This page is about a simple ECG based on an ATMEL ATMega32 running at 3.6864Mhz for AD conversion, simple signal processing and data storage handling on an MMC/SD Memory card and/or transmission over RS232.
The input amplifiers are basically taken from Lars Stollenwerk's site , who used a 4th order bessel low-pass for getting rid of the 50Hz power supply induced frequency you'll find everywhere. On the other side I observed in a hospital that the ECGs there havn't had much of a low-pass, since there was a lot of 50Hz oscillations as long as the related electrodes weren't connected yet. Therefore I'll plan to test how the quality of the electrodes might effect the 50Hz part of the measured signal.
This design can be run battery powered, although the current power consumption of 250mW is quite high. Especially the memory card needs some power, and the voltage resulators for supplying -4,5V; 0V; 4,5V; 5V; 3.3V surely take their part there too.
The batteries cannot be simply replaced by a usual power supply, since they usually do not provide a stable voltage.
Current setup (only one channel at the moment): click
Current setup (three channel version): click
Example measurement: click