WPI DAM50 Bedienungsanleitung
Instrumenting scientific ideas
WORLD
PRECISION
INSTRUMENTS
DAM50
Dierential Amplier
Serial No._____________________
www.wpiinc.com
INSTRUCTION MANUAL
092618
DAM50
World Precision Instruments i
CONTENTS
ABOUT THIS MANUAL ................................................................................................................... 1
INTRODUCTION .............................................................................................................................. 2
Parts list ...................................................................................................................................... 2
Unpacking................................................................................................................................... 2
INSTRUMENT DESCRIPTION ........................................................................................................ 3
The Amplier.............................................................................................................................. 3
Electrode Impedance............................................................................................................... 3
Filters............................................................................................................................................ 3
AC or DC Recording?................................................................................................................ 5
MAINTENANCE ................................................................................................................................ 5
Testing the Amplier ................................................................................................................ 5
SPECIFICATIONS.............................................................................................................................. 6
APPENDIX A DAM50 WIRING CONFIGURATIONS ................................................................... 7
A.300647 Prewired cable for metal electrodes................................................................. 7
a.Dierential conguration (Mode A-B) ......................................................................... 7
b.Single ended conguration (Mode A) ......................................................................... 7
B.5489 mini-banana adaptor for glass ................................................................................ 8
a.Dierential conguration (Mode A-B) ......................................................................... 8
b.Single ended conguration (Mode A) ......................................................................... 8
C.5447 2 mm adaptor for glass............................................................................................. 9
a.Dierential conguration (Mode A-B) ......................................................................... 9
b.Single ended conguration (Mode A) ......................................................................... 9
DECLARATION OF CONFORMITY ..............................................................................................10
WARRANTY .....................................................................................................................................11
Claims and Returns ................................................................................................................11
Repairs.......................................................................................................................................11
Copyright © 2018 by World Precision Instruments. All rights reserved. No part of this publication may
be reproduced or translated into any language, in any form, without prior written permission of World
Precision Instruments, Inc.
ii World Precision Instruments
DAM50
World Precision Instruments 1
ABOUT THIS MANUAL
The following symbols are used in this guide:
This symbol indicates a CAUTION. Cautions warn against actions that can cause
damage to equipment. Please read these carefully.
This symbol indicates a WARNING. Warnings alert you to actions that can cause
personal injury or pose a physical threat. Please read these carefully.
NOTES and TIPS contain helpful information.
Fig. 1—The DAM50 is a dierential amplier.
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INTRODUCTION
Dierential amplication is of great importance in bioelectric
recording to reduce the ever present eect of noise
interference from power line induction. A well designed
dierential amplier will signicantly diminish power line
(mains) noise. It is most essential that the preparation be
connected with an electrode to a good electrical ground
as well as to the grounding wire of the DAM50 itself. This
should have the eect of greatly reducing electrostatically
induced potential. In addition to the preparation ground,
two dierential input connections must be made via
appropriate electrodes applied to the recording site so as to
optimally record a bioelectric potential dierence.
Parts list
Contents
DAM50 amplier
3518 shielded cable (bare termination) (available in a package of two as P/N 3517).
300647 shielded cable for metal electrodes
Unpacking
Upon receipt of this instrument, make a thorough inspection of the contents and
check for possible damage. Missing cartons or obvious damage to cartons should be
noted on the delivery receipt before signing. Concealed damage should be reported
at once to the carrier and an inspection requested. Please read the section entitled
“Claims and Returns” on page 11 of this manual. Please contact WPI Customer
Returns: Do not return any goods to WPI without obtaining prior approval (RMA
# required) and instructions from WPI’s Returns Department. Goods returned
(unauthorized) by collect freight may be refused. If a return shipment is necessary,
use the original container, if possible. If the original container is not available, use a
suitable substitute that is rigid and of adequate size. Wrap the instrument in paper or
plastic surrounded with at least 100mm (four inches) of shock absorbing material. For
further details, please read the section entitled “Claims and Returns” on page 11 of
this manual.
DAM50
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INSTRUMENT DESCRIPTION
The Amplier
INPUT to the DAM50 amplier is made via a exible, 4-wire shielded cable terminated
in a miniature telephone-style plug. The DAM50 now has a prewired cable (300647)
made for metal electrodes (0.031” pin) and a reference electrode on a 2 mm pin. Refer
to the appendix for wiring congurations.
The designation of the four wires is indicated on the mating panel receptacle. The
INPUT SELECT switch allows the user to choose A, B (inverting) or dierential A-B.
It is recommended that, while the electrodes are being connected, amplier inputs
should be grounded with the INPUT SELECT switch to avoid input overload which may
result in excessive recovery time as described below. Further, inputs A and -B must
be connected to a ground return path. In A-B mode, if either input is not placed on
the preparation, it must be connected to ground. Note that in A or -B INPUT SELECT
modes, the input not selected is grounded internally. The recorder or oscilloscope is
connected via the cable provided to the OUTPUT connector on the right side of the
amplier case.
Amplication is controlled by the GAIN selector switch. Note that amplication is ten
times larger in the AC mode than in the DC mode.
Electrode Impedance
If electrodes of very high impedance are used, electrostatic induction will induce
objectionably large noise signals. It may then be necessary to enclose the electrode
and cable with an electrostatic shield (keep the cable length short) or alternatively to
shield the entire recording area (The DAM80, a companion instrument in the DAM
amplier series, is especially designed for high impedance electrode recording).
Filters
The LOW FILTER selector switch determines the lower cut o frequency when the user
is in the AC MODE. Note that at 0.1 Hz setting the amplier may take a long time to
recover if the user inadvertently disconnects an input wire or if the input is exposed
to an excessively large artifact. This is a typical property of AC ampliers set at very low
frequency lter settings. For fast recovery from signal overload the user is advised to
operate at the highest frequency setting of the low frequency lter consistent with the
application. Generally, slow signals such as ECG and EEG require the 0.1 Hz setting,
while nerve action potential recording allows the use of the 10 Hz LOW FILTER setting
without sacricing signal quality.
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Fig. 1—GAINS: This chart shows the standard 3dB frequency cuto at maximum
lter band pass.
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AC or DC Recording?
It should be noted that DC recording with metal electrodes will invariably result in
excessively large galvanic potentials being applied to the amplier’s input terminals.
This can result in overdriving the amplier so that the POSITION control will not be
able to restore the operating baseline’s position. In this case, use Calomel or Ag-AgCl
electrodes, or use an external variable bucking potential; alternatively, resort to AC
recording.
MAINTENANCE
Testing the Amplier
Instrument POWER is provided by two alkaline 9 volt batteries. Battery operation
results in lower internal noise level. Batteries can be tested by activating the BAT/CAL
switch. If a short tone is heard, the batteries are functional. Conversely if the tone is
absent, the batteries must be replaced. An additional function that the BAT/CAL switch
performs is to provide a low frequency square wave test signal which is applied to the
amplier input. The amplitude of this signal is 100 microvolts when operating in either
of the two highest GAIN positions and 1 millivolt in the lowest GAIN position.
Mode Gain Cal signal Output
DC 10× 1 mV 10 mV
DC 100× 1 mV 100 mV
DC 1000× 100 µV 100 mV
AC 100× 1 mV 100 mV
AC 1000× 1 mV 1000 mV
AC 10,000× 100 µV 1000 mV
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SPECIFICATIONS
This unit conforms to the following specications:
Input Resistance ...............................................>1012 Ohms, common mode and dierential
Input Leakage Current .................................................................................................50 pA, max.
Amplication ....................................................................................... 100×, 1000×, 10,000× (AC)
........................................................................................................................10×, 100×, 1000× (DC)
Common Mode Rejection Ratio (CMRR) .......................................... 100 dB typ. @ 50/60 Hz,
..............................................................................................................................80 dB typ. @ 1 KHz
Equivalent Noise Signal Input (ENSI) ..............................................................................................
AC amplier (typ.)............................................................... 0.4 µV rms (2.0 µV p/p), 0.1-100 Hz
................................................................................................2.0 µV rms (10 µVp/p), 1 Hz-10 kHz
DC Amplier .............................................................................6.0 µV rms (30 µV p/p), 3-10 kHz
Bandwidth Filter Settings ..................................................................................................................
AC ................................................................................................low frequency 0.1, 1, 10, 300 Hz
AC and DC .......................................................................... high frequency 100 Hz, 1, 3, 10 KHz
Position .................................................................................................................................... 250mV
Output Voltage Swing............................................................................................................... ± 8 V
Output Resistance...........................................................................................................470 Ohms
Battery Test.................................................................................................1 second audible tone
Calibrator Signal.........................................10 Hz square wave, amplitude 100 µV (at 1000×
.................................................................................. and 10,000×), 1 mV (at 100×) and 10× DC).
Power.......................................................................................... 2 9V alkaline batteries, supplied
Input Cables........ 1 shielded cable with metal electrode connectors are provided and 1
shielded cable with bare wires.
APPENDIX A DAM50 WIRING CONFIGURATIONS
PART NUMBER DESCRIPTION
M3301EH Replacement Electrode Holder
M3301R Manual Micromanipulator
MD4R Dual Tool-Holder Micromanipulator
TM31A10 Tungsten Metal Electrodes Prole A, 76 mm, 1 micron
RC1T Reference Cells
M10 M10 Magnetic Stand
5052 Steel Base Plate, 10 lbs
3294 Ground Wire for DAM80 Probe
EP2 Ag/AgCl Electrode
2505 Electrode Handle 6.3 mm
5444 Electrode Handle 4.8 mm
13620 Low-noise cable for Microelectrode Holder
5489 Optional Probe for DAM50
MEH7W-10 Microelectrode Holder
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