Ferric chloride etching chemistry

etch

[ladyada] has republished an interesting snippet from the synthDIY mailing list. [David Dixon] discusses the actual chemistry behind ferric chloride based home circuit board etching. He concludes that ferric chloride is essentially a ‘one-shot’ oxidant. It can’t be regenerated and can be difficult to dispose of properly. The use of acidified copper chloride is a much better path and becomes more effective with each use, as long as you keep it aerated and top up the acidity from time to time. This etchant solution is actually the result of initially using hydrogen peroxide as an oxidant along with muriatic acid. You can see us using this solution in our etching how-to and while creating the board for our RGB lock. For more information on using hydrogen peroxide, check out [Adam Seychell]‘s guide and this Instructable.

Aside: [ladyada] has added the receiver code to the Wattcher project page.

Besmoke – fluid dynamics

Besmoke is a fluid dynamics engine. It is compatible with any multitouch system, as well as the accelerometer in an iPhone. It also accepts audio input. The audio input can turn it into a fancy music visualizer that would even work with live or acoustic music. Different frequencies cause fluid to be injected from different “emitters”. There’s great info on his page, including the papers that he based this off of. We’ve covered [Eric]‘s work before with his election party light system.

Autofocus assist light

afassist

[Aki]‘s Nikon D2H did not come with an autofocus assist light.  His other cameras have them, and he likes the feature, so he decided to hack one into his D2H. He wired into the AF system, so that his LED gets voltage when the shutter release is pressed half way. The circuit needs refinement though, he found that the light was staying on during shutter release and affecting his light metering. You can see the hack in action after the break.
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Parts: AT keyboard

atkeyboard

Last week we introduced a new version of the Bus Pirate universal serial interface tool. The last firmware update included an AT keyboard decoder library for both hardware versions.

There’s a ton of old AT keyboards making their way to the landfill. We’ll show you how to recycle one as an input device for your next project.

[Read more...]

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