Its a simple function generator. While the function generator module (AD9833) could generate sine-, saw- and rectangle- waveforms, the button of the rotary encoder gave me a headache, i decided not to change the waveform and go with a sine wave only as output.

The adjustment of the frequency can be changed by rotation of the rotary encoder. When you turn it slow the lower decimals get change, as faster you get the higher decimals are changing.

slowest rotation - 10^0 Hz
slow rotation - 10^1 Hz
normal rotation - 10^2 Hz
fast rotation - 10^3 Hz
fastest rotation - 10^4 Hz

Parts:
-Arduino nano based
-with AD9833 Func.Gen.-module,
-a 128x64 oled display,
- 7805 Voltage regulator
-BNC and DC-Jack.
-rotary encoder

Case: www.thingiverse.com/thing:3151542