Active electrodes

First prototype of active electrodes

Comparison of active/passive electrodes

	Active electrodes (unshielded cables)	Passive electrodes (shielded cables)

Calibration signal with 1M resistor
Calibration signal with 1M resistor - lower range
Calibration signal with no resistors
Calibration signal with 10M resistor
Calibration signal with 10M resistor, wide spectrum
Calibration signal with 200k resistor, wide spectrum

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	Active electrodes (unshielded cables)	Recorded signal saved as sound file mono 256Hz (micorsoft wav format)

Calibration signal with no resistors		active_noR.wav
Calibration signal with 1M resistor		active_1M.wav
Calibration signal with 10M resistor		active_10M.wav
Calibration signal with two 1M resistors		active_two1M.wav
Calibration signal with two 10M resistors		active_two10M.wav

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Here are real eeg signals from my forehead.

Passive (original wav)

Active (original wav)

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Active and passive electrodes connected both to the same calibration signal

Only active electrodes connected to calibration signal but with 440 ohm resistor between electrodes

Active and passive electrodes connected both to calibration signal but with 440 ohm resistor between electrodes

Again the same circuit but different result: active and passive electrodes connected both to calibration signal but with 440 ohm resistor between electrodes. The calibration signal wires are soldered to active electrodes. Passive electrodes are put on active (without soldering).