GRAS 12AB User manual

Instruction Manual
12AB 2-Channel Power Module for
GRAS Intensity Probes
LI0113 – 12 February 2008

CONTENTS
1. Introduction and Description ......................................3
1.1 Polarization Voltage ................................................3
1.2 PreamplierVoltageSupplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 PowerSupplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.4 Input/Output ......................................................4
2. External Features ................................................5
2.1 Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Rear Panel .......................................................7
3. Internal Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1 Battery Pack ......................................................8
3.2 User-servicableSwitches ............................................8
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.1 BatteriesandExternalPower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.2 PolarizationVoltageandPreamplierVoltage ............................9
5. Service and Repair ..............................................10
6. Specications ..................................................11

Intensity Power Module Type 12AB - Page 3
Fig. 1.1 Intensity Power Module Type 12AB
* FactorysettingsforusewithGRASSoundIntensityProbetype50AIversionB
1. Introduction and Description
TheG.R.A.S.IntensityPowerModuleType12AB(Fig.1.1)isatwo-channelpowersupplyfor
usewithversionsB,CandDoftheG.R.A.S.SoundIntensityProbeType50AI.
TheType12ABisbuiltintoasturdyanodizedaluminiumcabinetandcanbepoweredeitherby
internalstandardbatteriesoranexternalDCsupply(12V-18V),e.g.amains/lineadapter.
AblockdiagramofitsmaincomponentsisshowninFig.1.2.
1.1 Polarization Voltage
Thepolarizationvoltagecanbesettoeither0Vor200Vviaaninternalswitch(seesection3.2).
Theseare:
• 200V*—forusewithType50AI,or
• 0V—forprepolarizedmicrophones
1.2 PreamplierVoltageSupplies
Thepreampliervoltagesupplycanbesettoeither28VDCor120VDCviaaninternalswitch
(seesection3.2).Theseare:
• 120V*—formaximumdynamicrange,or
• 28V—forminimumpowerconsumption
1.3 Power Supplies
TheType12ABcanrunoninternalbatterieswithabatterylifeofapproximately10hoursusing
G.R.A.S.preampliers,orfromanexternalpowersupplyof12-18VDC,e.g.aG.R.A.S.
mains/lineadapterAB0002(Europe)/AB0003(USA).

Intensity Power Module Type 12AB - Page 4
Fig. 1.2 Block diagram of the Type 12AB
1.4 Input/Output
Theinputisa12-pinLEMOsocketonthefrontpanelwhichiswiredup(seeFig.2.3)forthe
G.R.A.S.SoundIntensityProbeType50AIversionsB,CandD.Thisinputisalsoconnectedto
the9-pinD-subconnectorinorderto:
a) Transmitthestate(pressed/notpressed)ofthetwopush-buttonsonthehandleoftheType
50AI
Whenpressed:
thebluebuttontransmitsDSR
thegreybuttontransmitsCTS
b) SignaltheresponsesviathetwoLEDsalsoonthehandleoftheType50AI
Whenlit:
theredLEDissignallingRTS
thewhiteLEDissignallingDTR
Bysuitablyprogrammingthecomputer’ssoftware,measurementsanddataacquisitioncanbe
controlledinteractivelyviathesepush-buttonsandLEDs.
ViatwostandardBNCconnectors(AandB)onthefrontpannel,theprobe’stwooutputsignals
areavailable,DC-decoupledforusewithanalyzers,voltmeters,oscilloscopesetc.
Signal input A
Signal output A
Signal input B
Polarization
voltage
200V
Preamplifier
supply
120V
Preamplifier
supply
28V
0 V
Signal output B
RS 232 lines
AC AC

Intensity Power Module Type 12AB - Page 5
2. External Features
2.1 Front Panel
Thefrontpanelhasthefollowingfeatures(seeFig.2.1)
• Powerswitchandbattery-levelmeter.
Ifthepowersupplyiscorrect,thebattery-levelmeterwillpointtothegreenzone.Ifitpoints
totheredzone,eitherthebatteriesarelowandshouldbechanged(seesection3.1)orthe
externalDCsupplyvoltageistoolow.
• Intensity-probe’sOutputChannels(AOUT B).
BNCsocketsfortheintensityprobe’soutputsignals,takendirectlyfromthePROBE IN
connectorandsucceedinglyDC-decoupled.SeealsoblockdiagraminFig.1.2.
• RS232socket(RS - 232).
9-pinD-subconnectorforfacilitatinginteractiveremotecontrolofintensitymeasurements.
WiringdiagramshowninFig.2.2
• Probeinputsocket(PROBE IN).
12-pinLEMOinputconnectorforthetwomicrophonepreampliersoftheintensityprobe
aswellastheRS232linesforitspushbuttonsandLEDs.Wiringdiagramshownin
Fig. 2.3.
Fig. 2.1 Front panel of the Intensity Power Module Type 12AB
Battery-levelmeter
OputCh.B
Probeinput
12-pinLEMOsocket
Power,On/Offtoggleswitch
OutputCh.A
RS232
9-pinD-subconnector

Intensity Power Module Type 12AB - Page 6
Note:RS - 232andPROBE INareinterconnectedasfollows:
Line    RS - 232 PROBE IN
  DataTerminalReady Pin4   Pin12
  DataSetReady  Pin6   Pin9
  RequestToSend  Pin7   Pin11
  ClearToSend  Pin8   Pin10
Fig. 2.3 12-pin LEMO female socket 1B (external
view). The four inner pins are connected to
the socket shown in Fig. 2.2
Fig. 2.2 9-pin female D-sub connector socket for con-
necting directly to an RS232 computer port
(external view)

Intensity Power Module Type 12AB - Page 7
Fig. 2.4 Rear panel of the Intensity Power Module Type 12AB
2.2 Rear Panel
Therearpanelhasthefollowingfeatures(seeFig.2.4)
• Twist/releaseholderfor315mA(Slow).
• Inputsocketforanexternalpowersupplyof12 - 18 V DC;centrepin+terminal.Theuseof
anexternalpowersupplyautomaticallydisablespowerfromthebatteries.
• Lockingscrew
Unscrewtoremovebaseplateandgainaccesstointernalsettingswitches.
Fuse315mA(Slow)
Inputforexternalpowersupply
12-18VDC
Lockingscrewfor
baseplate

Intensity Power Module Type 12AB - Page 8
3. Internal Features
Note:switchtheType12ABoffanddisconnectitfromanyexternalpowersupplybeforeremov-
ingthebaseplateforanyreason.Afterwardsreplacethebaseplate.
Thebatterypackanduser-servicableswitchesarecontainedwithinthecabinetoftheType
12AB.Togainaccesstothese,rstremovetheknurledlockingscrew(seeFig.2.4)andslide
thebaseplateoff.
Fig. 3.1 Showing the battery pack of the
Intensity Power Module Type
12AB
3.1 Battery Pack
Takeoutthebatterytray(Fig.3.1)andreplaceallthebatteries(10xLR6(AA)standardalkaline
cells),makingsurethatthepolarityisasindicatedonthebatterytray.
3.2 User-servicable Switches
The(internal)user-servicableslideswitchesareshowninFig.3.2.
• Preampliersupplyselectpairofswitches:
- Polarization voltage2-positionswitch(applicabletobothchannels)selects:
0 V  forprepolarized(electret)microphones
or 200 V forexternally-polarizedmicrophones
- Supply voltage2-positionswitch(applicabletobothchannels)selects:
120 V formaximumdynamicrange
or 28 V forminimumpowerconsumption
Fig. 3.2 Showing the internal switches of the
Intensity Power Module Type 12AB
Polarizationvoltage
• 0 V
• 200 V
Supplyvoltage
• 120 V
• 28 V
Note:
SwitchofftheIntensityPower
Modulebeforechangingany
preamplierpowersettings

Intensity Power Module Type 12AB - Page 9
4. Operation
4.1 Batteries and External Power
TheType12ABcanbepoweredeitherbyinternalbatteries(Fig.3.1)orfromanexternalpower
supplyviatheDCinputontherearpanel(Fig.2.4).Ifanexternalpowersupplyisused,thebat-
terieswithintheunitwillbeautomaticallydisconnected.Externalpowershouldbe12-18VDC,
e.g.fromaG.R.A.S.mains/lineadapterAB0002(Europe)/AB0003(USA).
WhenevertheType12ABisswitchedon,thebattery-levelmeteronthefrontpanel(Fig.2.1)
shouldalwayspointtothegreenzonetoensurecorrectoperation.Ifitpointstotheredzone,
eitherthebatteriesarelowandshouldbechanged(seesection3.1)ortheexternalDCsupply
voltageistoolow.
4.2 PolarizationVoltageandPreamplierSupplyVoltage
Polarizationvoltagecanbeswitchedfrom200Vto0V(seesection3.2).Use200Vforstandard
externally-polarizedcondensermicrophones,and0Vforprepolarized(electret)microphones.
Preampliersupplyvoltagecanbeswitchedfrom28Vor120V.Use28Vforminimisingpower
consumption,itisalsosufcientformostapplicationsbutlimitsthedynamicrangeofthemicro-
phonepreampliersusedwiththeType12AB.Use120Vtoutilisethefulldynamicrangeofthe
microphonepreamplier.InthiscasethedynamicrangewillbedeterminedbytheType12AB.

Intensity Power Module Type 12AB - Page 10
5. Service and Repair
Repairsshouldbecarriedoutonlybyqualiedpersonal.TheIntensityPowerModuleType
12ABshouldnotbedismantledwithpoweronbecauseofhigh-voltagecircuits.