[sdiy] Photosensitive PCB's

[Fortner Florian]

-----Original Message-----
From: Fortner Florian
To: 'Michael Schulze '
Sent: 24.05.02 19:23
Subject: RE: [sdiy] Photosensitive PCB's

Only used ready-coated PCB's (positive) myself, but I've never had
problems although I use a simple'n'cheap halogen headlight (with 500W)
as light source.
The only disadvantage is the rather long lighting-time: ~20 minutes (at
20cm distance, great for LARGE PCB's) but it works great and is
reproduceable every time. Give it a try!

regards,

flo

-----Original Message-----
From: Michael Schulze
To: synth-diy at dropmix.xs4all.nl
Sent: 24.05.02 18:08
Subject: [sdiy] Photosensitive PCB's

I'ma having a hard time getting the photo sensitive pcb process to work.
I've sprayed my own boards and exposed them with negative art.  When I
etch
there seems to be not enough contrast between light and dark, so the
traces
are not clearly defined.  By the time I can see the fiberglass in
between
the traces the traces are half gone too.

Maybe I am spraying too much coating on???

I've ordered the positive boards to see if that is easier.

Any suggestions on suitable light sources for positive vs. negative
boards?
Seems sunlight is too unpredictable - 4 minutes of noon sun in Ohio is
not
the same as 4 minutes of noon sun in Florida!

> From: René Schmitz <uzs159 at uni-bonn.de>
> Date: Fri, 24 May 2002 17:15:57 +0200
> To: "Sandro Traversi" <straversi at libero.it>, "Michael Schulze"
> <michael.schulze at oberlin.edu>, <synth-diy at dropmix.xs4all.nl>
> Subject: Re: [sdiy] thermistors
> 
> At 16:06 24.05.02 +0200, René Schmitz wrote:
>> low resistance when some threshold voltage is reached. Ususally they
> 
> Nonsense, instead:
> *high* resistance when some threshold *temperature* is reached.
> 
> Cheers,
> René
> 
> 
> 
> 
> 
> -- 
> uzs159 at uni-bonn.de
> http://www.uni-bonn.de/~uzs159
> 
> 
>