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5x4 inch LED enlarger head.


So I have moved up to 5x4 and this means a LED head (anybody want a Dicromat for the DeVere?).

Head on 504
And there it is on my DeVere.
 
Because of the much larger power consumption of this head compared to the Led Enlarger all the Analyser does now is send data to the head giving grade, on/off and focus.  A micro in the head decodes this and sets two PWM outputs to vary the level of blue and green.

Leds and rear panel

At the back is the PWM to constant current converters, two for blue, three for green and one for the red leds.  Using a 24V power supply with these leds (lumileds 1W lambertian luxeon emitter) leads to 6 in series with a bit of spare voltage for control, the two red leds are for safe illumination for bordeless print positioning.  The funny pattern for the leds is what it takes to give an even illumination on the baseboard for 12 blue and 18 green leds.  The white stuff below the leds is a double sided heat sink sticky tape, it does stick very well, I broke a led trying to get one off.  Below the white stuff is a 10mm thick ali plate to conduct the heat to the heatsinks, I admit it's a bit ott but thats what I had.  The socket on the right of the front panel is for Microchip ICD, brilliant idea, lets you program, debug and lots more without pulling the chip.

B G O O O B O B O O O G B
G O O O G O G O G O O O G 
G B O O O O O O O O O B G
O O O O O O O O O O O O O
O O O O O O O O O O O R O
O R O O O O O O O O O O O
O O O O O O O O O O O O O
G B O O O O O O O O O B G
G O O O G O G O G O O O G
B G O O O B O B O O O G B

This is the layout for the leds on a 10mm grid for a diffuser 140 * 110mm 40mm from the led surface, I was quite supprised when I calculated this but it works.  If anybody wants to use this layout for a commercial product let me know.

Exposure times were another supprise, 3 seconds at f11 for a 10x8 grade 2, had to put a dimmer function in the software!

A PIC in the analyser 'looks' at the micro in the Analyser and decodes what is happening, sending it out as a seial data stream.  And another ICD socket.

Piggy back pic

Finaly, the control panel from the rear.

leds and control