Howdy!
I started this topic to give you instructions on how to build a UV Exposer for wiring printed with photoresist from an old scanner.
First, disassemble the old scanner, so that only the bare shell + the glass remain.
Put aside the front panel with buttons (if it doesn't have something like that, it's not a tragedy, make some buttons yourself), the inverter for the scanner lamp and the 12V power plug (if it has something like that).
Make the circuit according to the attached scheme, it is preferable to have 4 distinct boards:
the button panel recovered from the scanner
the panel with the LED display with 7 segments (the displays must be with common cathode)
main board
the inverter
If the scanner did not have the panel with buttons, you can make the display, the mainboard and the buttons on a single cable.
Program the PIC with the HEX.
The UV lamps are purchased on EBAY or on Aliexpress - I used 4 tubes that I inserted and connected to the inverter.
Mount everything and test it.
The 6 buttons are:
RESET - resets everything, turns off the lights and sets the timer to 0 seconds.
UP - increments the timer by 10 seconds up to a maximum of 9 min 59 sec.
DOWN - decrements the timer by 10 seconds
START - turn on the lamp and the timer will start, and when the time expires the lamp will turn off and "End" will appear on the screen. To confirm, press STOP or RESET.
STOP - turns off the lamp and the timer will stop, the remaining time being kept in memory. The message "End" will appear on the screen.
PREHEAT. Turn on the lamp for 1 minute to preheat it. At the end of the time, the message "End" will appear on the screen and the timer will return to the remaining time before starting the preheating.
Now...I didn't do the wiring because I don't have a reason, because I didn't have a PCB exposer to do the wiring yet :)- I did it until 9:59, because it is never necessary to expose the wiring for more than 10 minutes. Obviously, more can be done, up to 99:59, by adding a 7-segment display and giving up a button (note that the pins are all used) or changing the PIC with a bigger one. But I went for this PIC because it is cheap, it has an INTERNAL oscillator (no quartz is needed), so that anyone can install it without worrying about the quartz with its problems when pairing with the 33pF capacitors. - initially it was with increment/ decrement by 1 second, but I noticed that the button stuck out until you set it to 4:40 for example, so I changed it to increment/decrement by 10 seconds. I'm not talking about the fact that the differences from 1 to 10 seconds are small when exposed to UV light.
Obviously, I also tested the light intensity, comparing the brightness by connecting first a single lamp, then 4 lamps, and finally 6. The light intensity decreases a little, but in no case by half. Ochiometrically speaking, I don't have any kind of lux meter. I actually put 4 UV lamps and 2 normal ones, as a test, as in my project I put only the 4 UV lamps at the end. It is enough to uniformly cover the entire A4 sheet as long as the scanner has. And from 4 to 6, the difference in brightness is greater than that between 3 and 4 lamps (which is negligible). I measured the current consumed last year, if I'm not mistaken, it was 95mA. I will look tomorrow to see how many mA the whole installation "draws". And yes, ALL inverters run on 12V. The voltage is not critical, I must have between 9 and 18V, the circuit doing the job brilliantly thanks to the 7805 and the 100uF capacitor which is enough! All inverters are simple bistable with 2 NPNs and a traf with secondary baban (3-5000 turns), varistor and that's it. (fixed thanks to the varistor, I have an almost constant light intensity, no matter if there are 1, 2 or 4 neons!). I have a 12V/500mA SMPS source and it hasn't worked until now, so any 12V power supply takes the whole installation.
Thanks for reading.
I am simply exhausted and I shall be testing it on some skin patches for my psoriasis and on some of my ill plants soon.
With respect,
Zpek
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