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1  Using Arduino / General Electronics / Control speed of a DC motor on: March 09, 2014, 06:46:10 am
Dear users,

What is the best way to control the speed of a DC motor? I've tried to control both a PC fan and a DC motor from a game to be controlled by an Arduino board.
What I did was hook a 12V power source to a TIP122 and use analogWrite on pin 6 (using Arduino NANO) to control the input.
This used to work for a RGB led strip to control its color, but for some reason when I put a lower value than 255 the motor either doesn't run at all or makes a buzzing noise.

I don't know much about electronics and I think I'm totally doing something wrong, but I don't know what.
Hopefully any of you can send me into the right directions smiley
2  Using Arduino / General Electronics / Re: Arduino nano, disable power from USB on: November 19, 2012, 11:56:47 am
I'll be using this Arduino to control a led strip which I built into my case.
The VIN/Power is coming from my PSU, 12V which also powers the LED strip.

The reason why I want the Arduino to turn off is basically because of power consumption.
This is because my motherboard always provides the USB ports with a voltage (whether the PC is turned on or not) smiley-wink
3  Using Arduino / General Electronics / Re: Arduino nano, disable power from USB on: November 19, 2012, 04:15:00 am
Now while I'm testing it I notice that it doesn't work that well at all.
The Arduino shuts down as soon as I turn off my PC, however, when I boot my PC up again Arduino does not get regonized on my computer until I unplug the "VIN" pin and plug it back in.
Any idea how I could work around this issue? The Arduino will be plugged into my PC, so I can't disconnect the VIN pin and plug it back in after every boot.
4  Using Arduino / General Electronics / Re: Arduino nano, disable power from USB on: November 18, 2012, 05:22:56 am
You could just cut the trace coming from the USB connector.
Thanks, never thought it would have been that easy. I thought the Arduino needed the power from USB to power up the FTDI chip (:
Works like a charm!
5  Using Arduino / General Electronics / Arduino nano, disable power from USB on: November 17, 2012, 07:43:18 am
Is it possible to disable/avoid the Arduino Nano from powering by USB?

My USB ports still provide the Arduino with power when my PC is turned off (enabled in bios to charge my phone etc.).
Is there some way to avoid the Arduino from powering while the external source is not giving any power?

Thanks in advance
6  Using Arduino / Installation & Troubleshooting / Arduino on ESXi5 on: April 21, 2012, 04:27:07 pm
Is it possible to get Arduino to run on ESXi5?
When I plug in the Arduino and check dmesg it gives me the following:

Code:
2012-04-21T23:20:01.757Z cpu1:2640)<6>usb 2-2.1: new full speed USB device using uhci_hcd and address 4
2012-04-21T23:20:01.905Z cpu1:2640)<6>usb 2-2.1: New USB device found, idVendor=2341, idProduct=0001
2012-04-21T23:20:01.905Z cpu1:2640)<6>usb 2-2.1: New USB device strings: Mfr=1, Product=2, SerialNumber=220
2012-04-21T23:20:01.905Z cpu1:2640)<6>usb 2-2.1: Product: Arduino Uno
2012-04-21T23:20:01.905Z cpu1:2640)<6>usb 2-2.1: Manufacturer: Arduino (www.arduino.cc)
2012-04-21T23:20:01.908Z cpu1:2640)<6>usb 2-2.1: usbfs: registered usb0204

Echoing text to /dev/usb0204 doesn't work, whilest this works on an Ubuntu Machine.
Is there any kind of driver which I'd need to get this working?
7  Using Arduino / LEDs and Multiplexing / Re: RGB strip and ULN2003 on: April 19, 2012, 03:29:44 am
Well you still have pin 9 connected.
I did solder it all up and it works perfectly fine to control the LED strip using Arduino, thanks!
What would I need to adjust the brightness of this strip?

Do things like a PWM powered resitor exist, or would another ULN2003 on the 12V do the job?
8  Using Arduino / Programming Questions / Re: Read line from Serial on: April 08, 2012, 08:28:23 am
Quote
What would be the best method to process data which is sent like:
One character at a time.
Yes, I could save these characters in a buffer, but how will I be able to convert the buffer to a int which can be used for PWM.
9  Using Arduino / Programming Questions / Read line from Serial on: April 08, 2012, 08:21:17 am
Hello,

I want to be able to control a RGB led over serial by writing different Analog values.
The problem is that Serial.read() only returns one value a time.

What would be the best method to process data which is sent like:
r=0
g=255
b=255
10  Using Arduino / LEDs and Multiplexing / Re: RGB strip and ULN2003 on: April 03, 2012, 02:12:53 am
Quote
but what happens to PIN 9?
Nothing leave it disconnected.

This pin is designed to be used with motors that generate a back EMF, by connecting this to the +ve supply will put a reverse diode across the load. You do not have to connect it to anything.
I think I understand it now, just a quick check to make sure I'll be doing it right:


Now when I look at this scheme, I find it a bit useless indeed to use there transistors to controll one single channel. What is your advice, replacing them with 3 BD679?
11  Using Arduino / LEDs and Multiplexing / Re: RGB strip and ULN2003 on: April 02, 2012, 04:24:12 pm
Quote
will be able to mix different levels of blue by using an analogWrite
Yes the intensity of the colour will change with the PWM value you feed it. By mixing different values you will get different colours.
For an example of this see the last half of the video in my project:-
http://www.thebox.myzen.co.uk/Hardware/Hexome.html

Take that last circuit. Remove all the black wires that go to ground.
Connect pins 1 to 7 together. Do this for all three chips.
Connect pins 16 to 10 together. Do this for all three chips.

Then wire pin 8 of all chips to ground. Do not connect pin 7 to anything.
Ok, so 1-7 are all connected to the Arduino PIN, the 8th goes to GND, 10-16 to the RGB-PIN, but what happens to PIN 9?
12  Using Arduino / LEDs and Multiplexing / Re: RGB strip and ULN2003 on: April 02, 2012, 03:33:16 pm
would this create nice blue-ish color a bright Aqua-blue color
Hey I am a bloke, only girls use names like that for colours, I don't know what you would call it, try it and see.  smiley-wink
Haha, what I basicly meant is if I will be able to mix different levels of blue by using an analogWrite or if it will always be the same blue, no matter what value I put in there.


No I mean on each chip connect 15 to 10 together, and also the inputs 1 to 7 together. This makes the current flow through all the transistors for each colour, and so puts less load on the chip.
Can you give me an example of that, because I got really confused now. Do you mean something like this?
13  Using Arduino / LEDs and Multiplexing / Re: RGB strip and ULN2003 on: April 02, 2012, 02:06:09 pm
If you are going to do that then you might as well parallel those unused outputs to spread the load. That is wire pins 10 to 16 on each chip together. The data sheet says it is fine to do this.

Quote
would this create nice blue-ish color a bright Aqua-blue color
Yes.
I see I missed a word there, what I meant was: "would this create nice blue-ish color or a bright Aqua-blue color?" smiley-wink

And what do you mean by paralleling the unused outputs on each chip together, 16 is the output I'm using to PWM each color, right? Or do you mean 9-15?
14  Using Arduino / LEDs and Multiplexing / Re: RGB strip and ULN2003 on: April 02, 2012, 12:16:17 pm
Quote
do I have to connect each of the 2-8 PINs on the ULN2003 to GND
Yes otherwise there is no path to ground for the current, nor common reference for the transistors.

That circuit will work, providing your strip works by grounding the R, G & B signals. But it is a bit of a waste using three arrays only to use one transistor per array.
Might be a waste, but if it works it works smiley-wink These transistors aren't that expensive so I'm all fine with that.

I updated the scheme, you say it should work using the following?


What would happen if I put an analogWrite of 60 on the GREEN-PIN and 160 on the BLUE-PIN, would this create nice blue-ish color a bright Aqua-blue color (Asuming that the transistor doesn't work as a resistor)
15  Using Arduino / LEDs and Multiplexing / Re: RGB strip and ULN2003 on: April 02, 2012, 11:30:44 am
Quote
so 0.75A, seperated over 3 channels = 0.25A.
But added together will give 0.75A, which is too much for the chip due to power dissipation. See:-
http://www.thebox.myzen.co.uk/Tutorial/Power_Examples.html

You could use one chip per colour or a bigger darlington like a BD679 or a logic level FET.
So, the following setup should work?



Also, do I have to connect each of the 2-8 PINs on the ULN2003 to GND, or can I just leave them like this?
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