Editing Pulse Necklace 15Nov2009
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==Op-Amp Experiment== | ==Op-Amp Experiment== | ||
Chung-Hay bought a couple AD 620 op-amp chips to experiment with bypassing the Open ECG chip at filtering/amplifying the bio-electric signal. We worked off of the lab document [ | Chung-Hay bought a couple AD 620 op-amp chips to experiment with bypassing the Open ECG chip at filtering/amplifying the bio-electric signal. We worked off of the lab document [www-univie-ac-at_cga_courses_BE513_Instrumentation_pe3quc01.pdf BE 513 Lab], in addition to the AD 620 data sheet. The sample circuit for detecting ECG in the AD 620 data sheet included two other op-amp components. We have yet to figure out what the op-amp circuit attached to the gain-control resistor does... Chung-Hay is going to seek EE assistance on that front. | ||
To look at the output signal from AD 620, we resorted to a virtual oscilloscope - link and code are in the next section. Unfortunately, we saw only noise from the oscilloscope. We tried switching the gain-control resistor from 98 ohms (two 47 ohm resistors) to 1 kohm. That only lowered the amplitude. We were using red dot electrodes, so the ECG signal was entering the chip reliably. More work to be done on this front. | To look at the output signal from AD 620, we resorted to a virtual oscilloscope - link and code are in the next section. Unfortunately, we saw only noise from the oscilloscope. We tried switching the gain-control resistor from 98 ohms (two 47 ohm resistors) to 1 kohm. That only lowered the amplitude. We were using red dot electrodes, so the ECG signal was entering the chip reliably. More work to be done on this front. | ||
==Oscilloscope Code== | ==Oscilloscope Code== |