Inspired by a project he found over on Instructables, Maker JoEtuuube has created an Arduino-based waveform generator using an 8-bit resistor ladder DAC that can precisely produce different common waveforms at frequencies between 1Hz and 20Khz in sine-wave, sawtooth, triangle and various ratios of square wave. It features a speaker and a small LCD display.

A neat thing about the LCD is that it’s actually a reverse-engineered display from a cheap pocket calculator. With his hack, JoEtuuube no longer punches each digit in directly; instead, he only taps the clear, +, = and 1 keys. He can then enter arbitrary numbers by typing in the right number of ones and adding them up. For example, 345 = 111 + 111 + 111 + 11 + 1.

The generator itself uses an Arduino Uno and runs off a 9V battery. In the video below, JoEtuuube provides a detailed walkthrough of the firmware and how everything works. You can also read more about it on Hackaday.

[Joekutz] wanted to re-build an audio-rate function generator project that he found over on Instructables. By itself, the project is very simple: it’s an 8-bit resistor-ladder DAC, a nice enclosure, and the rest is firmware.

[Joekutz] decided this wasn’t enough. He needed an LCD display, a speaker, and one-hertz precision. The LCD display alone is an insane hack. He reverse-engineers a calculator simply to use the display. But instead of mapping each key on the calculator and typing each number in directly, he only taps the four 1, +, =, and clear keys. He can then enter arbitrary numbers by typing in the right number of ones and adding them up. 345 = 111 + 111 + 111 + 11 + 1. In his video, embedded below, he describes this as a “rather stupid” idea. We think it’s hilarious.

The meat of the project is the Arduino-based waveform generator, though. In the second video below, [joekutz] walks through the firmware in detail. If you’d like a simple introduction to DDS, check it out (or read up our more in-depth version).

He also makes custom detents for his potentiometers so that he can enter precise numerical values. These consist of special knobs and spring-clips that work together to turn a normal pot into a rough 8-way (or whatever) switch. Very cool.

So even if you don’t need an R-2R DAC based waveform generator, go check this project out. There’s good ideas at every turn.