ultraviolet led box -for making pcb's @ home

[john-nafp]

ultraviolet exposure device i built few months ago. it is controled by an arduino pro mini and has a 7 segment display to show the set and remaining exposure time. it uses ultraviolet leds(49 total)bought cheap from ebay.

you can wire the arduino and the rest components using the diagram below.this way i made it too.you can connect any common cathode 7 segment display as long as you know witch pin is the segment shown in the diagram.or you can find it by applying about 3volts to each pin to see witch segment lits and write it down.(as i did)or downloading its diagram if exists..

then programm the arduino with the code given in the link below.you can skip the circuit with the mosfet and the optocoupler and connect a 5 volt relay as shown in the diagram(relay output & ground) to controll the leds.


and here is a video i made on my youtube channel about this project

Arduino code

 

[betwixt]

Note that most commonly available UV LEDs have a much longer dominant output wavelength than the 'sky blue' fluorescent tubes used in commercial exposure boxes so the time needed for exposure may be longer than anticipated.

Brian.

 

[john-nafp]

you might be right, but the average waiting time that worked good for my pcb exposure was about 1-2 minutes,so i dont mind waiting this time.at least i dont need to be faster than this..also the time depends on how many transparent sheets you place on the pcb(to achieve darker black),again this depends on how good the printer prints solid black on the transparent sheet.here in greece i cant find transparent sheets for inkjet printer at reasonable price so im printing on semi-transparent paper that increases the exposure time also..but again that's is not a problem..
one thing i dont know is how harmful that kind of light is for humans..i really dont know..

john.

 

[Relayer]

Hello john-nafp,
I think you've done a fantastic job on this project. :clap:
Your use of using an old printer case is ideal and
the entire thing looks like it just came out of a
factory assembly line...
Once again, WELL DONE!!! 10/10 :thumbsup:
Regards,
Relayer

 

[john-nafp]

thanks for your good comments..indeed that printer cover looks like it was designed for that project..thanks again.:thumbsup: