Hi everyone,

I am trying to figure out how to connect VU meter leds on speakers to give visibility to the audio signal that they will play.

This is as part of an installation and, because of its location and design, it could be a little complicated. The set up is out side, so everything needs to be waterproof, while the amps (that will power all the speakers) will be in another place covered.. so there will be long wires going all the way to the speakers, and I would like to avoid adding other cables running from the amp to the speakers, so I was hoping to use just the power running on the speakers cable. We found this kits: http://store.qkits.com/moreinfo.cfm/FA102, but they are pretty expensive and would be good to find something in europe..

Any solutions or ideas would be much appreciated! Thanks a lot..

Hello,

I am trying to figure out the best way to put a sensor on a bathtub tap mixer so to use the tap a knob to control analog values.
The tap will not be used for water anymore, so don't worry about waterproof problems.. I am sure there is an easy way to do this, but my trials and mistakes didn't really help. Any ideas?

Thanks

Hi everyone,

I just ordered some Hall Effect sensors (ALLEGRO MICROSYSTEMS A1302KUA-T) but I am not sure whether they can just act as on-off switch or also as priximity sensors. I need to measure the distance of a moving piece of metal (where i would screw a magnet) while it is moving.


ps: if you want to know what's this is all about. I am just trying to figure out a way to attach a sensor to a bathtub mixer.. after trying (and failing) the potentiometer way i thought it could work measuring the moving distance of the screw which is inside the tap, the one that change the water pressure inside..

thanks a lot!

I got lots, but I will use the correct number for each arduino if you could tell me exactly which resistors and how many of them..

My guess is 10 leds (200mA) with 90 ohm resistors if powered by 5volts

or 300 ohm resistors if powered by 9 volts adapter, right?

Hello,

for a quick project I need to use these leds (http://www.sparkfun.com/products/9850) hooked up with the 12 PWM mega pins.

the leds are 20mA 3.2 Volt

the sketch will fade all the leds at the same time using various durations for each of them

What kind of resistors I need to use? Please I need to buy them tomorrow, let me know if you have any idea..

I tried without resistors and they all work fine, but the Mega chip is burning hot so I guess I need to do something different. I have no time to use IC chips at the moment..

thanks

200/330 R? What's R stands for? I always used ohm.. ? sorryyyy
if you can tell me i'll go buy them tomorrow morning. thanks a lot

Thanks Mike

So i'll go for 2k resistors between the arduino pin and the + of the led, right?

Also as Simpson was saying "a wise amount" for chip would be 10? What would happen with 12? (2-14 PWM)

I have no idea what happened, but all this thing began to be too complicate for me. Chips blowed up, wires are playing up, breadboard always do different things.. I am gave up for the moment and just use the pwm avaibables on 2 arduino mega i borrowed for this week. so i should be able to use 24 leds right? It's fine for now, then I'll get some time do resolder better everything.

So, quoting something from the first page of this topic:

You could... also drive them normally, but you'll have to be very sure your programm doesn't turn on too many leds at the same time. With 800mA flowing, the possibility of smelling magic smoke is quite high. 1 mistake while writing/testing the program can be enough to need a new Mega. Internally the mega uses different ports up to 8 pins per port, you'll also need to check the datasheet to see what a port can handle max.

I am gonna try this easy way. Do I need resistors between the leds (20mA, 3.2 V drop) and the arduino pin, or not?

thanks

where should i put the capacitors? is 47 better then 100 then? i've got both
i tried:

arduino 5v > capitor > circuit
arduino gnd > capitor (short leg) > circuit

but doesn't seem to change much

Nice article. I'll try understand it all.. I wish you were our lecturer or similar!! 

Have you used any of these solutions for the tlc chip in particular?

I tried with the 9 volts adapter but it's the same. It is a 9v, 0.6 A one so it might be a current problem for real... I'll go and check if i have a 1A adapter, but i doubt it, will have to buy one.

Yes I would like to have a pc here, but I just got a macbook with me..

Do you think I could use a 9 volta adapter which I used before for arduino projects? I think it should be fine cause it will power the board and it will give the right 5 volts to the chip using the 5 volt arduino power pin. Is that right?

Also, is there anyway I can give more power to the leds? They don't seem so bright as they were advertised on sparkfun (http://www.sparkfun.com/products/9850). Is there anyway to give them indepent power? That would be great..

thanks

Yes, apparentely it works without deleting it now. All good then!

I tried quickly this morning, and when I added the other 16 leds for the second chip they all began to flicker and tremble.. Could it be a current problem? Did it happen to you guys?

I attach my code, my brother helped me out with it:

Code:

#include "Tlc5940.h"
 
  const float duePiMillis = 0.00628318531;      // Two time P divided by 1000
  const int maxValue = 2000;                    // Maximum value for the LED
  const int numOfChannels = 32;                  // Number of active channels

  // Array representing the duration of the cycles in seconds - don't need to reduce the number of channels!
  const float cycleDuration[] = {2, 4, 7, 10, 20, 10, 10, 90, 10, 10, 10, 10, 10, 10, 10, 10,

10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10}; //second chip


 
  int test = 1;
  int channel = 0;

void setup()
{
  Serial.begin (9600);
  Tlc.init();
}

void loop()
{
  Tlc.clear();
 
  while (test == 1)
  {
    long currentMillis = millis();    // Get the current millis
   // Serial.print("------------->");
    //Serial.println (currentMillis);
   
    for (channel = 0; channel < numOfChannels; channel++)
      {
        float numberOne = (currentMillis * duePiMillis);
        float numberTwo = numberOne / cycleDuration[channel];
        int myValue = (maxValue/2)+(maxValue/2)*(sin(numberTwo));
        Tlc.set(channel, myValue);
        Serial.print (channel);
        //Tlc.update(); //per fare la ola
      //  Serial.print(":");
        //Serial.print (myValue);
        //Serial.print("\t");
       
      }

  Tlc.update();
  //Serial.println ();
  }
}

Comments and advices are very welcome!!

Almost finished the coding.. i'll post that soon so you can check and tell me what you think. It seems to work!!
But I got another question about the chip: I tried to add another one, to see what it would like with 32 leds... but I can't find the file that should be deleted after making changes in the library (following the reference):

"All the options for the library are located in tlc_config.h, including NUM_TLCS, what pins to use, and the PWM period. After changing tlc_config.h, be sure to delete the Tlc5940.o file in the library folder to save the changes."

Tlc5940.o  Where is it????

thanks

Could you post the working code, I am interested in the same thing

Thanks