Page :

[ 1 ]

[ 2 ]

I Wanted to make a capacitive touch light switch (on/off) that would send singnals via WiFi to my automation system.  The assembly consisted of a PCB for the MPR121 chip,  an ESP8266 (on a NodeMCU dev board) and some LED's.  This would be attached to an acrylic face that allows light from the LED's to be diffused through it.

The schematic:

 

Top copper:

 

Bottom Copper (date should be 2016-03-12):

 

 

Here is the acrylic (translucent smoke color) with some cut vinyl stuck to it.  This was then painted and the vinyl removed to end up with an opaque piece of acrylic with a square area to allow the LED light to come through.

Here's the front of the board after etching and solder mask applied.  I liked 90 degree traces that day :)

Back of board after etching and solder mask applied (date should be 2016-03-12 !):

A closer image of the LED's.  These are common anode RGB right angle (side view) in a 1206 (actually 1204) package.

Another better look at a LED and with the diffuser in place.  The blue color is just some protective film on a square of clear acrylic.

Being a 1204 package these LED's were somewhat tricky to solder.  Originally I tried with some solder paste and some hot air.  This worked ok but when tested it by scrapin the solder just flaked away.  I ended up having to hand solder them under a microscope to see properly what I was doing!

Assembled and looking at it from the bottom.  The LED's are pretty bright as shown here shining THROUGH the PCB.

Also you can see here I mounted the NodeMCU board and MPR121 breakout in a manner which will allow them to be removed for use elsewhere in some other test projects.

Looking at it from the side with the PCB attached to the acrylic.

For a nice, shiny piece of acrylic this picture looks terrible!

The theory is apparent though;

1) the green light shining through the acrylic.

2) you touch the acrylic and it changes color (in the real world it also turns something on and off!)

 

	(Page 1 of 2)