Filear.com posted a cool hack that can be done in an afternoon if you have the parts handy. The author built a DIY oscilloscope using an Arduino Pro Mini and the LCD from a Nokia 3310. The Arduino is wired up to sample from an ADC port and writes those values to the screen to create a waveform. Two potentiometers control the sampling speed and input voltage for approximate time and amplitude scaling just like the real thing.
The prototype can only read positive voltage at 3V or less, but we feel like some simple circuitry could make this puppy quite powerful. Adding an adjustable regulator to take wider input voltages and transforming negative voltage to fall within the ADC’s range would be low-cost improvements. You could also have the Arduino print the current timescale and amplitude to the display for finer-grained control. The biggest limitation is perhaps the Arduino’s 8-bit ADC, which gives mediocre resolution for large signals. Maybe someone could do a version using a TI MSP430 with its range of 10-16 bit ADCs.
This is a great start for anyone looking to read or log electrical signals and display them. And at $40 even if you’re starting from scratch, it beats the heck out of paying $500 or more for a decent o-scope. As the author says, there are plenty of DIY scope projects out there, but few have detailed build instructions or open source code.
Have you built your own oscilloscope project, or used your ADC for something equally cool? Share it with the world in the comments.