A-MSystems 2400 User manual

INSTRUCTION MANUAL
FOR
PATCH CLAMP AMPLIFIER
MODEL 2400
Version 14.0
March 2020
A-M Systems, Inc.
PO Box 850
Carlsborg, WA 98324
U.S.A.
360-683-8300 . 800-426-1306
FAX: [phone]
http://www.a-msystems.com
Each Patch Clamp Amplifier is delivered
complete with:
A headstage probe (purchased separately)
Model Cell
5” Model Cell connector cable
Rack Mount Hardware

Disclaimer
THIS EQUIPMENT IS NOT
INTENDED FOR USE WITH
HUMAN SUBJECTS IN ANY
WAY.
Document
The information contained in
this manual was as accurate as
possible at the time of
publishing, but is subject to
change without notice and
should not be construed as a
commitment by A-M Systems,
Inc. Changes may have been
made to the hardware or
firmware it describes since
publications. A-M Systems,
Inc. reserves the right to change
specifications as required. For
the latest information please
check our website
(http://www.a-msystems.com)
or contact A-M Systems, Inc.
directly.
Manual Product Number
880004
Manual Document Number
5027600 Rev 14
All rights reserved. No part of
this document may be
reproduced by any means
without the prior written
permission of A-M Systems,
Inc.
Safety
This instrument is provided with
terminal for protective grounding.
Before applying power, verify that
the correct safety precautions are
taken (see the following warnings).
In addition, note the external
markings on the instrument that are
described under Safety
Symbols. Do not operate the
instrument with its cover removed.
Replace fuse only with specified
type.
Supply Voltage
This equipment is customized at
the factory for line voltages of the
county of destination. The required
line voltage is indicated on the rear
panel.
WARNING
Do not attach a line voltage that
does not match the line voltage
specified on the rear panel.
Before turning on the instrument,
you must connect the protective
earth terminal of the instrument to
the protective earth conductor of
the (mains) power cord. The mains
plug must only be inserted in a
socket outlet with a protective earth
contact.
Service should be performed by
trained personnel only. To avoid
dangerous electric shock, do not
perform any service unless
qualified to do so.
Do not operate the instrument in
the presence of flammable gases or
fumes. Operation of any electrical
instrument in such an environment
constitutes a definite safety hazard.
Safety Symbols
The product is marked with this
symbol when it is necessary for
you to refer to the instruction
manual in order to protect
against damage to the product.
WARNING
The Warning symbol calls
attention to a procedure or
practice, which, if not correctly
performed could result in
injury. Do not proceed beyond
a Warning symbol until the
indicated conditions are fully
understood and met.
CAUTION
The Caution symbol calls
attention to a procedure or
practice, which, if not correctly
performed could result in
damage to the product. Do not
proceed beyond a caution until
the indicated conditions are
fully understood and met.

Table of Contents
Table of Contents....................................... iv
List of Tables and Figures........................... v
About This Manual ..................................... 1
Chapter Overview................................... 1
Conventions ............................................ 1
Quick Overview.......................................... 2
Getting Started ............................................ 4
Basic Connections................................... 4
Functional Test........................................ 5
Single Channel Recordings..................... 6
Whole Cell Recordings......................... 11
Current Clamp Recordings ................... 17
Instrument Operation ................................ 20
Probe..................................................... 20
Power .................................................... 21
Meter..................................................... 21
Mode..................................................... 22
Capacity Compensation........................ 24
Fixed Outputs........................................ 24
Whole Cell Compensation.................... 25
Series Resistance................................... 25
Clamp Signal......................................... 27
Probe Input............................................ 29
Bandwidth............................................. 29
Bath Input.............................................. 30
Telegraph Outputs................................. 30
AC Power Input .................................... 32
Model Cell ............................................ 32
Connecting to a Computer........................ 33
Troubleshooting........................................ 34
Circuit Description.................................... 36
Probe..................................................... 36
Clamp Signal......................................... 36
Current Clamp....................................... 36
Membrane Voltage Output ................... 37
Compensation ....................................... 37
Specifications............................................ 38
Input Impedance.................................... 38
Output Impedance................................. 38
Input Current/Voltage ratings ............... 38
Probe Gain and Bandwidth................... 38
Probe Case ............................................ 38
Maximum Instrument Noise................. 39
Internal Bandwidth................................ 39
Membrane Current Output Range......... 39
Membrane Voltage Output Range........ 39
Filter...................................................... 39
RMS Meter............................................ 39
Capacity Compensation........................ 39
Whole Cell Compensation.................... 40
Series Resistance................................... 40
DC Balance........................................... 40
Hold Command..................................... 40
Offset Command................................... 40
Speed Test Command........................... 40
Vcomp Command................................. 40
Iresist Command................................... 40
External Command: Voltage Clamp..... 41
External Command: Current Clamp ..... 41
Power Supply Requirements................. 41
Physical Dimensions............................. 42
Powered Probe Input............................. 42
Warranty ................................................... 43
Index ......................................................... 45

A-M Systems, Inc.
131 Business Park Loop, PO BOX 850, Carlsborg, WA 98324 USA
Telephone: [phone] * 360-683-8300 * FAX: [phone]
E-mail: [e-mail] * Website: http://www.a-msystems.com
List of Tables and Figures
Figure 1. Model Cell Schematic ................. 7
Figure 2. Electrode in the air....................... 8
Figure 3. Electrode in the bath.................... 8
Figure 4. Offset adjustment trace................ 9
Figure 5. Patch seal trace .......................... 10
Figure 6. Patch seal with transients
compensated...................................... 10
Figure 7. Whole cell recording before
capacity compensation...................... 14
Figure 8. Whole cell recording with fast
transients cancelled........................... 14
Figure 9. Whole cell recording with all
transients cancelled........................... 14
Figure 10. Whole cell recording with series
resistance controls turned on to 90% 15
Figure 11. The Probe................................. 20
Figure 12. Power switch ........................... 21
Figure 13. Meter........................................ 21
Figure 14. Mode........................................ 22
Figure 15. Probe Gain............................... 23
Figure 16. Filter ........................................ 23
Figure 17. Gain ......................................... 23
Figure 18. Mode Output............................ 24
Figure 19. Capacity Compensation........... 24
Figure 20. Fixed outputs ........................... 24
Figure 21. Whole Cell Compensation....... 25
Figure 22. Whole cell recording before
compensation .................................... 25
Figure 23. Whole cell recording after whole
cell compensation.............................. 25
Figure 24. Series Resistance controls ...... 25
Figure 25. Voltage clamp series resistance
controls.............................................. 26
Figure 26. Whole cell recordings with RsPre
at 90% ............................................... 26
Figure 27. Whole cell recordings with
RsComp at 90% ................................ 26
Figure 28. Whole cell recording with
RsComp and RsPre at 90%............... 27
Figure 29. Whole cell recording with
RsComp and RsPre at 90% and Whole
Cell parameters readjusted................ 27
Figure 30. Current clamp Bridge Balance27
Figure 31. Hold and Offset command
control ............................................... 27
Figure 32. Tracking Controls................... 28
Figure 33. Command Filter...................... 28
Figure 34. External Command input........ 28
Figure 35. Probe input.............................. 29
Figure 36. Bath Input............................... 30
Figure 37. Telegraph Outputs.................. 30
Figure 38. AC Power Input..................... 32
Figure 39. Model Cell.............................. 32
Figure 40. Model 2400 Block Diagram... 35
Figure 41. Probe block diagram............... 36
Table 1 Typography Conventions............... 1
Table 2 Minimal equipment........................ 4
Table 3 Front panel test settings ................. 5
Table 4 Typical noise levels ....................... 6
Table 5 Single channel set-up..................... 7
Table 6 Probe Gain and Bath VClamp ....... 9
Table 7 Whole Cell set-up ........................ 12
Table 8 Current clamp set-up.................... 17
Table 9 Probe resistor values.................... 19
Table 10 Probe resistor values.................. 20
Table 11 Probe Pin-out ............................. 21
Table 12 Meter Display settings ............... 22
Table 13 Probe resistor current gain......... 23
Table 14 Mode output units...................... 24
Table 15 External Clamp Signal Scaling.. 29
Table 16 Noise telegraph output............... 30
Table 17 Gain telegraph output................. 30
Table 18 Filter telegraph output................ 31
Table 19 Mode telegraph output............... 31
Table 20 Error telegraph output................ 32
Table 21 Common Problems .................... 34

A-M Systems, Inc.
1
131 Business Park Loop, PO BOX 850, Carlsborg, WA 98324 USA
Telephone: [phone] * 360-683-8300 * FAX: [phone]
E-mail: [e-mail] * Website: http://www.a-msystems.com
About This Manual
Chapter Overview
This manual is designed to provide the researcher with the basic features of
Model 2400 in order to proceed to experiments as quickly as possible. For this
reason we have left the detailed descriptions of each function towards the end of
the manual. Chapter 1 will review the instrument’s capabilities. Chapter 2 will list
the necessary steps to start collecting data, in each of the following situations:
single channel, whole cell, or current clamp mode. Chapter 3 provides
description of the amplifier’s features and controls. Chapter 4 describes how to
interface the Model 2400 with various software packages. Chapter 5 lists some
simple steps to identify and solve common problems encountered in
electrophysiological recording. Chapter 6 provides a description of the amplifier’s
circuitry.
Although this manual provides the basics on using our patch clamp amplifier, it
assumes the researcher has some knowledge of patch clamp techniques. For a
more in-depth discussion of patch clamp recording we refer you to “Single-
Channel Recording”, edited by Bert Sackmann and Erwin Neher (ISBN
030644870X, Plenum Press), and “Voltage and patch clamping with
microelectrodes” edited by Thomas G. Smith, Jr. et al. (ISBN 0683077732,
American Physiological Society).
Conventions
This manual uses certain conventions to indicate elements of the Model 2400’s
user interface. The following table shows some examples:
Named panel controls or
connectors Adjust OFFSET until Im reads zero on the oscilloscope.
Knobs within named outlined
area on the front panel follow
the outlined area after a colon
Set MODE:GAIN to 100, for an overall
gain of 10mV/pA
Values on the meter The meter should display 0.05 pA.
Dual knobs. (i) refers to the
inner knob and (o) refers to the
outer knob
Alternately adjust FAST2-GAIN(i) and
FAST2-LAG(o) until the transient is
minimized
Table 1 Typography Conventions

A-M Systems, Inc.
2
131 Business Park Loop, PO BOX 850, Carlsborg, WA 98324 USA
Telephone: [phone] * 360-683-8300 * FAX: [phone]
E-mail: [e-mail] * Website: http://www.a-msystems.com
1
Quick Overview
The Model 2400 is a low noise, full featured intracellular/extracellular amplifier
designed for voltage or current clamping using patch electrodes on single
channels or whole cells. Its unique design allows fast intracellular current clamp
measurements with sharp electrodes. Advanced circuit design techniques using
field programmable gate arrays eliminated noisy microprocessors.
Amplifier current gain is extremely flexible as it can accept any of four switchable
resistive feedback probes. Each probe has two feedback resistors selected from
the following values: 10M, 100M, 1G, and 10G. The main amplifier automatically
recognizes the feedback resistor and adjusts internal gains to always provide the
correct values to the meter and correct signal magnitude at the outputs. The wide
range of feedback resistors means currents from 1 fA to 1 µA can be recorded
with outputs of 1mV/nA to 10mV/fA.
Unlike most patch clamp amplifiers, the Model 2400 has a voltage follower in the
probe. This allows this amplifier to be a true fast current clamp amplifier with no
instability. An integrated 6 position four pole low pass Bessel filter provides
flexible signal conditioning. Dual fine tuning capacity compensation is available
to eliminate virtually all electrode-induced transients. Calibrated whole cell
compensation provides easy display of membrane capacitance and access
resistance.
A host of command potentials are integrated internally within the model 2400,
including an automatic tracking command to zero the membrane current, manual
controls for offset and holding potentials, and an easily readable digital display.
For signals that are more complicated, an external command input with different
scaling factors is available for use with any signal source.

A-M Systems, Inc.
3
131 Business Park Loop, PO BOX 850, Carlsborg, WA 98324 USA
Telephone: [phone] * 360-683-8300 * FAX: [phone]
E-mail: [e-mail] * Website: http://www.a-msystems.com
Standard stimulation protocols are integrated into the MODE switch. Membrane
voltages can be monitored in 3 modes: Iclamp, Iresist, and Ifollow. Iclamp
is the generic current clamp mode where clamp signals can be customized using
the front panel controls or via the external clamp input. Iresist sends a fixed
amplitude square wave for easy measurement of electrode resistance. Ifollow
configures the probe to be a simple voltage follower to monitor membrane
voltage. Currents can be monitored in 3 modes: Vcomp, Vclamp, and Vtest.
Vcomp is a voltage clamp mode with a fixed amplitude square wave clamping
signal, useful for searching for cells and adjusting the compensation controls.
Vclamp is the generic voltage clamp mode where clamp signals can be
customized using the front panel controls or via the external clamp input. VTest
sends a square wave of current into the probe for testing the frequency response
of the probe.
A digital meter provides accurate values of command signals and membrane
currents or voltages, the true RMS noise of the amplifier and experimental setup,
the cut off frequency of the low pass filter, and the overall gain of the amplifier
plus probe.
Series resistance compensation provides the researcher with the option of
introducing either or both predictive and corrective compensation from zero to
100%. Fine and coarse controls for lag provide sensitive control to minimize
oscillation produced by compensation close to 100%.
Separate compensation controls exist for eliminating transients seen during
current clamp experiments when the bridge balance is used.
Telegraph outputs provide analog voltage equivalents of front panel settings
including error conditions, amplifier mode and gain, Cmembrane, RMS noise, and
low pass filter cut-off value. These telegraphs allow the Model 2400’s front panel
settings to be automatically recorded by your system software.
For those who need extra large bandwidths, the raw bandwidth of the entire
amplifier may be adjusted via a rear panel potentiometer.
A second powered probe input is available for use as a bath signal input.

A-M Systems, Inc.
4
131 Business Park Loop, PO BOX 850, Carlsborg, WA 98324 USA
Telephone: [phone] * 360-683-8300 * FAX: [phone]
E-mail: [e-mail] * Website: http://www.a-msystems.com
2
Getting Started
Patch clamp amplifiers can seem complicated. This chapter is designed to take
you through an experiment with the minimal amount of instructions necessary. If
you are familiar with patch clamp recording already, you may want to skip ahead
to Chapter 3 where each feature of the Model 2400 is described.
When you receive your Model 2400 confirm that everything in the packing list is
included. Make sure there are no obvious signs of internal damage, such as
rattling. Pick up the amplifier and tilt in gently from side to side, and listen for
anything that might be loose.
Check that the correct voltage for your country is shown on the back of the unit.
The Model 2100 should be delivered with the appropriate mains power voltage
set, at either 100-120 volts or 220-240 volts. The setting is indicated on the back
panel to just to the side of the power input. If the wrong voltage or no voltage is
indicated on the rear panel contact A-M Systems, Inc. immediately
In this chapter you will need the equipment listed in the following table.
A-M Systems, Inc. Model 2400 Patch Clamp Amplifier
A-M Systems, Inc. Model Cell
An oscilloscope
Basic Connections
Connect the power cable to the AC POWER INPUT on the rear of the unit and
to an approved outlet. Do not turn the Model 2400 on. Connect the probe cable
to the PROBE input on the rear of the unit. Connect a BNC cable from the
MODE OUPUT to an oscilloscope.
Be certain to properly ground yourself whenever you handle the probe as it is
susceptible to electric static discharge (ESD). ESD can cause immediate or subtle
damage to sensitive electronic parts. You can reduce the chances of ESD damage
by:
·Only connecting the probe to the amplifier when the amplifier is off.
·Always grounding yourself by touching the handle of the amplifier, or
another grounded piece of metal prior to handling the probe.
·Avoiding extraneous walking around while holding the electrode holder
or model cell, especially if you are on carpet or during conditions of low
temperature and low humidity.
Table 2Minimal equipment
WARNING
CAUTION

A-M Systems, Inc.
5
131 Business Park Loop, PO BOX 850, Carlsborg, WA 98324 USA
Telephone: [phone] * 360-683-8300 * FAX: [phone]
E-mail: [e-mail] * Website: http://www.a-msystems.com
Functional Test
This simple test will check to see if the most essential components of the
amplifier are working.
With the amplifier turned off, set the front panel controls as follows:
METER (knob) Noise
MODE Vclamp
MODE PROBE GAIN LOW
MODE: GAIN 1
MODE: FILTER Open
CAPACITY COMPENSATION: FAST1: Gain Fully counterclockwise
CAPACITY COMPENSATION: FAST1: Lag Fully counterclockwise
CAPACITY COMPENSATION: FAST2 Fully counterclockwise (inner and outer knob)
WHOLE CELL COMPENSATION OFF
SERIES RESISTANCE OFF
CLAMP SIGNAL (Hold/Offset Toggle) OFF
CLAMP SIGNAL: 3kHz OFF
CLAMP SIGNAL (tracking) OFF
CLAMP SIGNAL: EXTERNAL OFF
Place the probe in a Faraday cage (this can be as simple as surrounding the probe
with aluminum foil and grounding the foil). Note: the BNC shields on the front
panel make good ground connectors.
Depress the Power switch.
The power switch should light up and the meter should display the noise value.
Step the FILTER knob counterclockwise through the decreasing cut-off
frequency positions and the noise value should drop. Select the 1.0kHz position.
The meter now displays the RMS noise at 1kHz.
Switch the PROBE GAIN between HIGH and LOW. You should see the noise
value on the meter alternate between two different values. The values will depend
on the type of probe you have. The following table gives expected values of
noise for each type of feedback resistor. At any time, you can change METER to
GAIN, and MODE: GAIN to 1, then the meter will display the current gain of
the probe. You can then refer to the table to determine the value of resistor in
each PROBE GAIN setting.
Table 3Front panel test settings