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1  Using Arduino / Project Guidance / Re: Charlieplexing on: April 14, 2014, 07:32:23 pm
Can you do that with a common ground/power?  If they are all on the same rail, or bus, or whatever you want to call it, how would you vary the LEDs oriented towards their individual pin?  IF #1 and #3 are at different brightnesses? 
2  Using Arduino / Project Guidance / Re: Charlieplexing on: April 14, 2014, 07:14:24 pm
Do you think he's doing it like one frame at a time?  If you freeze the video, the LEDs look the same every cycle.  Maybe using PWM to turn on each pair as needed, pause 20ms or whatever, move to next "frame" and turn on each LED as needed, and so on?  Sort of like stop motion animation?
3  Using Arduino / Project Guidance / Re: Charlieplexing on: April 14, 2014, 06:54:43 pm
I was thinking the same thing- but there is a common rail, and the light at full brightness goes to each LED..  So I still cant' see how it's possible. 

I was surprise he didn't have resistors either, which didn't make sense. 
4  Using Arduino / Project Guidance / Re: Charlieplexing on: April 14, 2014, 05:14:05 pm
You know, looking at the video, I don't think this is charlieplexing.  He only has two LEDs on each pin.  So how can you do the fade like that- one pin is clearly ground all the way, and two LEDs per pin.  If you pause it, the two pins are at different brightness levels. 
5  Using Arduino / Project Guidance / Charlieplexing on: April 14, 2014, 12:30:30 pm
Hi,

I just built a multicopter, and it is cool.  But to make it cooler, I wanted to install a dozen red leds an create a cylon effect.  I was reading up on charlieplexing, and it looks to be the answer with a ATTiny85 (which I have a couple).

Anyway, I was looking at the library and it looked pretty simple, but then I saw the linked video below.  He's got the LEDs dimming!  That's exactly how I want to do it, but the library has it either "HIGH" or "LOW".  So how did he do it? 

Thanks!

https://www.youtube.com/watch?v=pi2tU3ssjwk
6  Using Arduino / Project Guidance / Re: RF detector falling off for some reason on: March 28, 2014, 12:35:51 pm
Thanks for the link and info,  jremington.

LarryD, my image or his?  This circuit is all over the internet.  I take it that it is complete crap??  lol
7  Using Arduino / Project Guidance / Re: RF detector falling off for some reason on: March 28, 2014, 11:48:01 am
Okay. makes sense.  So how do I fix it?  Do you have a suggestion for a op-amp??  (I dont' know what that is, btw...)

Thanks for the reply!


Oh, by the way, this is not the original schematic.  I cut out the part that used a transistor to trigger a 555 timer.  The 555 is supposed to beep a buzzer when a cell phone is near. 

Here is the original:

8  Using Arduino / Project Guidance / Re: RF detector falling off for some reason on: March 28, 2014, 11:06:48 am
Made a call.  Nothing...  smiley-sad
9  Using Arduino / Project Guidance / Re: RF detector falling off for some reason on: March 28, 2014, 10:21:32 am
Okay, I've been doing a little reading.  Apparently a normal cell phone only sends its "Hello" packets to the cell tower periodically, so maybe I'm not picking up anything because it is on standby.  A smart phone with a running ap might broadcst constantly, but I'm using my wife's blackberry for testing, and it's not doing anything.  I guess I need to make a call and try it..
10  Using Arduino / Project Guidance / RF detector falling off for some reason on: March 28, 2014, 09:31:38 am
I am trying to build a cell phone detector.  I found several schematics online, but I liked the one below best because it has an easy output for the Arduino so I can make fancy readouts and what not.

Because I am a noob with no formal training, I figured I'd better measure the output from Pin 6 before hooking it up to my Arduino and frying it.  So I set it up on my breadboard and powered it up with my 11.4V battery. 

It worked, sort of.  About four feet away, I get zero volts on the output pin.  When I move it in towards the antenna, the voltage comes up- for about a half second, then it drops off back to zero.  The closer I get the phone to the antenna, the higher the voltage- but it still drops off back to zero if the phone doesn't move.  When I move it, the voltage comes back up, but quickly goes down. 

Clearly something is draining the signal.  What do I need to do to make the voltage constant?  I want the voltage to increase the closer the phone is to the antenna and stay there so I can give distance information with the arduino.  Any ideas??  Thanks.
11  Using Arduino / Project Guidance / Re: ATTiny85 and MOSFET on: March 26, 2014, 02:11:00 pm
SUCCESS!!!!    smiley-cool


I forgot to put the Programmer setting to "Arduino as ISP".   It works perfectly now.  Woo hoo!
12  Using Arduino / Project Guidance / Re: ATTiny85 and MOSFET on: March 26, 2014, 01:51:59 pm
Question:  Since the ATTiny chip is 1mhz, do I have to increase my delay?  I read that the compiler is set up for 16mhz and my delay might be going too fast for the voltage to trip the transistor.  Should I burn the 8mhz bootloader? 
13  Using Arduino / Project Guidance / Re: ATTiny85 and MOSFET on: March 26, 2014, 01:09:33 pm
Okay, I got it to work with the UNO, but not with the ATTiny85..

Here is what I did. 

First, I got a http://www.radioshack.com/product/index.jsp?productId=2062617TIP120 Darlington Transistor from Radio Shack.  They didn't have any N-Mosfet transistors in stock, but it looked like this one would work.  I have a protoboard shield on my Arduino Uno, and I put it on there.  I then connected my 21V battery positive to a 100ohm resistor, then to the LED +, then from the LED- to the transistor collector, then from the emitter to ground. 

I then used pin 13 to the base.  Ground to ground, and tried the standard blink program.  It worked perfectly.  I modified the blink program to do what I wanted it to do- two quick blinks and then pause.

Code:
const int ledPin =  13;      // the number of the LED pin

void setup() {
  // set the digital pin as output:
  pinMode(ledPin, OUTPUT);     
}

void loop()
{
 
    digitalWrite(ledPin, HIGH);
    delay (30);
    digitalWrite(ledPin, LOW);
    delay (90);
    digitalWrite(ledPin, HIGH);
    delay (20);
   
    digitalWrite(ledPin, LOW);
    delay (2500);
  }



So that's the code.  IT worked perfectly on the UNO. 

Next, I opened the programmer and loaded the ISP sketch.  I uploaded it to the UNO.

Then I hooked up the ATTiny85 to the UNO as follows: 
•Connect ATtiny Pin 1 (with the little dot) to Arduino Pin 10.
•Connect ATtiny Pin 5 to Arduino Pin 11.
•Connect ATtiny Pin 6 to Arduino Pin 12.
•Connect ATtiny Pin 7 to Arduino Pin 13.
•Connect the ground and 5v from the Arduino to the breadboard.
•Connect ATtiny Pin 4 to ground.
•Connect ATtiny Pin 8 to 5 volts.

I DID NOT have a 10uf cap for reset to ground, so I used a 100uf cap.

I then opened the file above (with the pin changed from 13 to 3), chose "ATTINY85 1mhz internal clock", then clicked on "Upload Using Programmer".


I hooked up the ATTiny by itself with the components and I get nothing.  I then hooked it up to a low wattage standard led (no transistor) and it still didn't work.  I checked the voltage and I have 5V going in, but nothing coming out of pin 3.  I also tried pin 0.   

I even removed the +5V coming from the voltage regulator and touche it to the base pin of the Transistor, and it worked fine- the LED comes on just like before- so the ATTiny85 is not sending 5V to the transistor.

So any ideas on what I did wrong?????  Thanks.
14  Using Arduino / Project Guidance / Re: ATTiny85 and MOSFET on: March 26, 2014, 07:43:58 am
I did not test it.  I should have. 

First, I'm not sure where you got 5V from.  I'm putting 17.25-21 volts to the LED.  The 5V is only to the Tiny85. 

I wasn't really worried about wasted heat energy because I'm just using this as a strobe.  It will only be on 1/10 of a second or so, and then off for 2-4 seconds.  Actually, I want to double flash it and then pause for 2-4 seconds.

I think I should test it with my Arduino Uno and see if it works.
15  Using Arduino / Project Guidance / Re: ATTiny85 and MOSFET on: March 25, 2014, 09:12:39 pm
I've been watching youtube videos on programming it.  I would love to get that little USB stick from sparkfun where you just plug it in and go, but I'll probably use the Arduino as the ISP and program it that way.  (If I got my terms wrong, I apologize.- I'd just copy the youtube guys)

It's this one:  http://www.parts-express.com/high-power-white-led-05w--073-024.

With fully charged batteries, the initial voltage is 4.2X5, or 21V.  But once the throttle is  up and the six motors are spinning, the voltage goes down to 3.8V X 5, or 19V.  The batteries are pretty much dead at 3.45V X 5, or 17.25V.  So there's a big swing.

Thanks for the reply!   I saw in the diagram for the transistor that the 100k resitor is going straight to ground insead of between the output pin and the transistor.  Does it matter?
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