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1  Using Arduino / Motors, Mechanics, and Power / Re: fan3122 mosfet driver on: March 12, 2012, 10:16:11 pm
Thanks for the reply I wasn't sure what to make of the .3 and so far i haven't got the driver to turn on the mosfets. I think I have found the problem though a loose wire going to my circuit board.
2  Using Arduino / Motors, Mechanics, and Power / fan3122 mosfet driver on: March 12, 2012, 09:26:55 pm
Ok, here is the deal i think i made a mistake in my component selection. I bought a fan3122 mosfet driver to use with my arduino. I didn't look at the data sheet very carefully. Looking at it again it looks like the max input pin voltage is .3 volts. My question is well the chip work with the arduino's pulse width modulation or did i get the wrong mosfet driver? If I did get the wrong mosfet driver what could I get instead that has the same layout as the fan3122? I already put together most of my circuit board and I don't want to have to start over.

data sheet link http://www.fairchildsemi.com/ds/FA/FAN3121C.pdf
3  Using Arduino / Sensors / Re: non-arduino speed sensor on: March 04, 2012, 09:54:29 am
Thanks again everyone for the help I finally got it working. Turns out it was an open collector and I need to use a pull up resistor to get things working. Right now i'm the pulse in function for my code.
4  Using Arduino / Sensors / Re: non-arduino speed sensor on: February 28, 2012, 11:49:09 pm
Robtillaart, thank you for the example code.

Johnwasser, I think the signal is a square wave that goes from 0 volts to 12 volts. I don't think it is an "open collector". So my problem would be that the arduino has a max input of 5 volts and my sensor is sending it 12 volts? 
5  Using Arduino / Sensors / Re: non-arduino speed sensor on: February 27, 2012, 08:36:32 pm
I think i may have found the problem. Would I a pull down resistor? My test speed was 5-10mph. The sensor was on and working.  Below is the code i have tried with the sensor. Nothing fancy just trying to see if i'm getting an input.

Code:
int inputPin=4;
long gpsPulse;

void setup() {
Serial.begin(9600);
pinMode(inputPin, INPUT);
}

void loop() {
  gpsPulse=pulseIn(inputPin,HIGH);
    if(gpsPulse>0){
    Serial.println(gpsPulse);
   delay(500);
  }
}
6  Using Arduino / Sensors / non-arduino speed sensor on: February 26, 2012, 10:42:56 pm
I have a gps speed sensor that outputs a square wave proportional to the speed the sensor is moving. The gps puts out a 50% duty cycle square wave at 10.115 Hz/MPH. I've tried using pulseIn() to measure the square wave length but it keeps coming back as zero. What am i doing wrong? I don't have an example of my code on this computer but i can post it later if it helps. Right now all i'm trying to do is get the timing of the square wave and go from there.

Here is a link to the spec sheet http://www.micro-trak.com/PDF/Astro.pdf
7  Using Arduino / Motors, Mechanics, and Power / Re: pwm for a 20 amp motor on: February 20, 2012, 01:28:26 pm
Thanks for the example diode just want to make sure we were on the same page so to speak. What amount of waste heat is reasonable for a fanless design in a metal enclosure?
8  Using Arduino / Motors, Mechanics, and Power / Re: pwm for a 20 amp motor on: February 19, 2012, 10:51:16 pm
Thanks for the info on the mosfet driver chip I hadn't read anything on that. So I take it that I want no more than about 2 watts of waste heat per mosfet with a good heat sink? Do you have a certain diode in mind I've read a lot on the mosfet but not too much on the diodes.
9  Using Arduino / Motors, Mechanics, and Power / pwm for a 20 amp motor on: February 19, 2012, 08:43:56 pm
I'm looking for some circuit designs that would work to drive a 12 volt 20 amp dc pump. Do i just need the right mosfet and diode or do i need a more complex circuit? I've done a fair amount of reading on pwm and dc motors but most of the circuits I have found have been for loads under 10 amps. I also need a fanless design because the circuit will be used in a dusty environment.
10  Using Arduino / Installation & Troubleshooting / Re: Pin overvoltage on: February 19, 2012, 09:57:48 am

If you're using the standard jumper wires with male pin on the end to make connections to the
board headers, you might take a bunch of them, cut them in half, and solder a small value resistor
in the leads, 220 to 330 ohms. Put some tape or tubing over the connections to isolate the bare
connections. Goes a long way towards protecting I/O pins from overvoltage and short-circuits.


I'll keep that in mind. I just happened to make a dumb wiring mistake.
11  Using Arduino / Installation & Troubleshooting / Re: Pin overvoltage on: February 19, 2012, 09:51:22 am
Remove the ATmega328.  If you can reprogram the ATmega8u2 then the rest of the board is salvageable.
If you short one of the IO pins for just a short while what are the changes that the rest of the board has been damaged? I haven't bought a new ATmega8u2 chip yet.
12  Using Arduino / Installation & Troubleshooting / Pin overvoltage on: February 19, 2012, 12:11:34 am
I made a mistake and put 12 voltages dc right to one of the IO pins on an Arduino Uno. My question is did i damage the whole board or do i just need got get a new atmel chip. The 12 volts was only applied for a a second or so max. The usb controller still shows up when i plug my Arduino board into my computer but goes right to DFU mode.
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