This is a quad output variable frequency oscillator. It is based on the Adafruit Si5351A Clock Generator Breakout Board. The fourth output is a simple PWM pin driven by the TimerOne library. The whole thing is controlled by an Adruino (ATmega328).

1. 8KHz to 160MHz
2. 8KHz to 160MHz
3. 8KHz to 160MHz
4. 0 to 10KHz

• Short press on the big button cycles through the outputs
• Long press on the big button enables/disables the current output
• Turning the knob will increase/decrease the value of the current output
• Short press of the knob will cycle through the positions of the current output
• Long press of the knob will zero out the current position of the current output
• Pressing the small button will save the current settings (in the eeprom)
• If nothing is pressed for 10 minutes, a screensaver will appear

• Jason Milldrum's Etherkit Si5351 library: https://github.com/etherkit/Si5351Arduino
• TimerOne library: http://playground.arduino.cc/Code/Timer1
• Oliver Kraus' u8g library: https://github.com/olikraus/u8glib
• Thomas O Fredericks' Bounce2 library: https://github.com/thomasfredericks/Bounce2

Assembled:

Breadboard:

Fritzing: