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16  Using Arduino / Motors, Mechanics, and Power / Re: PWM for 3-phase Inverter on: July 19, 2014, 08:40:03 pm
Is this 3-phase inverter for driving a motor,   or to create a three phase power supply for something other than a motor ?
17  Using Arduino / Motors, Mechanics, and Power / Re: How to: 9-24V Solenoid w/ PWM on Arduino Safetly on: July 19, 2014, 08:35:08 pm
You will need a circuit with a transistor or relay to turn on the current to the solenoid coil.
18  Using Arduino / General Electronics / Re: PWM 12V 150Amps output signal using arduino is it possible ???? on: July 19, 2014, 08:31:53 pm
I do have PWM modulator run on car battery 12 and output 150 amps continuously 

So,   have you already actually done this ?

If you have already got it to work,   then what exactly is your question ?
19  Using Arduino / General Electronics / Re: PWM 12V 150Amps output signal using arduino is it possible ???? on: July 19, 2014, 08:28:52 pm
You will need to check whether PWM  will even work for the electrolysis of water.
20  Using Arduino / Sensors / Re: Problem with HMC5883L.. help on: July 19, 2014, 08:19:15 pm
The scaling and offset of the different axes of those HMC5883L's isn't all that good.

The ones I have,  will happily tell you that the angle between north and east is about 30 degrees.   All of mine would have been up to 23 degrees off direction.  Although like a broken clock which is right twice a day,   there are a couple of directions where it coincidentally happens to be correct.

You do need to calibrate them.

Now,   the question of whether the calibration would change so much in a few weeks,  is a different question.

I use one which was calibrated about 18 months ago,   and it is still right ( after applying the corrections ) today.  I have not personally experienced the calibration change which you have described.

21  Using Arduino / Programming Questions / Re: #define, int or const int on: July 19, 2014, 07:35:50 am
This nonsense that you wrote:

#define ABC 123.456 * 789
#define ABC_DEF 654.321

void setup()
  Serial.println(123.456 * 789_DEF);

void loop(){}

doesn't even compile !

sketch_jul19a.ino:9:28: error: invalid suffix "_DEF" on integer constant

It is clowns like you that make it very difficult for people over 40 to get a job.
22  Using Arduino / Sensors / Re: Load Cell Help on: July 19, 2014, 07:03:32 am
//when button is pressed open valve to feed
    //reads load cell value puts value in Vin
  vin = load ;

This bit of code seems to be totally meaningless.

You are going to need to develop some basic competency with understanding C/C++ code,   you won't succeed by randomly sticking together bits of code that you copy from somewhere with no understanding of it.

I am amazed you actually got a load cell to work.
23  Using Arduino / Sensors / Re: Measure decibels using a piezo on: July 19, 2014, 06:56:41 am
Actually,  it is not a "professional sound sensor" that you need.   Any useful microphone ,  even quite cheap one,  is capable of converting the "sound pressure"  into voltage.  That's what microphones do.

It is reasonably straightforward to build a circuit with a microphone,  an amplifier with a stable gain,  an ADC and a program on the arduino to capture the peak voltage level of each sound oscillation,  which corresponds to the fluctuations of the air pressure due to the sound waves.

The problem then,  is calibration.

You could then borrow a decibel meter from somewhere,   make a whole series of experiments where you measure the voltage level with your device,  and the decibels with the sound meter.    Provided you can then establish a systematic and reproducible correlation between the two sets of readings,   there is your device calibration done.

The main "catch" with this,  is going to be the capability of the microphone and gain response of your circuit at very high and low frequencies.
24  Using Arduino / Sensors / Re: Measure decibels using a piezo on: July 19, 2014, 06:43:03 am
It is easy to get a microphone,  amplify the sound signal,   capture the peak levels  and drive some kind of led bar graph display.

Actually calibrating this to correspond accurately to decibels over a range of loudness and frequency is a non-trivial problem which you are not going to be able to accomplish without professional equipment.
25  Using Arduino / Sensors / Re: Default DS18S20 example returns perplexing results on: July 19, 2014, 06:35:03 am
The 9 byte message you are getting from that device has a suspiciously large number of FF's in it.

That tends to suggest to me that the electrical characteristics of your circuit are unsuitable somehow.
26  Using Arduino / Sensors / Re: bmp180 library on: July 19, 2014, 06:21:46 am
Can we help you with this problem in one thread, please ?   Choose one,  and post there.
27  Using Arduino / Sensors / Re: bmp180 library on: July 19, 2014, 06:20:32 am
If you are reading 1500 mbar then your sensor is broken.
28  Using Arduino / Sensors / Re: Barometric Presure sensor BMP180 on: July 19, 2014, 06:18:09 am
what is the code of your sketch ?

"provided altitude"  is something that your code has in it,  it is not coming from the device.
29  Using Arduino / Sensors / Re: GPS Module not working. on: July 19, 2014, 06:08:27 am
try this

void loop()
  while(uart_gps.available())     // While there is data on the RX pin...
      char c =;    // load the data into a variable...
      Serial.print(c) ;

If you do this,   you will see the GPS output directly.
This will confirm the GPS is running and it is outputting NMEA data.
Google "NMEA gps"  to learn what that means.

The GPS has to be outdoors  or next to a large window to work.

If you are indoors,  the GPS will still output data,  which will effective mean that it has not
figured out where yet.

If you use the code I just posted,  you will see that output.

The "problem" with the example code you posted earlier,   is that the tinygps routine won't tell
you anything at all until it gets a location.   It will appear to do nothing at all.

30  Using Arduino / General Electronics / Re: Difference in setup between AC and DC on: July 19, 2014, 12:04:06 am
How does a solenoid even work with A/C ?   Isn't the plunger going to attempt to buzz in and out at 120 Hz ?
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