Purpose: My "snowflake" display for Christmas consists of 3 x 7 foot high displays
of 96 seven-watt lights each. The "simulator" is about 1 foot square and consists of
96 LEDs...smaller and fits on my desk. I made 3 of these LED boards for
programming and testing.
This is the PCB layout. Note almost a full letter-size page. The 20 pin IDC connector
at the very bottom center interfaces with the existing snowflake controller that I use to
drive the 3 triac boards for the big display.
One board under test using the MikroElectronic V7 Development board
Snowflake Simulator adaptor board at bottom.
The adaptor board plugs into the space that
originally had a 16CP05 LED driver chip. U2 and U3
are ULN2803 Darlington drivers.
These are the three boards which represent the larger 7 foot diameter displays
that I put outside. Each has an adaptor board that connects to the Snowflake
controller (not shown but it is in that mess of stuff at bottom of photo).
Partial schematic of the Snowflake simulator boards illustrating the matrix
method of driving the 96 LEDs. The 16CP05 driver shown here was replaced
by the adapter shown below.
Schematic of the adapter board, concept shown at bottom left, actual
schematic at upper right. I kept the 16CP05 pinout for reference.