Bio-Rad Gene Pulser Xcell™ Electroporation Systems - Manual (Page 49)

• From the User Preferences screen press 3 or use the Up or Down Arrow keys to highlight “Sleep
function”, then press Enter to select and to view the Sleep Function screen (Figure 3.37).
Sleep Function Screen
Fig. 3.37. Sleep Function screen.
• Use the Right and Left Arrow keys to change the time before the LCD enters sleep mode.
• Press Enter to select. The LCD returns to the User Preferences screen.
3.11 The Pulse Trac™ System
The Gene Pulser Xcell uses the Pulse Trac waveform delivery system to generate the most accurate exponential
decay pulses possible for optimal cell transformation. Pulse Trac accurately calculates the time constant and
amplitude of each pulse based on what is actually delivered to the sample. However, more importantly, the
Pulse Trac system compensates for amplitude changes caused by varying sample resistances and improves
the accuracy of the low voltage capacitors. This provides:
• Sample conductivity measurement integrated with pulse output for true waveform delivery for samples
with resistance in the 10–1000 ohm range;
• Internal calibration and circuit monitoring program for accurate pulse delivery throughout the lifetime
of the unit;
• Time constant and voltage amplitude measurements to allow pulse delivery verification.
3.11.1 Pulse Trac System Description
The Pulse Trac system monitors and adjusts for the internal system resistance used to limit current
and the sample resistance in the cuvette. Sample resistance depends on its conductivity, the
distance between the electrodes in the cuvette, and the volume of media within the cuvette. Pulse
Trac circuitry monitors the resistance of the sample and delivers the desired voltage regardless of
sample volume or conductivity. When you are optimizing electroporation with the Pulse Trac sys-
tem, the electrical variables are controlled with exacting precision so that your results reflect only
the biological variables in your experimental design. This Pulse Trac diagnostic algorithm examines
the complete electrical circuit and electronically selects the right combination of capacitors to
deliver the most accurate and reproducible pulse for optimal and consistent electroporation over
the lifetime of the unit.
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