OPERATION MANUAL FOR
1
Series 138
Series 138 Standard Length, with Lead Wire Hole for Attaching Weights
Series 138 Short Length, One-Piece Molded Closed-End Tube
1.0
INTRODUCTION
PCB Series 138 are voltage mode tourmaline sensors
designed for operation underwater or in liquids
compatible with tygon and nylon. (See specification
sheet in the back of the manual for range and
sensitivity).
Series 138 feature built-in ICP
®
amplifiers which
convert the high-impedance voltage from the crystals
into a low-impedance output voltage of less than 100
ohms. Power to operate the IC amplifier and the
output signal is conducted over a single conductor
coaxial cable with a shield serving as signal return.
Special low-noise cables are not required.
Series 138 are used by the military for underwater
explosive testing, commercial use in gasoline tanks
and transformer shock wave applications.
The
sensors are ideal for monitoring dynamic pressures
because they exhibit near non-resonant response.
The charge generated by deflection of the
piezoelectric element when subjected to shock waves
creates a voltage on the input capacitance at the gate
of the amplifier. The amplifier, in conjunction with
the source element, transforms this input into a low-
impedance signal of equal amplitude. The DC bias
that exists on the signal lead is blocked from the
output by a coupling capacitor in the PCB signal
conditioners.
Drawing Number: 21102
Revision: A
Summary of Contents for ICP 138A50
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