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 sensors 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 features 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 is 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: B
Summary of Contents for ICP W138A02
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