Custom PCB. Shown with the four jumpers removed that connect the custom PCB to the USB power, CP2102, TTL inputs, and serial LCD, and stimulator output.
1 Hz-50 kHz noise spectra. Measurements were taken across a 1 kΩ load resistor with the stimulator set at constant currents of 1.0 mA, 5.0 mA, and 10.0 mA using a Hewlett Packard 3562A signal analyzer. The SNRs over the full bandwidth are 60 dB, 72 dB, and 75 dB, respectively.
Stimulator output. Voltage measured across a 1 kΩ resistor with a Tektronix TDS 2012B oscilloscope. (A) (Upper trace) S1-Sine mode example. Three 3.0 mA S1 pulses of 10.0 ms duration and period 50.0 ms, followed by a 25.0 ms delay, followed by a 300.0 ms duration 50 Hz sine stimulus of amplitude 8.0 mA with a −4.0 mA offset and 270° starting phase. (B) (Lower trace) Streaming mode example. A damped sine wave specified by 5000 currents loaded from a text file in the GUI. Values are updated every 175 μs. This trace was recorded at 100 ms per division and overlaid to make efficient use of the figure.
Induction of Arrhythmia in a Rabbit Heart using S1-sine mode. Electrogram was recorded using two Ag-AgCl pellet electrodes (EP8, Word Precision Instruments) placed on opposite sides of the heart. Six 1.0 mA S1's of 2.0 ms duration and 300.0 ms period followed by a 300.0 ms delay precede a sine wave with 4 mA amplitude, 90 ms period, 0° offset, 0.0 mA offset, and 2.0 s total duration.
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