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1  Topics / Robotics / RC Circuit and square wave on: April 07, 2014, 11:49:37 am
I would like to ask you, how does the capacitor current graph looks, if I apply a square wave signal(from 0 to 5Volts) into a RC circuit?,let's consider a duty cycle of 50%?.
Thanks in advance for you response.
2  Topics / Science and Measurement / Re: A/D converter on: April 02, 2014, 04:57:49 am
??? what do you mean Jantje?  smiley-confuse  I am trying to read a pot but I want to understand A/D conversion first. My next step is to study electronics in the future, but many people told me that using arduino I'm just wasting my time smiley-sad and I have to learn embedded C language to work with PIC or AVR microcontrollers.
btw thanks for your opinion  smiley-sad
3  Topics / Science and Measurement / Re: A/D converter on: April 02, 2014, 03:59:51 am
Ok guys, thanks a lot for your answers ... but I think you didn't give a quite clear answer .... I am trying to do a project for my secondary school and I dont really understand what you wrote! ..... Could you response to this please :

Hello,
I would like to ask you very kindly about 10bit arduino converter. If I am using 2V as reference voltage then to calculate its resolution I can apply the following formula Vref/(2^N-1) or Vref/(2^N) ??? which one is correct??? . Moreover, If the converter give 512, to calculate the corresponding voltage value I can use this formula 512*(Vref/1023) and if it is giving 256 then 256*(Vref/1023) and so on ???? in other words is it correct to use 1023 or 1024 for 10 bit converter???

Thank you in advance for your response.

4  Topics / Robotics / A/D Arduino converter on: April 02, 2014, 02:31:29 am
Hello,
I would like to ask you very kindly about 10bit arduino converter. If I am using 2V as reference voltage then to calculate its resolution I can apply the following formula Vref/(2^N-1) or Vref/(2^N) ??? which one is correct??? . Moreover, If the converter give 512, to calculate the corresponding voltage value I can use this formula 512*(Vref/1023) and if it is giving 256 then 256*(Vref/1023) and so on ???? in other words is it correct to use 1023 or 1024 for 10 bit converter???
Thank you in advance for your response. 
5  Topics / Science and Measurement / A/D converter on: April 01, 2014, 07:00:05 am
I would like to ask you very kindly How can I correctly calculate the resolution for a A/D converter (10bits) ? Why many people is using the following formula Vref/1024  and other Vref/(1024-1)  ???? This is very confusing !
Thank you in advance for a suitable response.
6  Topics / Robotics / Re: How to eliminate the offset of a signal on: June 28, 2013, 02:06:19 pm
Hello,
I have tried capacitors but, it is not working. I dont really understand why! I have used 1uF and10uF electrolitic capacitors, but it is not solving the problem, the signal is still oscillating around 1.4volts.
Could you explain why the condensator is not solving that problem? . I have connected the signal to the capacitor positive leg and the other to the ground? is it correct ? or how should I connect the capacitor???
Thank you in advance for your response.
Best regards.
7  Topics / Robotics / How to eliminate the offset of a signal on: June 26, 2013, 09:47:55 am
Hello,
I would like to ask you very kindly how I can eliminate the offset of a signal. My signal is oscillating around 1.4 volts so the maximal displacement of my signal is 1.45 volts and the minimal 1.35volts. I need that signal oscillating around zero so maximal displacement 0.05 volts and minimal -0.05. In other words +/- 0.05 volts. How Can I do that ? Could you help me with this problem please?.
Thank you in advance for your response.
Have a nice day.
8  Topics / Robotics / op-amp:Gain Tunning Problem on: June 14, 2013, 12:04:47 pm
Hello,
I would like to ask you very kindly the following question:
I'm trying to make an active low pass filter, It consists of 3 parts. First one is to develop a bipolar symmetric source in order to connect a op-amp ua741, the second is to implement an active low pass filter using that op-amp. Up to this point everything is going well. But when I connect the second op-amp and put the suitable resistors. So there is starting a problem with the bipolar symmetric source, which is not symmetric anymore. So, I get more negative voltage than positive and I don't know why? Can somebody explain me why?
Thank you in advance for your response.
Best regards
9  Topics / Robotics / Reading analog input using Arduino Motor Shield on: April 10, 2013, 11:39:50 am
Hi there!
I would like to ask you if it is possible to read an analog input using arduino motor shield while a DC motor is going forward and backward. I have a big problem when I'm trying to do this because a delay of 90ms is necessary in order to move the DC motor and I need to sense an analog input with a sampling time of Ts=0.01s. Could you advice me please?
Thank you!
10  Topics / Robotics / Re: How to read +/- 4 volts using Arduino on: March 22, 2013, 09:05:07 am
Thanks Pito !.
11  Topics / Robotics / How to read +/- 4 volts using Arduino on: March 20, 2013, 12:25:18 pm
Hello:
I want to ask you if it is possible to read a voltage signal +/- 4 volts using Arduino. It is a sinus signal, which is going from +4volts to -4volts and vice versa.
Could you explain me how to do that step by step.
Thank you very much for your help.
12  Topics / Robotics / Re: How to change 5 DC volts from Arduino into +/- 5 volts on: February 09, 2013, 11:08:51 am
Hi my friend:
what do you mean by negative pin ? is it GND ? , I have tried tuning a negative value for analogWrite --- PWM pin 9; but it just can send a maximum voltage around 4.96 volts. In other words, It is not possible to get a negative voltage directly from arduino. I think it is necessary to design an external circuit to obtain that value. But I have no idea about how to do it.
Waiting for responses smiley-grin
thanks for your help smiley
13  Topics / Robotics / Re: How to change 5 DC volts from Arduino into +/- 5 volts on: February 09, 2013, 09:39:25 am
Hello my friend:
So the waveform can be for example v=5sin(2*pi*frequency), frequency=3Hz.
Using arduino is I think impossible to get an oscillating voltage between +/- 5 volts. Because the  arduino output voltage is from 0 to 5 volts.
Any data acquisition card has that possibility but is veeery expensive. I can't pay that smiley-sad
How can I resolve my problem using arduino?
or there is not solution?
thank you for your help my friend.
14  Topics / Robotics / Re: How to change 5 DC volts from Arduino into +/- 5 volts on: February 09, 2013, 09:09:00 am
Thank you for your response. So, the problem I have is as follows.
I have an input voltage, for example 5 DCV, which will be applied for 2 minutes. So I would like to obtain an output voltage oscillating between -5 and +5 volts. How can I get that ? is it possible ?
I have no experience with electronics, but I need to do that for my school project.
Thank you.
15  Topics / Robotics / How to change 5 DC volts from Arduino into +/- 5 volts on: February 09, 2013, 07:33:32 am
Hi everyone:
I would like to ask you how is it possible to change the output voltage from arduino (5 DCV) into a +/- 5 DCV?
Thank you for your help.
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