NPI EXT-10C Operating instructions

OPERATING INSTRUCTIONS AND
SYSTEM DESCRIPTION FOR THE
EXT-10C
EXTRACELLULAR AMPLIFIER
MODULE FOR EPMS SYSTEMS
VERSION 2.0
npi 2012
npi electronic GmbH, Bauhofring 16, D-71732 Tamm, Germany
Phone [phone]; Fax: [phone]
[email protected]; http://www.npielectronic.com

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Table of Contents
1. Safety Regulations............................................................................................................ 3
2. EPMS-07 Modular Plug-In System.................................................................................. 4
2.1. Components of the EPMS-07 Housing ....................................................................... 4
2.2. General System Description / Operation..................................................................... 4
2.3. EPMS-E-07 Housing ................................................................................................... 4
2.4. System Grounding ....................................................................................................... 5
2.5. Technical Data.............................................................................................................5
3. EXT-10C .......................................................................................................................... 6
3.1. EXT-10C Components ................................................................................................ 6
3.2. System Description...................................................................................................... 6
3.3. Signal Flow Diagram................................................................................................... 6
3.4. Description of the Front Panel..................................................................................... 7
3.5. Headstage .................................................................................................................... 9
Headstage Elements..................................................................................................... 9
3.6. Operation ..................................................................................................................... 9
4. Literature .......................................................................................................................... 11
Technical Data......................................................................................................................... 12

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1. Safety Regulations
VERY IMPORTANT:Instruments and components supplied by npi electronic are NOT
intended for clinical use or medical purposes (e.g. for diagnosis or treatment of humans),
or for any other life-supporting system. npi electronic disclaims any warranties for such
purpose. Equipment supplied by npi electronic must be operated only by selected,
trained and adequately instructed personnel. For details please consult the GENERAL
TERMS OF DELIVERY AND CONDITIONS OF BUSINESS of npi electronic, D-71732
Tamm, Germany.
1) GENERAL: This system is design ed for use in scientific laboratories and m ust be
operated only by trained staff. General safety regulations for operating electrical devices
should be followed.
2) AC MAINS CONNECTION: While working with the npi systems, always adhere to the
appropriate safety m easures for handling el ectronic devices. Before using any device
please read manuals and instructions carefully.
The device is to be operated only at 115/230 Volt 60/50 Hz AC. Please check for
appropriate line voltage before connecting any system to mains.
Always use a th ree-wire line cord and a m ains power-plug with a p rotection contact
connected to ground (protective earth).
Before opening the cabinet, unplug the instrument.
Unplug the instrum ent when replacing the fu se or changing line voltage. Replace fuse
only with an appropriate specified type.
3) STATIC ELECTRICITY: Electronic equipm ent is sensitive to static discharges. Some
devices such as sensor inputs are equipped with very sensitive FET amplifiers, which can
be damaged by electrostatic charge and must therefore be handled with care. Electrostatic
discharge can be avoided by touching a gr ounded metal surface when changing or
adjusting sensors. Always turn power off when adding or removing modules,
connecting or disconnecting sensors, headstages or other components from the
instrument or 19” cabinet.
4) TEMPERATURE DRIFT / W ARM-UP TIME: All analog electron ic systems are
sensitive to temperature changes. Therefore, all electronic instruments containing analog
circuits should be used only in a warmed-up condition (i.e. after internal temperature has
reached steady-state values). In most cas es a war m-up period of 20-30 m inutes is
sufficient.
5) HANDLING: Please p rotect the d evice from moisture, h eat, radiation and corrosive
chemicals.

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2. EPMS-07 Modular Plug-In System
2.1. Components of the EPMS-07 Housing
The following items are shipped with the EPMS-07 housing:
 EPMS-07 cabinet
 Power cord
 Fuse 2 A / 1 A, slow
 Front covers
2.2. General System Description / Operation
The npi EPMS-07 is a m odular system for processing of bioe lectrical signals in
electrophysiology. The system is housed in a 19” rackmount cabinet (3U) containing a power
supply and has room for up to 7 plug-in units. The plug-in units are connected to power by a
bus at the rear panel.
The plug-in units m ust be kept in position by four screws (M 2,5 x 10). The screws are
important not only for m echanical stability but also for prope r electrical connection to the
system housing. Free area must be protected with covers.
In order to avoid induction of electrom agnetic noise the power supply unit, the power switch
and the fuse are located at the rear of the housing.
2.3. EPMS-E-07 Housing
The EPMS-E-07 housing is designed for low-noi se operation, especially for extracellular
amplifiers and filters which ar e plugged in. I t operates with an exte rnal power su pply to
minimize distortions of the signals caused by the power supply.
The external power supply PWR-03D supports up to 3 EPMS-E housings and each housing is
connected to the rear panel of the EPMS-E-07 by means of an 6-pole cable. An LED indicates
that the PWR-03D is powered on. P ower switch, voltage selector and fuse are located at the
rear panel.
Figure 1: PWR-03D front panel view

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Figure 2: PWR-03D rear panel view
Note: This power supply is intended to be used with npi EPMS-E systems only.
2.4. System Grounding
The 19" cabinet is grounded by the power ca ble through the ground pin of the m ains
connector (= protective earth). In order to avoid ground loops th e internal ground is isolated
from the protective earth. The internal gr ound is used on the BNC connectors or G ROUND
plugs of the m odules that are inserted in to the EPMS-07 housing. The internal ground and
mains ground (= protective earth) can be conne cted by a wire using the ground plugs on the
rear panel of the instrument. It is not possible to predict whether measurements will be less or
more noisy with the internal ground and mains ground connected. We recommend that you try
both arrangements to determine the best configuration.
2.5. Technical Data
19” rackmount cabinet, for up to 7 plug-in units
Power supply: 115/230 Volts AC, 60/50 Hz, fuse 2 A / 1 A slow, 45-60 W
External power supply (for EPMS-E): 115/230 Volts AC, 60/50 Hz, fuse 1.6/0.8 A, slow
Dimensions: 3U high (1U=1 3/4” = 44.45 mm ), 254 mm deep (with high voltage power
supply: 354 mm deep)

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3. EXT-10C
3.1. EXT-10C Components
The following items are shipped with the EXT-10C system:
 Amplifier module for the EPMS-07 system
 GND- (2.6 mm banana plug) and REF. (SMB) connectors for headstage
 Headstage
 User manual
3.2. System Description
The EXT-10C was designed for perform ing low noise recordings of small extracellular
signals in slices or in in vivo preparations using fine tipped glass or m etal microelectrodes.
The system consists of a module for the npi EPMS-07 modular system and a small headstage
with a holding bar.
The EXT-10C has a differential input with high input resistance for minimizing noise and the
incoming signal can be compensated for offset and capacity of the microelectrode by the two
potentiometers OFFSET and C-COMP. An anal og balance m onitor makes the control of
offsets easy. The recorded signal can be obtai ned either AC with GAIN of 100, 1k or 10k or
DC with GAIN of 10, 100 or 1k. An optional NOTCH filter eliminates 50/60 Hz noise in AC
measurements.
The EXT-10C is designed to be used with the DPA-2F pr eamplifier/filter module from npi
which combines additional gain stages with high- and lowpass filters.
3.3. Signal Flow Diagram
The signal is passed through the EXT-10C as shown below.

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3.4. Description of the Front Panel
Figure 3: EXT-10C front panel view
In the following description of the front panel elements each elem ent has a number tha t is
related to that in Fi gure 3. The number is followed by th e name (in uppercase letters) written
on the front panel and the type of the element (in lowercase letters). Then, a short description
of the element is given.
(1) HEADSTAGE connector
The HEADSTAGE cable is connected to the unit at an 8-pin connector in the center
of the module.
(2) DC OUTPUT connector
BNC connector providing the am plified signal DC coupled. The a mplification factor
is set by the GAIN DC switch (3). The DC OUTPUT is always unfiltered.

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(3) GAIN DC switch
Switch to set the GAIN of the outgoing DC signal. Three GAIN factors are
available: x10, x100 or x1k.
(4) C-COMP. potentiometer
Control for com pensation of stray capaciti es of the m icroelectrode (10 turn
potentiometer, range 0-20 pF). Due to the positive feedback circuit
overcompensation of the capacity will lead to oscillations which may damage the
cell.
(5) POTENTIAL x10 meter
The analog POTENTIAL monitor displays the offset in the range of 30 mV
and is used for optimal cancellation of the OFFSET.
(6) –OVER +OVER LEDs
LEDs that indica te if the am plifier 10% below it’s positive or negative lim it
(±10 V). The linear range of the amplifier is 12 V.
(7) OFFSET potentiometer
10 turn potentiometer to compensate for the OFFSET of a DC signal.
Note: Position 5 on the OFFSET control corresponds to 0 mV offset.
(8) GAIN AC switch
Switch to set the GAIN of the outgoing AC signal. Three GAIN factors are
available: x100, x1k or x10k.
(9) AC OUTPUT connector
BNC connector providing the am plified signal AC coupled. The a mplification factor
is set by switch (8).
(10) NOTCH switch (optional)
Switch to set the NOTCH filter (50 Hz / 60 Hz ) or to bypass the NOTCH filter (switch
position OFF) for AC measurements.

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3.5. Headstage
Figure 4: electrode holder (optional) and headstage of the EXT 10-2F
Headstage Elements
1 PEL:BNC connector for the electrode holder (measuring electrode)
2 REF: SMB connector for the reference electrode
3 GND: Ground connector
4 Holding bar
On request, P EL can be im plemented using 1 mm or 2 mm banana jacks or using SMB
connectors.
Very Important: EXT 10C headstages are always labeled “EXT” (see Figure 4) and must not
be exchanged with headstages from npi electronic’s desktop EXT amplifiers, e.g. the EXT-2F
which is labeled “EXT-02”!
Also Important: The shield of the BNC connector of the headstage is connected to driven
shield, and must not be connected to ground.
3.6. Operation
Extracellular measurements are mostly done in slices or in vivo, where distortions of the
signal caused by other instrum ents and the animal itself are very co mmon. Additionally,
extracellular signals are very sm all and have to be a mplified enormously. The drawback is
that noise is amplified as well. Ther efore, the headstage of the EXT- 10C is equipped with a
differential input that m inimizes noise pick-up. Differential m eans, that the signal for the
amplifier is the difference between the positive ( +) (PEL) and negative (-) (REF.) input of the
headstage. This results in canceling of all signals which both electrodes record, e.g. noise.
For differential measurements, both inputs of the headstage (REF. and P EL) are connected to
microelectrodes using cables with grounde d enclosure or electrode holders. P EL is connected
to the measuring electrode and REF. to the re ference electrode. The experimental chamber is
grounded by an Ag-AgCl pellet (or an AGAR br idge) connected to G ND of the headstage
(see Figure 5).

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If differential m easurement is not required (single-ended measurement configuration, see
Figure 5), the REF inp ut must be connected to ground (GND). The amplifier is in an
undefined state, if the REF is left open, an d can go into saturation m aking reliable
measurements impossible.
Figure 5: headstage connections, A: differential measurement, B: single-ended measurement