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226  Using Arduino / Project Guidance / Re: ideas needed on: September 15, 2011, 07:36:10 pm
make some ferrofluid, very easy but pricey, then a glass enclosure for it , then inside the glass along with the ferrofluid add something with a nice spiral like a meat grinder,  then under that something that can generate a magnetic flux,preferably a variable flux so you can control its intensity , then connect that to the spiral thing, oh it has to be able to be magnetized , so no plastic, anywho then under everything put like a turntable or some how make it turn si i looks nice, all this with an arduino and you get something like this
227  Using Arduino / General Electronics / Re: Analog pin problems on: September 15, 2011, 04:38:43 pm
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It turns out to be pretty easy to measure source (or output) impedance.  You need only a variable resistor (like a pot) and a volt/ohms meter.  Measure the unloaded output voltage from the mystery source. Then attach a variable load (your pot) across the output and increase the load until it is 1/2 the open circuit (unloaded) voltage which you previously measured. Then disconnect the pot and measure the resistance. That resistance is equal to your source impedance. 

The principle is that you are forming a voltage divider. The "top" resistor in the divider is the mystery source impedance, and the "bottom" resistor is your pot.  When the voltage is 1/2, then the two resistors are of equal value.

Of course, if you are measuring something at the extreme ends of the spectrum, conventional parts and techniques don't apply. So measuring the source impedance of a guitar pickup or a car battery can't be done using this simple scheme.



 if i could pay you for posting that i would, thanks for that.
228  Using Arduino / General Electronics / Re: Analog pin problems on: September 15, 2011, 10:32:15 am
according to my book :

Quote
when output impedance is small a relatively large output current can be drawn from a devices output without significant drop in in output voltage.

When the output impedance is large a relatively small output current can be drawn from the output of a device before voltage at the output drops substantially.

A rule of thumb for efficient signal transfer is to have an output impedance that is at least 1/10 of the loads input impedance to which it is attached.

Now i do not know what half of that means or how one would go about measuring this impedance, it seems like in a very simple simple way its the resistance "outward" being that high impedance lowers current output.. so yeah maybe you can decipher that better then i.


UPDATE: dam! i think it just clicked, so if i have  a million things  in a circuit all taking a chunk out of its  current  then furthermore if i try to output something it will be at a very low current since it is all being used up... interesting
229  Community / Bar Sport / Re: Need for an IP seeking cruise missile or good manners don't cost nuthin'! on: September 14, 2011, 01:15:27 am
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I've found this forum to be heads and shoulders above most I have come across, as far as positive and helpful posters.

agreed!


funny i agree with the initial post but then i saw the quality of and how quickly you can get answers, GOOD answers, from fellow members so i figure i stop being a baby and just let the little "are you an idiot or something" remarks slide... i never really recieved a remark like that , just subtle condescending remarks preceding a very insightful answer.
230  Using Arduino / Microcontrollers / simultaneously running multiple sketches..with 1 board on: September 14, 2011, 12:52:32 am
what woulld you do with a board that could emulate a cpu, or a microcontroller or a vga graphics controller or digital synthesizer ...all at the same time?
with 54 i/o pins / 16 analog inputs ?

i was browsing kickstarters and came across a board like so


...its based off of a "multicore capable" Xilinx Spartan FPGA (Field Programmable Gate Array) ..w/e all that means smiley
231  Using Arduino / Microcontrollers / Re: NXP's Cortext M-serires uC's on: September 13, 2011, 12:14:48 pm
yes that is always true with all uC , Arduinos community is far Superior.

I did find a nice little development board about 10 dollars more expensive then a "stock"  Uno , and it comes with a library to quickly get started interfacing
such as serial communication reading and writing i/o's 

http://adafruit.com/products/281

I have only scratched the surface of the arduino world though i should probably try to learn this inside and out before going on to more complex not so user friendly processors.
232  Using Arduino / Microcontrollers / NXP's Cortext M-serires uC's on: September 13, 2011, 11:40:35 am
can anyone give me some insight as to how or if these compare to the Atmega line. I have watched some videos on the Cortex's but with so much technical talk about the core architecture i cannot understand it all, i could best understand it when in comparance to something i am more familiar with, hence the Arduino,
so are these Cortex's faster more powerfull processors , is it the same principle in the sense of  .. Program it, get input, send output, serial comm. pwm ... etc... ?
because i was also looking at TI's microcontrollers the Mps..something  ... and ,compared to the Arduino programming ide and language,   that thing is not that pretty or straight forward to program, at least not very welcoming to novices.. in my opinion
233  Using Arduino / Project Guidance / Re: Voltage Divider equation.. Is my bleeder R and bleeder I on: September 12, 2011, 10:46:13 pm
i mean i am not using this for a project or  anything i just wanted to put the theory to work and see it for my self
234  Using Arduino / Project Guidance / Re: Voltage Divider equation.. Is my bleeder R and bleeder I on: September 12, 2011, 10:38:54 pm
obviously i am using slightly different resistor values but my output voltage is no where near what it should be according to the math, which i am sure i messed up somewhere along the lines

 Just realizzed i posted this in the wrong section, i am so use to just coming to this section sorryy.
235  Using Arduino / Project Guidance / Voltage Divider equation.. Is my bleeder R and bleeder I on: September 12, 2011, 10:33:39 pm
Some insight here would be helpful because i am not getting the desired results..
According to this Book i am reading...  Practical Electronics for Inventors...which is plagued with errors, which i did not find out until i purchased it and wrote in it.. but anyhow..
!0% Rule
Using there method to find the Value of R1 and R2 in a voltage divider circuit I first have to find the Bleeder current
which is the current through R2 and which is also 10% of the output current i want [i(load)]

so If i have a 5v power source and i want my output to be 3v at 25mA

i have to find 10% of the load/ output current  i want
i2 (bleeder current )   =  .1 x 25ma = 2.5 mA ... okay we will save this for later..

next it says to determine the load resistance, and that the bleeder resistance is 10 times the load resistance..

so being that i want 3v @ 25mA

R(load) = 3v / .025A = 120ohms  ---> 120 x 10 = 1,200ohms
so R2(bleeder) = 1200 ohm

now to find the current i1 which is the one going through R1   i just add the bleeder current and the load current so : 2.5mA(i2)  + 25mA (load/output Current)  = 27.5 mA
 so to find R1 i go back to ohms law now that i have the current for i1
 R1 = (5Vin - 3Vout)   / .027A(i1)  == 74ohms
so R1 = 74ohm and R2 = 1200 ohms

and i should get an output of 3v and 25ma  
but this is not the case smiley-sad

my multimeter show .221 volts
236  Using Arduino / Project Guidance / Re: Arduino positioning on: September 12, 2011, 03:45:44 pm
if you look at this video
 

they use some QR code type of thing and have an application running on a computer that looks for that Code/Picture and the robot navigates to it and waters the different plants accordingly to what code it has,
you could translate this into some sort of circular scanning camera  looking for the arduinos in its vicinity , and you can mount some sort of QR code on each of the surrounding arduinos to be identified.. i dont know if this makes any sense but watch the video it might help understand what i am saying.....

its a tracking system , just that you would place the individual markers on the surrounding arduinos and the tracking application would be the middle arduino or the "seeker" ....

of course with Arduinos alone this is not possible,  at least i dont know so  do not take my word for it  
237  Using Arduino / Programming Questions / Re: HOW to visually represent PWM ?? on: September 05, 2011, 08:10:09 am
it would be using just the arduino pwm pin to pwm from 0 - 5 ,  assuming i would not exceed the pins  max current ratings..


 well actually i think i am wrong, because if use an arduino pwm pin and try to use it as a variable power supply on something with a max rating of 1 volt , i will damage it because with pwm i am never really giving it a variable voltage , just pulses of 5v? correct
238  Using Arduino / Programming Questions / Re: HOW to visually represent PWM ?? on: September 05, 2011, 07:59:05 am
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The "average" voltage is then (duty cycle/255) * Vcc.
thanks for that one paul

and thanks mr gumpy i will take a look at that
...


so could one create lets say a small 5v variable power supply using the arduino., of course along with all the right components and pulse width modulation ?
it might not be the best practical way to do it , when you could use something with no code like a  potentiometer  , but it would work  i might have to read grumpy's power tutorials for that one huh
239  Using Arduino / Programming Questions / HOW to visually represent PWM ?? on: September 05, 2011, 06:43:53 am
hey fellas how would i go about, being there is a way, to represent the average value of voltage being outputted by a pwm pin ; but not the wave like this

because  i do not have an oscilloscope , i just want to send the value out through serial ;
so if i have something like analogWrite 35 i would send out something like 2.45 volts ... or even easier is there a formula that i could just implement to figure out the average voltage.
Thanks.
240  Using Arduino / Project Guidance / Re: Another Quad copter with a twist on: September 04, 2011, 06:44:29 am
Aeroquad is an Arduino based quad copter and they have whats called ArduPilot (which is just the stabilizing software) and  other software which lets you plot i think over 100 pionts on a  map and the gps on the copter will fly that exact route and then return home so yes something like that is possible.. however you wish to control it real time thats a bit trickier i suppose gsm could do the trick, then i goes back to what the use said about weight vs flight time you might want to check out how the Aeroquad people do it
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