DIY ECG and Pulse Oximeter with LM324 OpAmp (1 of 2)

ECG using a single LM324 which doubles as a pulse oximeter. This device can be used with chest pads to yield an ECG or with an LED and phototransistor for pulse oximetery. IMPROVED ECG PROJECT: https://youtube.com/watch/sP_-f5nsOEo Project page: https://www.swharden.com/wp/2013-04-1... Description: Single LM324 quad operational amplifier using all 4 amps: (1) virtual ground, (2) preamplifier, (3) lowpass filter, (4) final amplifier and second lowpass filter. It doubles as a pulse oximeter (near rail-to-rail swing at 12V and 5V) with a phototransistor, and an ECG (about 0.5 V output).