Author Topic: PCB UV exposure box  (Read 1505 times)

Offline AdeV

  • Madmodder Committee
  • Hero Member
  • *****
  • Posts: 2148
  • Country: gb
Re: PCB UV exposure box
« Reply #25 on: January 17, 2019, 06:06:42 PM »
It's my doorbell!

https://madmodder.net/index.php/topic,12284.msg146395.html#msg146395

I couldn't make the stripboard version small enough, whilst having the sideways pointing LEDs. Even now I've had to go for the 3mm versions... not yet sure my blue ones are bright enough, I may need a smaller resistor. I don't mind overdriving the blue one a bit, as it's only on as the bell is actually ringing.

I'm also not sure what effect having the computer bits outside the door (in the switch box) will do. They may fail due to environmental issues; but equally, I wasn't sure if the capacitive sensor would work at the end of a long run of cable. Worst case scenario, I'll compromise and have the switch/LEDs outside, a small box inside with the chip, and the long wire running back to the bell box.

I'll post a writeup on the doorbell once I've got the box sorted, unless I get a flood of PMs' saying "for god's sake nooo!"  :scratch:
Cheers!
Ade.
--
Location: Wallasey, Merseyside. A long way from anywhere.
Or: Zhengzhou, China. An even longer way from anywhere...
Skype: adev73

Offline philf

  • Hero Member
  • *****
  • Posts: 876
  • Country: gb
Re: PCB UV exposure box
« Reply #26 on: January 18, 2019, 09:00:46 AM »
It's my doorbell!

I think I'm excused for forgetting - it was September 2017 you started on this project!
Phil Fern
Location: Marple, Cheshire

Offline AdeV

  • Madmodder Committee
  • Hero Member
  • *****
  • Posts: 2148
  • Country: gb
Re: PCB UV exposure box
« Reply #27 on: January 18, 2019, 01:51:57 PM »
It's my doorbell!

I think I'm excused for forgetting - it was September 2017 you started on this project!

Totally excused... I thought the forum must have it's years wrong at first... 15 months since I figured it'd "only take a weekend". Oops!

I wonder how many visitors I've missed....?  :scratch:  :lol:
Cheers!
Ade.
--
Location: Wallasey, Merseyside. A long way from anywhere.
Or: Zhengzhou, China. An even longer way from anywhere...
Skype: adev73

Offline awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 6745
  • Country: gb
  • East Sussex, UK
Re: PCB UV exposure box
« Reply #28 on: January 18, 2019, 05:27:05 PM »
Well I stood there pushing the bell for hours hoping for a brew, but gave up and found a cafe  :doh:
Andrew Mawson
East Sussex

Offline AdeV

  • Madmodder Committee
  • Hero Member
  • *****
  • Posts: 2148
  • Country: gb
Re: PCB UV exposure box
« Reply #29 on: January 19, 2019, 04:55:42 AM »
Well I stood there pushing the bell for hours hoping for a brew, but gave up and found a cafe  :doh:

I was probably out  :lol: making really slow progress on a doorbell...  :poke:
Cheers!
Ade.
--
Location: Wallasey, Merseyside. A long way from anywhere.
Or: Zhengzhou, China. An even longer way from anywhere...
Skype: adev73

Offline raynerd

  • Madmodder Committee
  • Hero Member
  • *****
  • Posts: 2885
  • Country: gb
    • Raynerds Projects - Raynerd.co.uk
Re: PCB UV exposure box
« Reply #30 on: February 03, 2019, 07:11:33 AM »
Nice project Ave. I built a similar box years ago. However, I did get a bit disheartened with it as despite making chemicals to the same concentrations, I kept getting mixed results and could never seem to nail a reliable method from start to finish... too trial and error in most cases! Well done on your build.
Chris

Offline AdeV

  • Madmodder Committee
  • Hero Member
  • *****
  • Posts: 2148
  • Country: gb
Re: PCB UV exposure box
« Reply #31 on: February 03, 2019, 08:09:58 AM »
Thanks Chris!

I also had a few failures - it took 2 complete (apart from some small offcuts) of 160x100mm single-sided presensitised board, just to get one 22x30mm (ish) board completely successful! Most of that was trying to get the exposure right, though, so I expect future boards to go better. The other thing, I used sodium metasilicate (aka waterglass) as the developer, after reading an old web page (http://www.electricstuff.co.uk/pcbs.html) which suggested that using plain sodium hydroxide was a pain in the arse; and, apart from when I'd overexposed the board, it did work a treat. So well, in fact, I made an entire bottle full of concentrate.... unfortunately, something's gone a bit wrong with it - see picture; it should be crystal clear, the white is a solid block of.... dunno what. I'm not sure if it's recoverable or not. Still... the raw chemicals are cheap, I can just make some more when I need to.

One of the next jobs I want to do is get the timer circuitry onto a PCB, so I can free up the breadboard for the next* project.

* Any suggestions from the floor?

Cheers!
Ade.
--
Location: Wallasey, Merseyside. A long way from anywhere.
Or: Zhengzhou, China. An even longer way from anywhere...
Skype: adev73