“In the lab, one often needs a repetitive signal of a certain frequency, shape and amplitude. It may be to test an amplifier, check out a circuit, a component or an actuator. Powerful waveform generators are available commercially, but it is relatively easily to make a useful one yourself with an Arduino Uno or Arduino Nano, see for example:
https://www.instructables.com/id/Arduino-Waveform-…
https://www.instructables.com/id/10-Resister-Ardui…
Here is the description of another one with the following features:
Accurate waveforms: 8-bit output using R2R DAC, 256-sample shape_
_ Fast: 381 kHz sampling rate
Precise: 1mHz steps frequency range. As accurate as the Arduino crystal.
Easy operation: waveform and frequency settable with single rotary encoder
Wide range of amplitudes: millivolts to 20V_
_ 20 pre-defined waveforms. Straightforward to add more.
* Easy to make: Arduino Uno or Nano plus standard components”