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1336  Community / Products and Services / Re: South African suppliers on: February 09, 2014, 01:00:08 am
If you're looking for a supplier of screws and such in Joburg, Bolt Nut are in the CBD. They've moved from where the website says, but literally round the corner; diagonally opposite central fire station.

And My Hobbies in Krugersdorp for servos and related.
1337  Community / Website and Forum / Re: Problem with main Arduino website 8 Feb 2014 on: February 09, 2014, 12:42:00 am
How about www.arduino.cc? That's the problem site.

I get the redirect loop message there
1338  Using Arduino / Project Guidance / Re: How to make pins 22 - 53 of Mega go low on: February 08, 2014, 11:43:32 pm
Have you tried other code using those pins? Maybe just load Blink and change the pin number- that way at least you'll have the world's most basic sketch and eliminate any other potential source of problems.
1339  Community / Website and Forum / Re: Problem with main Arduino website 8 Feb 2014 on: February 08, 2014, 11:35:29 pm
I'm getting the re-direct loop thing on the Reference page: I'm in the Forum though as you can see.
1340  Using Arduino / Project Guidance / Re: Can't get Arduion.cc DigitaReadSerial Example to work. PLEASE HELP on: February 08, 2014, 11:14:54 pm
Quote
I don't know what you mean by "Surely not with an external pull down?"
Is my wiring wrong?

I added INPUT_PULLUP, but it didn't seem to make any difference.

Sorry, that one was for LarryD.

Pullups and Pulldowns are mutually exclusive and Larry hadn't realised there was a pulldown.

EDIT.... one other thing to check, is that you have the switch oriented correctly on the board. I can't see the legs in the photo, but those square, 4leg switches are often 90 degrees out. Look at the pic I attached of a typical switch and see if you have the switching correct. Might be an idea to get your ohm-meter out and satisfy yourself which pins are always connected and which are switched.
1341  Using Arduino / Motors, Mechanics, and Power / Re: Strange nano & servo behaviour on: February 08, 2014, 02:42:21 pm
Hmmmmm.

Do you know your PS is good?

If you have a holder for 4xAAs, try running the servos off that?
1342  Using Arduino / Project Guidance / Re: Can't get Arduion.cc DigitaReadSerial Example to work. PLEASE HELP on: February 08, 2014, 02:25:29 pm
Try:
  pinMode(pushButton, INPUT_PULLUP);

Surely not with an external pull down?

Add the line below so you can see if the comms is working at all

Code:
void setup() {
  // initialize serial communication at 9600 bits per second:
  Serial.begin(9600);
  Serial.println("Starting serial comms....."); //<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

And as suggested, post a pic of your actual circuit, not just the one from the book.

1343  Using Arduino / Motors, Mechanics, and Power / Re: Strange nano & servo behaviour on: February 08, 2014, 01:42:14 pm
Have you got the ground from the PS to the servo AND to the Arduino ground? See pic attached, source: zoomkat.

(Btw, it's bad practice to power a servo from the Arduino.)
1344  Using Arduino / General Electronics / Re: lm35 external calibration on: February 08, 2014, 12:58:14 pm
Re the dipping it in the water thing.... presumably that's why distilled water, so there's no conduction? Or is the short across all three pins insignificant anyway?
1345  Using Arduino / Sensors / Re: DS1307 error on: February 08, 2014, 10:14:38 am
I've had great success with a couple of libraries from Henning Karlsen. I don't have a 1307, so I can't vouch for his 1307 library, but why not give it a try?
1346  Using Arduino / General Electronics / Re: lm35 external calibration on: February 08, 2014, 09:32:23 am
Quote
simply do a two point calibration (ice and boiling water),

That would assume you knew the local temperature at which water boils.
1347  Using Arduino / Project Guidance / Re: programming problem pleas help on: February 08, 2014, 07:51:42 am
Code:
if(val>800)// this mean 4 volt {
    for(i=0;i<255;i++)//this mean full duty cycle{
      analogWrite(motor,i);
      delay(10);}
  }
Do you understand what the "//" comment does?

yes it's mean comment to understand who read the code


But have a more careful look at that lines with the comment.

Hint: where is the "{" ?
1348  Using Arduino / General Electronics / Re: Absolute size of resistors in a voltage divider on: February 08, 2014, 02:17:53 am
Thanks guys
1349  Using Arduino / General Electronics / Absolute size of resistors in a voltage divider on: February 08, 2014, 12:17:12 am
Morning all,

I know that the output from a voltage divider is determined by the ratio of R1 to (R1 + R2) where R1 is on the input side.

But how do you figure out what absolute resistances you should use, as opposed to the ratio?

If I want a 50% output, that formula tells me I need R1 = R2. By that, they could both be 220 ohms  or 220 zillion ohms.

How do we know what general size of ohms - kiloohms - megaohms we should be using?


1350  Using Arduino / Motors, Mechanics, and Power / Re: I need help to control 2 dc motors with a ps2 analog joystick on: February 07, 2014, 11:45:16 pm
Here you have a complete tutorial controlrobotics.rodrigomompo.com

Nice site
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