PC-505B Manual, Rev. 201013
Warner
Instruments
A Harvard Apparatus Company
48
Glossary
A/D converter
– Analog to Digital converter. Computers are inherently digital while the voltage or current
output from an amplifier is analog. Therefore, a signal must be first converted to a digitized form before
a computer or its software can accept it. Desirable features in an A/D converter include rapid signal
conversion, small-step resolution and low noise.
analog
– Continuous or non-discrete. Often dynamically varying.
Compare to:
digital.
bandwidth
– The range of frequencies a device is capable of processing with minimal distortion. A
bandwidth of 1 Hz indicates that the device can faithfully process a signal occurring once per second
(1 Hz). The larger the bandwidth, the faster the device.
Bessel filter
– A device used to attenuate the high frequency components of a signal. The cutoff frequency
of a filter is normally defined as the frequency at which the amplitude of the signal is attenuated by 3
dB. A higher order filter (i.e., 8-pole
vs
. 4-pole) will attenuate the high frequency components more
rapidly. An 8-pole Bessel filter attenuates at 14 dB per octive.
BNC
connector
– A type of connector used to connect coaxial cables to high frequency electronic
equipment.
CAP COMP
–
See:
capacity compensation.
capacitance
– A capacitor can be represented by a small break in a conducting pathway bounded by two
parallel plates. The electric field generated across the space between the plates in the presence of an
applied voltage maintains a charge
density on each plate. The numerical measure of a capacitor’s
ability to maintain charge separation at a given potential is its capacitance. Capacitors effectively block
DC currents while passing AC currents. Has units of Farad (F).
capacity compensation
– The process wherein the current generated when charging a capacitor is
subtracted (or compensated) from the output signal.
channel conductance
–
See:
unitary channel conductance
chassis ground
– A connection used to link the amplifier chassis to an external potential.
circuit ground
– The potential to which all other potentials within the circuit are referenced. Also, a
connection used to link the reference potential of the amplifier circuit to an externally defined potential.
CMD IN
– Command Input. An external input into the amplifier
allowing the application of user defined
command voltages to the headstage. Connection is usually via BNC.
command sensitivity
– Selectable scaling of
CMD IN
input. Attenuation values of
CMD IN
are
x0.1
,
x0.01
,
and
x0.001
.
command voltage
– The voltage applied to the headstage resulting in a desired transmembrane potential
in the system under study.
control blocks
– Organization of controls on the amplifier into functional groups. Blocks are delineated by
titled blue boundaries.
