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Summary of Contents for GRAS 12AB
- Page 1 Instruction Manual 12AB 2-Channel Power Module for GRAS Intensity Probes...
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Page 2: Table Of Contents
CONTENTS Introduction and Description ........3 Polarization Voltage . -
Page 3: Introduction And Description
A block diagram of its main components is shown in Fig. 1.2. 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 Preamplifier Voltage Supplies The preamplifier 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 Power Supplies The Type 12AB can run on internal batteries with a battery life of approximately 10 hours using G.R.A.S. preamplifiers, 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). Fig. 1.1 Intensity Power Module Type 12AB * Factory settings for use with GRAS Sound Intensity Probe type 50AI version B Intensity Power Module Type 12AB - Page 3... -
Page 4: Input/Output
Preamplifier Polarization supply supply voltage 120V 200V Fig. 1.2 Block diagram of the Type 12AB 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: 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 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. Intensity Power Module Type 12AB - Page 4... -
Page 5: External Features
• 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 preamplifiers of the intensity probe as well as the RS 232 lines for its push buttons and LEDs. Wiring diagram shown in Fig. 2.3. Power, On/Off toggle switch Battery-level meter Output Ch. A Oput Ch. B RS 232 9-pin D-sub connector Probe input 12-pin LEMO socket Fig. 2.1 Front panel of the Intensity Power Module Type 12AB Intensity Power Module Type 12AB - Page 5... - Page 6 The four inner pins are connected to the socket shown in Fig. 2.2 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 Intensity Power Module Type 12AB - Page 6...
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Page 7: Rear Panel
Fuse 315 mA (Slow) Input for external power supply 12 - 18 V DC Locking screw for baseplate Fig. 2.4 Rear panel of the Intensity Power Module Type 12AB 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. Intensity Power Module Type 12AB - Page 7... -
Page 8: Internal Features
Supply voltage • 120 V • 28 V Polarization voltage Note: • 0 V Switch off the Intensity Power Module before changing any • 200 V preamplifier power settings Fig. 3.2 Showing the internal switches of the Intensity Power Module Type 12AB Intensity Power Module Type 12AB - Page 8... -
Page 9: Operation
Operation 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 Preamplifier 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. Preamplifier supply voltage can be switched from 28 V or 120 V. Use 28 V for minimising power consumption, it is also sufficient for most applications but limits the dynamic range of the micro- phone preamplifiers used with the Type 12AB. Use 120 V to utilise the full dynamic range of the microphone preamplifier. In this case the dynamic range will be determined by the Type 12AB. Intensity Power Module Type 12AB - Page 9... -
Page 10: Service And Repair
Service and Repair Repairs should be carried out only by qualified personal. The Intensity Power Module Type 12AB should not be dismantled with power on because of high-voltage circuits. Intensity Power Module Type 12AB - Page 10... -
Page 11: Specifications
Operating temperature range: -10 °C to +50 °C Dimensions: of a standard 19-inch rack) Height: 132.6 mm (5¼ in) Width: 34.6 mm (1.3 in) Depth: 196.0 mm (7.7 in) Weight: 770 gm (1.69 lbs) Accessories available: Manufactured to conform with: Intensity Probe: Type 50AI (versions B, C and D) CE marking directive: 93/68/EEC Mains/line adapter: WEEE directive: Europe: AB0002 2002/96/EC USA: AB0003 19-inch Rack-mounting System: AK0040 RoHS directive: 2002/95/EC Intensity Power Module Type 12AB - Page 11...
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