[chbot] Anyone making PCBs?

[Andrew Errington]

Ok, it's assembled and partially tested, and it works!

Soldering SMD is (are?) tedious.  But, it's done.

First I filed the edges of the PCB down, including the copper trace that 
marked the board edge.  Then I covered the whole board with solder.  Next, I 
used desoldering braid to remove most of it.  The gaps between traces and the 
ground islands were wide enough to stay clear.  Then I soldered my components 
one by one.  The trickiest one was an LDO regulator in a SOT-23-5 package.

The LED is supposed to light when the voltage drops below 10.36V.  This is 
the 'empty' level of my 10 pack of NiMH cells.  If I see the LED light up 
when the pack is being used I know it's time to recharge.  I haven't tested 
the threshold voltage exactly, but the LED is off when I connect it to the 
pack (should be about 12V or more) and on when I connect it to a 9V battery.  
If I tap the 7th cell in the pack the LED lights.  So, it's in the ball park.  
I have space on the PCB to add another resistor to adjust the voltage 
divider, but I'll get hold of a bench PSU and multimeter to test it properly.

So, it's possible to do this all with little in the way of exotic chemicals or 
equipment.  I used the following:

KiCAD software
Laser printer
Supermarket advertisement paper
Abrasive cleaning pad
Acetone (nail varnish remover)
An iron
Soapy water
Hydrochloric Acid (maybe can found as Muriatic Acid for cleaning swimming 
pools)
Hydrogen Peroxide (can be found for cleaning contact lenses)
Plastic pot with lid
Rubber gloves
Single-sided copper-clad PCB material

I used about 20ml of acid and 20ml of peroxide.  My board is about 12mm by 
30mm.  It took about 20 minutes at room temperature.  I believe the etchant 
can be reused for quite a while.

That's all for now!

Andrew