors, Mechanics, and Power / Re: help with motor project on: July 29, 2014, 08:51:07 pm
I did understand, and yes you did ask how to connect it. No, i wont write your code for you, (but someone else might). However, everything you need to know is in the arduino IDE, and any specific questions you might have we would be happy to answer for you. Yes, someone will help you with your code, but you first have to post whatever code you have even if it is just the example sketch and be specific with your questions. 1)Start with the example sketch and get your motor moving, 2) once you know the example code works, add a button input. 3) if you run into problems report back here and post your code.
7  Using Arduino / Motors, Mechanics, and Power / Re: help with motor project on: July 26, 2014, 06:17:39 pm
i would say start by doing some homework.
1)make sure you know how stepper motors work and what type yours is exactly.
2) look up the datasheet for the uln2803 and make sure it can handle the current drawn by the motor. the datasheet will usually provide you  with enough info to connect it up.
3) learn to use the arduino. work through the examples in the IDE under Basics, Digital, analog, control and stepper. "stepper" should have most of the code you need, the rest you can probably just cut and paste .
8  Using Arduino / Motors, Mechanics, and Power / Re: help with motor project on: July 25, 2014, 11:26:12 am
What questions do you have? Show your code. How do you plan to wire it up? Show a schematic. You could do this with just one potentiometer. When the pot is in the center, the motor is stationary. As you twist the pot off center the motor will spin faster one way or the other.
9  Using Arduino / General Electronics / Re: Uno - how much current can Vin supply? on: July 24, 2014, 04:03:37 pm
Yep that's the idea. It is hard to say what the actual current will be that the vreg will source at 9v. Temperature plays a major role since the regulator will shutdown as it goes into thermal overload. Doesn, t necessarily hurt anything, but it is best to avoid frequently over stressing the part. The Basic rule of thumb is if the part is too hot to keep your finger on, you're probably overdoing it.
10  Using Arduino / General Electronics / Re: Uno - how much current can Vin supply? on: July 24, 2014, 03:45:59 pm
Yes lucky that vreg would power the arduino. If put twelve into the barrel you'll get slightly less than 12 at Vin- no good for addressable leds. Just plug your LED's into the 5v pin. You'll be limited to maybe .5 amp or so from the regulator. Better to just power everything from the 5v source.
11  Using Arduino / General Electronics / Re: Uno - how much current can Vin supply? on: July 24, 2014, 03:14:13 pm
You need to feed 7-12v to the input barrel to power the voltage regulator which can source 800 ma at 5v to the arduino and 5v pin under ideal conditions. Same goes for sourcing power to the Vin pin except you have no polarity protection. You can plug a  well regulated 5 v source directly into the 5v pin and also run your LED's off the 5v pin. If you feed 7-12v into the barrel, Vin will supply about  an amp at whatever input voltage you provide minus .5-.7v loss incurred by the protection diode.
12  Using Arduino / General Electronics / Re: Power Supply questions on: July 22, 2014, 12:01:32 pm
Quote
The leakage current is under 1mA, which means the outputs could be floating
at mains voltage levels if not tied to PE somewhere - recommended unless you have
a genuine reason not to.
I would get shocks from my bench supply because i leave  Jumper wires sticking out of the Ground rail on the breadboard. Every now and then my elbow would brush across one and i would feel a sharp stinging sensation. It took a few times  to realize what was going on.  Probing V- wrt ground shows about a 30 volt difference :/.
13  Using Arduino / General Electronics / Re: Power Supply questions on: July 22, 2014, 11:37:02 am
I would agree with Fungus. "V-" is the DC negative return path which is probably isolated from earth ground . Earth ground should be connected to mains grounding system for safety. In any case Probe it to be sure. Rarely, these cheap SMPS power supplies are dual voltages unless specifically marked. If you use Vin, you best be absolutely sure of your polarity.
14  Using Arduino / Programming Questions / Re: I just do not understand these output voltages on: July 22, 2014, 11:10:47 am
a schematic and picture might be helpful. what value resistors are you using? its always smart to initialize your inputs as well.
15  Using Arduino / Project Guidance / Re: How rugged is Arduino? on: July 21, 2014, 07:09:59 pm
Reliable and rugged are to different things. arduino is very reliable within its specified operating conditions. Outside of its Safe Operating Area- all bets are off. What specific application did you have in mind?
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