At first I created a 4 bit Data Logger in a small plastic box. The data was saved on a SD Card connected to a PIC18LF13K50 micro controller.
Because of the limitations of this unit, I created a better one with a PIC18F4550 controller. It can digitize 13 input bits, has a separate clock module and a color TFT display for settings and results.
Custom PCB 
Custom case
Data is stored on a SD Card with a time stamp. In the settings menu, certain parameters can be set like interval time, trigger, mode, number of channels used and total time.
The inputs can be configured for voltage ranges.
For testing, the signals can be viewed on the display before the real measurement take place.
After a measure period, the data can be read from SD card, with a in C# written program, for analyses.
