Low Cost, Audio Speed Digital Oscilloscope

The goal of the project was to design a low-cost digital oscilloscope targeted at students, hobbyists, and researchers. The requirements of the oscilloscope were three-fold: 1) cost less than $100, 2) capture frequencies over the range 20Hz–20kHz, and 3) constructable with a basic soldering iron and limited soldering skills. The primary parts of the oscilloscope are two Atmel ATmega644 microcontrollers, an Analog Device AD7825 ADC, and an NTSC television. One of the microcontrollers is used to generate an NTSC television signal, and the other is responsible for acquiring and processing samples from the ADC. The oscilloscope implements many of the same operations as a commercial oscilloscope. The user can start/stop the display, arm a single sequence, adjust the time division, adjust the voltage division, and adjust the trigger value. When the display is stopped, the user can also control a cursor which has time and voltage readouts. The supported time divisions are 0.5ms–5s, and the supported voltage divisions are 156mV–5V. All the specified requirements were met satisfactorily. The total cost of parts required for the oscilloscope was only $65.51, well within the specified budget. The oscilloscope can display signals up to 40kHz with at least 10 samples per cycle, which is better than the requirement of 20Hz–20kHz. Finally, the oscilloscope was designed entirely with parts that could be soldered by hand. Report Approved by Project Advisor: Date: