World Precision Instruments A365 Instruction Manual
Instrumenting scientific ideas
WORLD
PRECISION
INSTRUMENTS
A365
Stimulus Isolator
Serial No._____________________
www.wpiinc.com
INSTRUCTION MANUAL
082318
WARNING! High voltages produced can produce dangerous electrical
shock. This device is not approved for clinical applications. Do not turn on
power while you are holding bare high voltage wires or connectors.
A365
World Precision Instruments i
CONTENTS
ABOUT THIS MANUAL ................................................................................................................... 1
INTRODUCTION .............................................................................................................................. 2
Parts List ...................................................................................................................................... 2
Unpacking ................................................................................................................................... 3
INSTRUMENT DESCRIPTION ........................................................................................................ 4
Controls ....................................................................................................................................... 4
Audible Alarms ........................................................................................................................... 4
OPERATING INSTRUCTIONS ......................................................................................................... 5
Electrode connections ............................................................................................................. 6
Microstimulation ....................................................................................................................... 6
Normal Stimulation .................................................................................................................. 7
Biphasic Currents (bipolar) ..................................................................................................... 7
Electrolysis ................................................................................................................................. 7
Viewing the current pulses ..................................................................................................... 8
Monitoring Current on a Data Acquisition system (Lab-Trax 4/16) .............................. 8
Monitoring Voltage on a Data Acquisition system (Lab-Trax 4/16) .............................. 9
Constant Voltage Operation................................................................................................... 9
Instrument Case Grounding (Earthing) .............................................................................10
Electrode Exhauster ............................................................................................................... 10
Low Battery Indication ........................................................................................................... 10
MAINTENANCE ..............................................................................................................................11
Charging the NiMH Battery Stack (A365R) ........................................................................ 11
Full Charge or Partial Charge ...............................................................................................11
The A362 Charger ................................................................................................................... 11
Replace Batteries Annually ................................................................................................... 11
Changing the Batteries .......................................................................................................... 12
Procedure .................................................................................................................................12
Expected Battery Life ............................................................................................................. 12
TROUBLESHOOTING ...................................................................................................................13
Quick Instrument Test ...........................................................................................................13
Detailed Test ............................................................................................................................13
Calibration.................................................................................................................................14
SPECIFICATIONS ............................................................................................................................ 15
DECLARATION OF CONFORMITY .............................................................................................. 16
WARRANTY .....................................................................................................................................19
Claims and Returns ................................................................................................................19
Repairs ....................................................................................................................................... 19
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
A365
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 A365 Stimulus Isolator
2 World Precision Instruments
INTRODUCTION
The A365 is a specialized stimulus isolator for use in neuroscience and muscle studies.
Battery operated and electrically isolated from ground, its quiet internal control
circuitry minimizes artifacts and has very low leakage specications. Stimulus isolation
is needed to assure the precise localization of stimulus current and to prevent current
ow from the stimulation site to ground. Two models are available: A365D is powered
by sixteen 9-volt alkaline transistor batteries; A365R is powered by 16 rechargeable
NiMH (nickel metal hydride) 9-volt cells (A362 battery charger required). These
instruments can pulse repetitively at rates and durations controlled by front panel
controls and/or be optically pulsed or gated for time durations of a few microseconds
to DC, by any pulse generator, D-to-A or interface unit which can provide an adequate
output voltage equal to or greater than the threshold command levels specied
below.
Because current threshold is the most quantitatively reproducible parameter for
stimulation of nerve and muscle, all WPI stimulus isolators are designed to supply
constant current. Model A365 dispenses current reproducibly from its output
terminals, the amplitude being determined by the selected current range and the
setting of the % of Range dial. Current amplitude is “constant”, that is, load resistance
independent, provided that the I x R (load) product does not exceed the available
battery supply voltage. An audible alarm (the compliance alarm) will sound if I x R
reaches this limit. Model A365D can generate a voltage of 135V or more across its
output terminals. The amplitude of the current will be as dialed as long as the voltage
drop across the load (stimulus electrode path) does not reach the magnitude of the
supply voltage. The compliance alarm would then sound, signifying that (a) too much
current was dialed for a given load or (b) inter-electrode resistance was too high or
the electrode circuit path was open (see the Quick Instrument Test, below).
WARNING! High voltages produced can produce dangerous electrical shock.
This device is not approved for clinical applications. Do not turn on power
while you are holding bare high voltage wires or connectors.
WARNING! THIS DEVICE IS NOT INTENDED FOR HUMAN USE.
Parts List
After unpacking, verify that there is no visible damage to the sensor. Verify that all
items are included:
(1) A365 Stimulus Isolator
(1) Instruction Manual
A365
World Precision Instruments 3
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 19 of this manual. Please contact WPI Customer
Service if any parts are missing at 941.371.1003 or customerservice@wpiinc.com.
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 19 of
this manual.
INSTRUMENT DESCRIPTION
Controls
INPUT: An external command voltage level of approximately 5 volts (TTL)
applied to this connector enables current ow from the OUTPUT. Do not apply a
continuous DC input voltage greater than 9 volts.
4 World Precision Instruments
DC/TEST: Current can be manually generated by toggling this switch. MOM
(momentary) position allows push-release operation. ON provides a sustained DC
output on the output connectors.
AUDIO: When the AUDIO switch is on, an audible tone will sound whenever a
stimulus current is being generated. A higher pitched audible signal will also
sound, independent of the AUDIO switch, if the OUTPUT voltage amplitude
approaches that of the battery power stack (the “compliance alarm”). A low
frequency tone indicates the batteries need replacement or recharging.
MODE: When this switch is set on Bipolar, every pulse applied to the input
will cause the polarity of the output current to reverse. Thus, any sequence of
pulses applied results in alternating plus and minus current pulses at the output
terminals. In the O position, pulse polarity will be as indicated by the red polarity
lamps above the red and black output terminals.
POLARITY SELECT: A polarity reversing push button switch sets the red or black
OUTPUT terminal to be positive. The polarity lamps will toggle from red to black in
the bipolar mode as they are being switched.
RANGE: 0.1, 1 or 10 milliamperes can be selected as a maximum current.
% OF RANGE: This variable ten turn digital indicator control sets the exact current
amplitude as a percentage of the selected maximum current selected by the
Range switch. For ranges below 5% (05.0), it is recommended to use xed 0.1% test
resistors and a digital meter to set and check the required current values.
OUTPUT: Current output terminals. Output voltage depends on load resistance. An
audible warning sounds when the maximum load voltage occurs. When the Output
switch is O, the output terminals are disconnected from the circuitry.
POWER ON/OFF: Switch connects battery power to the isolator.
Turn the power switch o when instrument is not in use to avoid battery drain.
Audible Alarms
Audio on — This is a high frequency tone to indicate stimulation is present.
High tone with Audio o — compliance alarm, this indicates that the A365 cannot
supply enough voltage to drive the requested “dialed-up” current through the test
subject. This is usually an indication of a broken cable, electrode disconnection or a
misplaced electrode. Warning, the maximum high voltage is present on the banana
connectors.
Low tone — Battery low alarm; batteries require replacement or recharging. This
alarm turns on when the high voltage stack reaches 90 volts and depending on
the experiment’s current requirements the A365 may only supply power for a
short duration (less than half an hour at 10 mA with NiMH). This is at the 6.0 volt
threshold of the NiMH battery and rapid voltage decay in the battery cell occurs
Loading...