The PCB from the top of the picture is the power panel. It contains the LM317 current regulator, fuse, switching transistors, etc.
The lower PCB is the timer and control unit
The chassis is made from L shape aluminum and it holds the whole assembly and the two 3mm thick glass sheets.
Initially I planned to make an enclosure also, but it works this way also, and any DIY enthusiast know that making an enclosure is the most difficult part.
As you can see, the power panel was hand drawn and etched that way, pretty messy work, I'm not proud of it :-D
The timer board was the first piece of electronics made by lithographic method (exposed using an egg timer), you can see the difference.
I made this from a 6mm brass pipe, on one end a 5pin radial connector glued with epoxy and on the other end the PCB with the UV leds and with the heatsink glued to it.
Still a messy hand drawn PCB. It could be made by heat transfer but it was quicker to just draw it using a permanent marker.
In the middle is the soul of the device - the two 5W 400nm UV leds as close as possible to each other to have the best spot light to prevent shadow ghosting.
At the top you can see two little red leds - those are for the ambient lighting used for setting up the film and stuff. Useful if you expose something which is more sensitive to light than Positiv 20.
Really awesome build! I'm thinking of basing my own exposure station off of yours.
ReplyDeleteDo you have a schematic of the LED head? I can kind of tell what's what, but I can't quite tell how the grounds tie up and what that red wire going left to right is for. Did you ground the right arm of the support pipe?
Is orange wire the temp sensor? It only has one wire?
Unfortunately the head is hand drawn directly on the PCB, so I didn't make any schematic or PCB drawing. I will update the documentation as soon I will have some time.
ReplyDeleteThe idea is to have the UV leds in series from +12V to J2 pin 2. The tick red wire is +12V (J2-1), and the tick brown wire is linked to J2-2 (SCH_UV_power.pdf). I made a new head with 4 LEDs with just changing the power source to a 18.5V one.
The black wire is the negative pole of the fan linked to J2-4, the positive of the fan is tapped to the +12V with that left red wire.
Those small horizontal red wires are for the two little red LEDs, one is tapped to +12, the other is linked to J2-3 through the pipe.
The orange wire is linked to J2-5 - is meant for temperature sensing but I haven't implemented it.
The mast pipe isn't grounded.
Cheers.
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ReplyDeleteSuper build! but, what a Fuses sets for Atmega8?
ReplyDeleteHi,
DeleteI set up only the BODLEVEL and SUT_CKSEL fuses: BODLEVEL=4V3, SUT_CKSEL=EXTFSXTAL_16KCK_14CK_65MS
The rest remained the same.
Basically you need external clock with high speed crystal, and max. start-up time (for safety), and some sort of low voltage protection to prevent EEPROM corruption.
Make sure that the CKDIV8 is cleared and the SPIEN remains set.
Cheers,
Arpad
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