Homebrew PCBs

Quoth Howard at 2008-06-07 23:51...
> Hi all
> I need a timer for my uv light box that i have just made this week
> range from about 0 to 10 mins would do the trick.
> 
> Anyone got any diagrams and pcb layouts (single side) for making one ?
> 
> something like, counts down then switchs off and sounds a buzzer ??

Mine does more than that - when it finishes, the display says "Enjoy 
Your Meal!".

It is, as you may have guessed, the control panel from a microwave oven. 
I always found dead (supposedly - I managed to resurrect a good few) 
microwaves easy to scrounge from the local repair shop.  Most people 
would rather buy a new unit than pay $200 to replace a $5 light bulb...

There are a couple of microswitches (door interlocks) that plug into the 
main board that need to be accounted for - the pins may need to be 
shorted out as these are safety devices to stop the thing from 
operating.  Once that's figured out, the magnetron relay is used to 
control the tubes (or whatever you are using).

Were I designing something from scratch, I'd probably use three BCD 
switches to set the time (measure in seconds - easier than 
minutes/seconds) and 7-segment LED displays or Nixie tubes.  You may 
wish to read this specification that I started writing for a kitchen 
timer for ideas:
<http://www.smiffysplace.com/nixie-kitchen-timer>

Cheers

M

-- 
Matthew Smith
Smiffytech - Technology Consulting & Web Application Development
Business: http://www.smiffytech.com/
Personal: http://www.smiffysplace.com/
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