A365 www.wpiinc.com Stimulus Isolator INSTRUCTION MANUAL Serial No.
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.
Stimulus Isolator (A365) CONTENTS ABOUT THIS MANUAL ..................................................................................................................... 1 INTRODUCTION .................................................................................................................................. 2 Parts List ........................................................................................................................................... 2 Unpacking ..............................
iv World Precision Instruments
Stimulus Isolator (A365) 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.
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 specifications. Stimulus isolation is needed to assure the precise localization of stimulus current and to prevent current flow from the stimulation site to ground.
Stimulus Isolator (A365) 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.
INSTRUMENT DESCRIPTION Controls INPUT: An external command voltage level of approximately 5 volts (TTL) applied to this connector enables current flow from the OUTPUT. Do not apply a continuous DC input voltage greater than 9 volts. 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.
Stimulus Isolator (A365) 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).
OPERATING INSTRUCTIONS Operation of the A365 is controlled by applying an external voltage command to the input or by manually operating the DC/Test switch. Any source such as WPI’s DS8000, A300, A310 pulse generators or equivalent generator will be an appropriate source of command and trigger sync pulses for oscilloscope viewing of bioelectric responses.
Stimulus Isolator (A365) and the electrolyte. The capacitive value of this electrode can be characterized as 0.2 pF/μ2 at 1 Khz. This form of stimulation is best suited to neuroscience applications. Normal Stimulation For larger currents in excess of 1 mA that may be required for muscular stimulation, larger surface electrodes are to be used to distribute the larger currents. The use of silver-chloride surfaces (0.1 mm2 or larger) may be necessary.
Viewing the current pulses To view pulses of current on an oscilloscope it is first necessary to convert the current pulses to voltage pulses (see “Voltage”, below ) by using a dummy electrode pair. Therefore, connect a resistor of 1 K Ohm across the output terminals. Connect the two output terminals to the input of an oscilloscope. Oscilloscope settings: 200 mV per cm, vertical sensitivity, DC coupled and 1 millisecond per cm sweep speed.
Stimulus Isolator (A365) Fig. 2—Location of jumpers for the electrode exhauster circuit (shown disabled). Monitoring Voltage on a Data Acquisition system (Lab-Trax 4/16) To monitor the outputs as a current meter on the data acquisition system, use a shunt R resistor in series with the current flow along one of the electrodes (red connector). A 5 ohm resistor will drop 50 mV at 10 mA. The data conversion factor is 200×= 10mA A 50 ohm resistor will drop 500 mV at 10 mA.
Instrument Case Grounding (Earthing) The instrument case has not been connected to any part of the internal circuit of A365. To make a connection to the case, a spade lug and wire can be inserted under the head of any screw on the underside of the instrument case. This is useful in reducing noise in a Faraday cage environment. Electrode Exhauster The A365 is equipped with an electrode exhauster circuit.
Stimulus Isolator (A365) MAINTENANCE Charging the NiMH Battery Stack (A365R) To recharge the battery stack of an A365R, a companion charger, model A362, is designed to charge the A365’s batteries rapidly and safely. The charger cable plug inserts into the charging receptacle on the rear panel of the A365R isolator. Connect the charger’s power cord to the power line. The POWER switch on A365R must be OFF to enable charger operation.
usage, the batteries will operate satisfactorily for two months or more. Replace batteries when required or annually. Model A365R requires 16 Nickel-Metal Hydride 9-volt batteries (7.2 volt); type IEC-6F22 or equivalent is recommended. Alkaline batteries in model A365D cannot be replaced with NiMH rechargeable batteries as model A365D is not equipped for charging. Do not use the higher voltage 9.6.V rechargeable cells in this instrument. Procedure Turn the POWER switch to OFF.
Stimulus Isolator (A365) TROUBLESHOOTING Quick Instrument Test Switch Output to OFF, Range to 1 mA, DC/Test to OFF, Bipolar to OFF and AUDIO to ON. Turn POWER switch to ON. One red lamp above one of the output terminals should be lit. When the DC/Test switch is toggled to MOM, an audible tone should be heard (an externally applied +5 volt command applied to the input connector will have the same effect). Sound will cease when Test is OFF. Turn Audio OFF.
on position, output to positive. Place a digital voltmeter test leads on the output terminals. Apply the momentary switch and note the output voltage. Alkaline: An alkaline stack of batteries will measure in the 135 volt range (9V × 15). Alkaline 9V batteries can be discharged to approximately 5.0V per battery or 80V per stack of 16. However, replacement should be indicated at the 90V point to ensure longevity during a procedure.
Stimulus Isolator (A365) SPECIFICATIONS This unit conforms to the following specifications: Output Waveform ............................Current pulses or DC Output Polarity..................................Unipolar or electronically switched bipolar Output Current Ranges ..................0.1, 1.0 and 10 milliamperes Current Amplitude Error ................0.5 % of full scale, max. Current Resolution ...........................0.1% of full scale Output Load Voltage Range.........
DECLARATION OF CONFORMITY 16 World Precision Instruments
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Stimulus Isolator (A365) WARRANTY WPI (World Precision Instruments, Inc.) warrants to the original purchaser that this equipment, including its components and parts, shall be free from defects in material and workmanship for a period of one year* from the date of receipt. WPI’s obligation under this warranty shall be limited to repair or replacement, at WPI’s option, of the equipment or defective components or parts upon receipt thereof f.o.b. WPI, Sarasota, Florida U.S.A.
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