Embedded Etcher

Design files related to a photo-sensitive layering method etching machine everyone can build to produce prototypes quickly at home or in the lab.

Architecture

The etching machine consists basically out of two parts. The first part is a UV light, which is used to develop a photo-sensitive PCB. Once this has been done. The PCB has to be treated with sodium hydroxide (NaOH) dissolved in water. This removes the UV-sensitive plastic, where it has been tackeled by the light.

The second part is the actual etching machine, which is designed to be compatible to euro cards (and even bigger ones). The etching machine is either filled with sodium persulfate (Na₂S₂O₈) or iron(III) chloride (FeCl₃) dissolved in water of course.

RedheadOS

One of the byproducts of this project is a small real-time OS, which is ment to run on embedded platforms. It is based on fixed priority scheduling and includes some nice accessories, so one does not always have to reinvent the wheel for every new project.

UV Light

Driver Extension Board

This PCB is made to fit the Nucleo-F103RB development board from STM. Features:

• 64 LED driver stages.
• 6.4 A (0.1 A per stage) and 24 V max. input.
• 0.2 A max. and 350 mW dissipation max. per stage. Stages can be left floating if unused without the threat of damaging the device.
• 10 Bit Digital-to-Analog Converter (DAC) to steer the driver combined with feedback amplification to achieve a tremendously fine resolution.
• Optional potentiometer to set the current.
• Control loop to guarantee the desired current and respond quickly to changing the setpoint.
• 2 rotary encoders and 1 tactile switch.
• I2C header.
• SPI header.

It is important to mention, that the resistors for the non-inverting amplifier in the feedback loop are optimized to result in a maximum current of 33 mA for 3.3 V in order to achieve higher currents different resistor values have to be chosen.

Cuvette

The cuvette can be handcrafted. It is possible to buy the five glass pieces need at a glassers shop or to cut it oneself. The glass parts can be glued together with silicon.