Airmar T1 User manual

Applications
•For use with Airmar’s line of AT ultrasonic
transducers.
•To aid in designing ultrasonic systems.
•Allows the designer to quickly and easily transmit
and receive echoes.
Features
• Jumper selectable frequency and pulse width for
optimal interfacing.
•Transmit pulse is amplified to 400Vpp via a power
MOSFET and transformer.
•Received echoes can be viewed at X1, X10, X100,
and X1000 amplification.
Operation
1. Connect J4 to a 12V power supply capable of at
least 125mA.
2. Connect the transducer to J5.
3. Aim the transducer directly at a flat reflecting
surface.
4. Connect a scope to one of the four echo
amplification positions on J3.
5. Insert jumpers J1 and J2 at the position
corresponding to the AT model being evaluated.
This sets the initial values for frequency, pulse
width, and pulse rate.
6. Using P2, tune the operating frequency for the
maximum echo.
7. Using P1, adjust the pulse width to give the
desired echo width.
17-143 rev. 2 3/98
AIRMAR
®
OPERATING INSTRUCTIONS
T1 Development Kit
IMPORTANT : Please read the instructions completely before proceeding.
Figure 1. T1 development board
transducer (+)
transducer (-)
echo X1
echo X10
echo X100
echo X1000
ground
+12V
P2, frequency
P1, pulse
width adjust
J1, jumper
J5
J3
J2, jumper
J4
adjust

Ta b le 1: Jumper position and adjustability
Model J1 and J2
Position Range Pulse Rate
Pulse
Width Frequency
AT-25 1 80cm-30m 3Hz 120-2400µs 25-34kHz
AT-41 2 30cm-20m 5Hz 80-1600µs 35-46kHz
AT-50 3 25cm-15m 6Hz 60-1200µs 43-56kHz
AT-120 4 15cm-7m 10Hz 40-800µs 100-130kHz
AT-200 5 10cm-3m 25Hz 16-320µs 180-220kHz
AT-225 6 8cm-2.5m 25Hz 16-320µs 200-260kHz
Custom 7 — — — —
Custom 8 — — — —
1000
0
200
400
600
800
300050 100 150 200 250
Figure 2. Capacitance vs. operating frequency
Operating Frequency ( in kHz )
Capacitance (
in pF
)
Jumper Position and Adjustability
The currently available AT models with their
corresponding pulse width and frequency adjustability
using the T1 development board are shown on Table 1.
(These values are approximate.)
Custom Application
Rows 7 and 8 on the table above are left open for the
designer. On the T1 development board, insert the new
capacitors at C7 and C15 and/or C8 and C16.
Calculate the capacitance value for C7 and/or C8 to
produce a new minimum pulse width as follows:
C = PW/175, where C is in µF and PW is in µsec.
The maximum pulse width will be approximately 20
times the minimum pulse width. To find the
capacitance value for C15 and/or C16 which will
produce a new operating frequency, refer to Figure 2.
Alternatively, an external pulsed signal (such as one
generated by a microprocessor) may be amplified and
applied to a transducer using the T1 development
board. In this case, disconnect the circuit at R9
(bypassing the signal generation portion of the T1
development board) and connect the external signal to
Q2 and Q3.
AIRMAR
TECHNOLOGY CORPORATION
35 Meadowbrook Drive, Milford, New Hampshire 03055-4613, USA
Phone [phone]
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Fax [phone]