NPI SEC-05LX, Operating Instructions Manual

Page: 66 / 69

SEC-EXT Headstage for Extracellular Recordings
with npi SEC Systems
The SEC-EXT headstage extends the range of operation of SEC amplifiers to the field of extracellular
recordings. It has a differential high impedance input stage with capacity compensation for the non-
inverting input (+ INPUT) and a gain of ten. This input stage is followed by a high pass filter with six
corner frequencies (1; 3; 10; 30; 100; 300 Hz).

DC output (POTENTIAL OUTPUT of the SEC): The direct output is connected to the
"POTENTIAL" channel of the SEC system, i.e. the signal is passed through the OFFSET
compensation stage, magnified by ten and filtered by the POTENTIAL FILTER. The overall gain
for the DC output is 100 (x10 input stage, x10 SEC potential magnification).

AC output (high pass output, CURRENT OUTPUT of the SEC): The output of the high pass filter
stage is fed into the "CURRENT" channel of the SEC system, i.e. it is passed through the
CURRENT OUTPUT SENSITIVITY stage where it is amplified (overall gains 10; 20; 50; 100;
200; 500; 1000). The amplified signal is filtered by the CURRENT FILTER.
Important: The SEC system must be in BRIDGE (B) mode. All inputs must be turned off or
disconnected. The BRIDGE balance control must be on 000 to avoid incoming disturbances.
The following systems and front panel elements are working:
CAP. COMPENSATION
Capacity compensation control for the non-inverting (+) input
POTENTIAL OUTPUT
DC output (x100)
OFFSET Offset control for the DC output
POTENTIAL FILTER Low pass Bessel filter for the DC output
POTENTIAL DISPLAY Shows electrode potential x10 (100 are 10 mV)
CURRENT OUTPUT
AC (high pass) output (x10...x1000)
CUR. OUTPUT Gain stage (10-1000) for the AC output
SENSITIVITY
CURRENT FILTER
Low pass Bessel filter for the AC output
OSCILLATION
as described in the SEC manual
SHUTOFF
PENETRATION "BUZZ" as described in the SEC manual (+I
max
/-I
max
do not work)
Important: This headstage is sensitive to static discharges. It is equipped with very sensitive FET
amplifiers, which can be damaged with electrostatic charge and must therefore be handled with care.
Damage can be avoided by touching a grounded metal surface when changing or adjusting the
electrodes. If a headstage is not used the input should always be connected to ground (either using an
appropriate connector or with aluminum foil wrapped around the headstage).
Always turn power off
when connecting or disconnecting headstages from the 19" cabinet .