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61  Using Arduino / General Electronics / Re: Connecting a TinkerKit Mosfet directly to an Arduino on: May 10, 2014, 04:40:25 am
The TinkerKit Mosfet module using IRF520 MOSFET was not logic level MOSFET so you need to drive the MOSFET with minimum 10V apply to the V+ and GND terminals.
62  Using Arduino / Project Guidance / Re: Random int on: May 09, 2014, 05:59:43 pm
http://arduino.cc/en/reference/random

http://arduino.sundh.com/2012/11/decision-maker-with-leds/
63  Using Arduino / Project Guidance / Re: How can I use a motorshield with arduino to run an eggbot? on: May 09, 2014, 10:03:18 am
Have you check these out?
https://github.com/thunderbug1/Spherebot-Host-GUI
https://github.com/coredump-ch/eggbot
64  Using Arduino / General Electronics / Re: [Help on searchig] IC for switching ON \ OFF on: May 07, 2014, 10:32:44 am
Or you can use circuit like this


65  Using Arduino / General Electronics / Re: [Help on searchig] IC for switching ON \ OFF on: May 07, 2014, 07:45:43 am
You may like to take a look at this

Pololu Pushbutton Power Switch LV
http://www.pololu.com/product/751
66  Using Arduino / Project Guidance / Re: HC-SR04 Ultrasonic Sensor Not Working When Using Motor Shield on: May 04, 2014, 05:19:36 am
Have you read this reply?
It was fixed easily enough by shifting the Trig and Echo pins for the sensor to 4 and 7 respectively on the MotorShield and making the change in the sketch definitions.
the Arduino Motor Shield R3 uses A0 and A1 for current sensing capabilities.

Did you manage to make progress on this issue?  I had the exact same problem, as a complete beginner using the tutorial from Miguel Grinberg's blog (which I presume is the same one you mention, as he suggests using the A0 and A1 pins as digital 14 and 15).

It was fixed easily enough by shifting the Trig and Echo pins for the sensor to 4 and 7 respectively on the MotorShield and making the change in the sketch definitions.  I'm still wondering though why A0 and A1 stopped working when the MotorShield was placed...

EDIT: The issue turns out to be a very simple one (we all have to start somewhere, right?) in that the Arduino Motor Shield R3 uses A0 and A1 for current sensing capabilities.  In the end it was a RTFM problem, combined with following a tutorial that used a different motor shield.
67  Using Arduino / Project Guidance / Re: Difference between Mega 5v and Due 3.3v? on: May 02, 2014, 06:20:12 pm
This is borrow story from other forum.

When the Fab scales down for the next technology, the gate oxide thickness in MOS transistors must also be reduced. The big jump was from 0.5um to 0.35um technologies. This was really the first time when gate oxides were reduced below 10nm. At 10nm, the gate oxide can hold off 8Volts so it can easily be used for 5Volts. Since everyone that made power supplies only guaranteed on +/-10%, that meant the MOS must be reliable at 5.5Volts. Two problems : one is that a 10nm oxide when it gets above 8V it starts to tunnel electrons through it. That is how they can be used in EEPROMs and Flash. But worse than this, at high drain voltages hot electrons are injected into the channel and bulk of the Si. These can implant themselevs into the gate ioxide causing unreversible damage (unlike the tunneling case). So the 10nm oxide also had to withstand hot electrons from drain voltages at 5.5V.
OK so we want to shrink to 0.35um. Unfortunately it is not worth shrinking if you do not shrink vertically as well a laterally. Next best oxide was around 7nm. This starts to tunnel close to 7 volts and cannot withstand hot electrons from 5.5V on the drain. So the fab industry said:
"We want to lower the power supply to below 5V" with a big cheesy smile expecting nothing but complete compliance.
The board industry (in particular PC motherboards) said :
"Not frickin likely - in you dreams !"

So the fab industry got extremely upset at this and went off and engineered around it. Two gate thicknesses, 1 to interface with those really mean board people at 5.5V and one just for the boys. 3.6V was chosen as the max to provide enough for high speed drive capability and good immunity to hot electrons. Since the power supply guys live in the eighteenth century the maintained +/- 10% so 3.3V was chosen as centre 3.0V to 3.6V.

Then one day, a fab with enough muscle went to the board guys and said:
"You go 3.3V or you dont get any pentiums"

The board guys then said
"Stuff you we'll go AMD"

To which the fab guys said
"Only kidding! You can stay 5V"

Then one day another fab guy with muscle said
"3.3V or nae Athlons!"
To which the board guys said
"Oops!"

Then all the boards went to 3.3V. The fab guys feeling really pleased with themselves said "Lets shrink to 0.18um and annoy the hell out of the board guys!"
At 0.18um, gate oxides were reduced to about 3.5nm. This oxide can only stand about 2.5V on the drain for hot electrons. So the fab guys went for 2.0V max about 3-4x the threshold voltage. With +/-10% stuck hard, this meant 1.6V to 2.0V so 1.8V nominal.
And then they all went back to start annoying the board guys again.

The boards are still about 3.3V nominally although some chips are still 5V
68  Using Arduino / Project Guidance / Re: UNO and motor shield power on: May 02, 2014, 12:11:15 pm
From the datasheets
The L298 has a total voltage drop of 2.55V (typ.) at 1A load and 3.7V (typ) at 2A.
The minimum drop possible at 1A is 1.8V
The guaranteed maximum drop at 1A is 3.2V (4.9V at 2A)

The motor shield R3 have Current sensing which is 1.65V/A and 3.3V for 2A

So you will get 5V to 6V voltage drop in total then you will need a 12V battery, if you use voltage between 7 and 12V then no need to disconnect the VIN pin on the motor shield, you only disconnect the VIN pin on the motor shield when you use voltage above 12V.

 

69  Using Arduino / Project Guidance / Re: Is There Any Simple Way To Combine Sketches? on: May 01, 2014, 05:57:16 am
Read this "Demonstration code for several things at the same time" by @Rebin2 Robin2
you will able to see how to do things at the same time
http://forum.arduino.cc/index.php?topic=223286.0
70  Using Arduino / Project Guidance / Re: Merging Two Codes? on: May 01, 2014, 01:24:48 am
Read this
http://forum.arduino.cc/index.php?topic=223286.0
71  Using Arduino / Project Guidance / Re: Building a RC Car on: May 01, 2014, 01:15:13 am
You may try this with some wireless modules

http://www.pololu.com/product/2506
72  Using Arduino / Project Guidance / Re: Problem with arduino Duemilanove!! HELPPP on: April 28, 2014, 08:01:57 am
I have look through your posted pics and I have found that you have wired the LED the wrong way like this.



This way the resistor will not limit the current for the LED and your will damage your Arduino out put pin.
The resistor have to be in series with the LED in the circuit.
The correct way to wired your LED will be like this


In-case you have  miss the BreadBoard connection will look like this





 
73  Using Arduino / Project Guidance / Re: Problem with arduino Duemilanove!! HELPPP on: April 27, 2014, 09:36:30 am
Your green wire connected to a resistor but the other end of resistor was open.

You are saying the RGB LEDs you are using are 6 pin.
Is it
Three cathodes, three anodes? Basically, three separate LEDs in one enclosure?

or

1 anode Red
2 anodes Blue
1 anode Green
2 common cathodes
74  Using Arduino / Project Guidance / Re: Problem with arduino Duemilanove!! HELPPP on: April 27, 2014, 08:05:02 am
Please post a picture show us how you connect up.
75  Using Arduino / Project Guidance / Re: Problem with arduino Duemilanove!! HELPPP on: April 27, 2014, 07:44:57 am
Your greenPin using  pin 8 was not a PWM pin will not work with analogWrite()
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