UV LED Matrix - ghollyp/uvled GitHub Wiki

The inspiration to use UV LED matrix to make caynotype patterns came from the cheap 8x8 LED matrix modules driven by MAX7219. One MAX7219 chip can drive 64 individual LEDs and multiple chips can be daisy-chained together to create bigger matrix. 4-wire SPI interface connects the chip to the microprocessor (Raspberry Pi in my case). Wiring the matrix is quite simple.

MAX7219 LED Matrix Schematics

Unfortunately none of the available LED matrices was ultraviolet, so I soldered some test matrices on universal PCBs to proof the concept that the UV LEDs will expose the cyanotype paper. When using inexpensive LEDs from ebay you must expect that the quality vary. It is important to pick diodes with similar intensity if possible.

Test Matrix

After testing several types of 5mm and 3mm UV LEDs from ebay/aliexpress I have asked my friend to design first revision of 16x16 LEDs matrix for me.

16x16 matrix

16x16 matrix

The PCB is made for 256 3mm LEDs (16 x 16, 80.0 x 80.0 mm) with pitch 5mm and consists of 4 chained MAX7219 chips each driving 64 diodes. I have tested following diodes so far:

  • 3mm Round UV LED with wavelength 390-395nm and beam angle 20 degrees from ebay
  • 3mm Flat top UV LED with beam angle 120 degrees from ebay In order to solder the diodes evenly, I have made 3d-printable stenctil.

8x8 matrix

8x8 matrix

PCB is made for 64 5mm LEDs (8 x 8, 60.96 x 60.96 mm) with 7.62mm (300mil) pitch. Tested diodes:

  • 5mm Round UV LED with wavelength 390-395nm from ebay
  • 5mm Straw hat UV LED with beam angle 120 degrees from ebay

Printable solder stencil.

1x64 line 3mm pitch

1x64 line

PCB is made for 64 LEDS with rectangular 2x4mm base and 3mm pitch in one line. Tested diodes:

  • 2mm Round top, 2x3.9mm base UV LED with 400nm wavelength and 30 degree beam angle from ebay
  • 2x3x4mm Rectangular UV LED with 390-400nm wavelength and 30 degree beam angle from ebay.

Solder stencil for 2x3x4mm Rectangular LEDs

1x64 line 2.54mm pitch

1x64 line

PCB is made for 64 LEDS with rectangular 2x4mm base and 2.54mm (100mil) pitch in one line. Tested diodes are same as above. Solder stencil for 2x3x4mm Rectangular LEDs

1x64 line 2.54mm pitch SMD 0805

1x64 line

PCB is made for 64 0805 SMD LEDs with 2.54mm (100mil) pitch in one line. Diodes tested:

  • 0805 UV LED 390-410nm wavelength from aliexpress

Solder stencil for 0805 LEDs