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16  Using Arduino / Motors, Mechanics, and Power / Re: Controlling Two 12v Fans off Arduino using one Power Adapter on: April 13, 2014, 02:24:14 pm
What do you think of the RFP30N06LE (see attached) as  a replacement ?

If you have them, they're acceptable.
I would suggest an NPN "switch", assuming there are a couple of NPNs and some resistors in the house, as in the attachment.
Anyone could dispute the 22K, I suppose - go for a lower value - but it would be effective.
17  Using Arduino / Motors, Mechanics, and Power / Re: Controlling Two 12v Fans off Arduino using one Power Adapter on: April 13, 2014, 02:10:54 pm
Again?  When it's not TIP darlingtons then it's IRF HEXFETs.  Aaack!

An IRF530 and  5V for Gate voltage isn't a match made in heaven, is it?
Who thinks that 5V is enough to get those into solid conduction?
18  Using Arduino / LEDs and Multiplexing / Re: Breathing LED controlled by temperature sensor (NEED HELP!!) on: April 13, 2014, 01:41:19 pm
Sorry, but why x/17?
It doesn't work

Because from my experience of it, only values of x less than 15 give a good result, higher values are too fast.
So the range, I believe, should be limited to 0 to 15  not 0 to 255.
255 / 17 = 15
If you can reconfigure the map expression for that -- then by all means.
It was easier for me to divide that by 17, cheap and easy.

Does my demo sketch in Reply #9 effect a fade in/out somewhat as you expect?
It won't change, it just stays at that one "speed", but it verifies the fading aspect anyway.
Doesn't even that much "work"?  [I think it does here - I can youtube evidence of that if necessary.]

And I don't know from your "wave", let's see your "transistor circuit", please.

I guess I am being unreasonable.
19  Using Arduino / General Electronics / Re: somebody please explain this? sketch attached on: April 13, 2014, 12:56:48 pm
In both of those examples, as long as the opto input is on then the triac will be on.
20  Using Arduino / General Electronics / Re: can anybody tell me the gain of this transistor for 0.15 amp collector current? on: April 13, 2014, 12:54:06 pm
For one thing, you are making the "design" beta dependent.
21  Using Arduino / LEDs and Multiplexing / Re: Breathing LED controlled by temperature sensor (NEED HELP!!) on: April 13, 2014, 12:51:46 pm
Does running my simulation example [above] result what you expect ?
If not, could you sketch out your transistor circuit?
(Skip the verbal, do the schematic or make a diagram.)

Code:
const int transistorPin = 9;
int tempPin = 0;
int tempReading;
int x;
void setup()
{
  pinMode (transistorPin, OUTPUT);
  Serial.begin(9600);
}

void loop()
{
  tempReading=analogRead(tempPin);
  x=map(tempReading,150,170,1,5);
  x = x / 17  // *NEW* IF preceding line results 0 < x < 255 then, here, 0 < x < 15
  float val = (exp(sin(millis()/1500.0*x*PI)) - 0.36787944)*108.0;
  analogWrite(transistorPin, val);
}


22  Using Arduino / Project Guidance / Re: Led Cube Electrical Scheme on: April 13, 2014, 10:26:08 am
http://forum.arduino.cc/index.php?topic=232838.0
23  Using Arduino / LEDs and Multiplexing / Re: Breathing LED controlled by temperature sensor (NEED HELP!!) on: April 13, 2014, 10:13:58 am
OK, cool

WIth this modified version of the sketch
Code:
const int transistorPin = 9;
int tempPin = 0;
int tempReading;
int x;
void setup()
{
  pinMode(transistorPin, OUTPUT);
}

void loop()
{
  //tempReading=analogRead(tempPin);//temperature reading
  //x=map(tempReading,150,170,1,5);//map the reading to change the frequency
  //Serial.println(x);
  x = 1;
  float val = (exp(sin(millis()/1500.0*x*PI)) - 0.36787944)*108.0;//the function of breathing led
  analogWrite(transistorPin, val);
}
there's a pulsating effect
BUT
only for values of x < 15 or so.
24  Using Arduino / LEDs and Multiplexing / Re: Breathing LED controlled by temperature sensor (NEED HELP!!) on: April 13, 2014, 09:37:51 am
So, if I used that sketch with an ordinary LED, but made tempReading a const, it'd sit there fading in/out?
Can you suggest a good value to plug in?
25  Using Arduino / LEDs and Multiplexing / Re: Breathing LED controlled by temperature sensor (NEED HELP!!) on: April 13, 2014, 08:46:37 am
and what transistor?

Transistor?

How do I take a pause after sampling and analogWriting at the end of the loop? 

Code:
#include <math.h>

const int transistorPin = 9;
int tempPin = 0;
int tempReading;
int x;
void setup()
{
  pinMode(9, OUTPUT);
  Serial.begin(9600);
}

void loop()
{
  tempReading=analogRead(tempPin);//temperature reading
  x=map(tempReading,150,170,1,5);//map the reading to change the frequency
  Serial.println(x);
  float val = (exp(sin(millis()/1500.0*x*PI)) - 0.36787944)*108.0;//the function of breathing led
  Serial.println(val);
  analogWrite(transistorPin, val);
  delay(500);  //  <<<< a pause
}

Stll, though, what is the "breathing" effect here?
26  Using Arduino / General Electronics / Re: Transistor's base voltage.. on: April 13, 2014, 08:39:54 am
cj,
Are you off your meds again?
27  Using Arduino / General Electronics / Re: Maximizing RFID Reader Operating Range on: April 13, 2014, 08:38:44 am
I have connected an RFID reader to my Arduino Pro Mini.  Initially, I had connected a 9V 650 mA adapter to the Arduino raw pin.  However, when I connected a 9V 1A adapter, the read range of the RFID reader increased. 

Also, could you elaborate please?  I'd be happy to provide more details.

Maybe the 650mA supply is a dud?

What I'm taking from this is that you're running the RFID from the ProMini 5V pin?
When you had the ProMini running off a "9V 1A" the RFID did better than when using a "9V 650mA" supply.
Now that I see the data sheet, Page 2 (table 1) informs us that it can run from a wide supply range, 5-15V.
So, why not run it from your "9V" supply directly?

Perhaps you could dispel all doubt and attach or link to a sketch of your hook-up diagram of what you have going?
Or take a good quality picture with everything in shot?

28  Using Arduino / General Electronics / Re: Transistor's base voltage.. on: April 13, 2014, 08:26:53 am

Give them an inch and they'll take a mile.
There's that VCBO spec, too


29  Using Arduino / General Electronics / Re: Transistor's base voltage.. on: April 13, 2014, 08:17:03 am
VBE vs. VEB

What's in a name?  A lot.
30  Using Arduino / General Electronics / Re: Maximizing RFID Reader Operating Range on: April 12, 2014, 07:11:48 pm
Also, here is the spec sheet of the RFID reader...

Where?


Still, from your description, something seems amiss.
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