Saturday, May 3, 2014
ECG: Circuit
- Infrared emitter and detector
- 1 x 15ohm, 1 x 10kohm, 2x 100ohm, 1x 1kihm resistors
- 1 x 1uF, 2x 100uF, 1x 10uF capacitor
- 1 x 741 Op-Amp
IR Emitter
The group used a 15ohm resistor, to obtain a bright IR source without burning the emitter.
IR detector
The group use a IR detector to detector the IR reflect from the user body, with some tests the group found that fingers will give the best signal.
The group used a 10 kohm resistor, to prevent burning the IR detector
The group has tried not using any resistor and 15 ohm resistor, which end up burning the IR detector.
OPAPM
The signal received from the IR detector is too low for observe and calculation, so an amplify is needed for a readable signal.
The group used LM741 signal amplify from the ECE lab
Filtering
The signal received after amplify has a lot of noise that makes the data inaccurate, so a RC filter is designed to reduce the noise after amplify.
