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[on:]

Hi all!

Ok, I'm missing a bit a page where you can discuss ongoing projects so I'm doing a little experiment with this little build-along where I will post my ongoing progress on this lamp. Feel free to comment/suggest at any point. (Although I'm afraid I figured out most of it by the time now.)

There you go:

This lamp schould feature a total of 13 RGB-LEDs and 13 White LEDs to provide mood light as well as the possibility for white light for example to read. This lamp also features 9 capacitive buttons to control the various functions. The whole construction is being mounted on the backside of an A4 sized picture screen.


Starting:
The first thing I did was find out whether I was able to get the touch-buttons to work. The IC I used is the Atmel QT100A which provides one touch button.
After a lot of research and digging through various touch button guides, I started creating a mini prototype board for the chip. The problem I encountered was however that there seemed to be no concrete example on resistor and capacitor sizes for the schematics. So I took a wild guess and ordered the parts.
which... luckily worked out quite well :-)

Schematics:


Data:

Cs = 22 nF
Cx = 12 pF
Cb = 100nF
Rs = 4.99 kOhm

Although, the touch buttons are quite sensitive, even through the glass plate it should work fine.
If anyone wants to make something similar, decreasing the capacity of Cs should work to decrease sensitivity.

Here you go test design:



And Mass production:


And conclusively testing:



So much for this first episode, stay tuned in for further progress!

[Reply #1 on:]

PART II:
Next up is the setup of the LED's

So resistors all calculated, so much for the prototype:






And again, mass soldering... darn they're small....

No problems here, see you soon with episode III :-)

[Reply #2 on:]

~ intermission ~

[Reply #3 on:]

Part III
(Dedicated to Grumpy_Mike)

The 6 TLC's are soldered now. The first three will power the RGB-channels, each running at 40mA with 13 LED's each. the later three provide power for the white LED's running at 100mA.

Some Data:

Resistor on Pin 20
TLC 1 to 3: R = 1000 Ohm
TLC 4 to 6: R = 400 Ohm


Maximum Power dissipation: 2.456W

Assignment of LED's:

Code:

TLC1: RRRRRGGGGBBBB - 2.044W
TLC2: RRRRGGGGGBBBB - 2.088W
TLC3: RRRRGGGGBBBBB - 2.088W
TLC4: WWWWW         - 2.350W
TLC5: WWWW          - 2.000W
TLC6: WWWW          - 2.000W

Cheers!

[Reply #4 on:]

Part IV

Now all the RGBs and White LED's have been soldered and just need to be glued down.
The capacitive touch fields are made of soldering-blobs, due to the lack of any decent circular solderable thin-enaugh material available.
For now I've tested them, they need a maximum of 2 minutes to adapt to the environement, but after that they work perfectly fine. At least without interference from LED currents running around. That will be tested soon.

Cuts in the frame to make room for wiring and LED's


Touch protochips glued....


The infamous Lead-blob-button


Some pictures along the way





Two more things to go: Status LED' for the touch buttons and programming.

So, last episode this year, see you next!

Happy New Year to All!

 [smiley=beer.gif]

[Reply #5 on:]

Great build! I have been tempted to go all out on a mood lamp using 3W RGB LED's. I ordered 20 of them the other day just in case I get the urge

Are those the TLC5490's? Are you paralleling the outputs? I was thinking of doing the same thing but wasnt sure if it'd work?

[Reply #6 on:]

thanks :-)

Yes those are 6 TLC5940, not sure what you mean with paralleling the outputs, but in my case there is one output for one LED.
If you want to use 3W LEDs I recommend using the TLCs only as a pwm controller for a transistor to switch the LEDs, since the maximum power dissipation is approximately 2.456W per DIP IC... so you could only drive one LED per TLC, and not even at maximum...
You could use the Arduino and a library that adds PWM to all pins to drive transistors for the LEDs.

[Reply #7 on:]

Part V

As far as there aren't any other Ideas coming along I've finished the physical build by now.
I've added a vibration motor to add physical feedback when operating the touch-buttons, and a reset button for easier access to it.

[Reply #8 on:]

Hmm, I've encounterd a most disturbing error.

When I want to pass on multiple Values to the TLCs they begin to flicker. I can pass 32 values which works fine, but when I pass 48 (3tlcs) they begin to flicker.

I've read somewhere that this may be a problem with the amount of data to pass on?

However, ruled out are:
lack of power. (all leds can be on)

I've also tried to add multiple tlc.update before each new transmit, as well as adding a delay which didn't work.

Cheers!

[Reply #9 on:]

Part Vb

Since last time I've added an additional reset button to reset the lamp hanging on a wall, and a capacitor to smooth out eventual voltage fluctuations.

Anyway I haven't overcome the flicker-error, although its getting better for no reason.. I can pass all values within the loop except the last one...



Now with 100% more video! (running the knight-rider example)
http://img684.imageshack.us/i/83161252.mp4/