Instrumentation

Unholtz-Dickie designs and manufactures a variety of transducer signal conditioners, accelerometers, remote charge preamplifiers, vibration monitors & limiters, transducer testers, buffer amplifiers and other special purpose instrumentation accessories for vibration testing.

CVA-4 and CVA-8 Signal Conditioners

(CVA-4) or 8 (CVA-8) Channels
Operates with Piezo Accelerometers, Remote Charge Pre-amps and Self-Amplified Accelerometers
Switchable 10, 100 mV/g (or mV/U) Output for Controllers
Three Pole Low-Pass Filtering
Dial-A-Gain Input Sensitivity Normalization
Buffered Monitor Outputs on Front Panel
Low Cost per Channel
Portable 12VDC Optional (for use with PACS unit)

The Models CVA-4 and CVA-8 are designed to be a low-cost accessory for the APEX SL Windows-based vibration control workstation. They provide either 4 or 8 channels of conditioned acceleration signals for the control or measurement inputs of the Windows-based vibration control workstation or other vibration controllers.

Specifications

General

4 or 8 channels of signal conditioning with separately regulated power supplies for each charge amplifier. Common signal references for all channels.

Inputs

Charge Input: Any single-ended piezoelectric transducer with shunt resistance greater than 10 megohms - Source capacitance of 50 nF causes less than 0.1% gain change - Max. input 13,000 pC (1-10 pC/g); 130,000 pC (10-100 pC/g).
Voltage Input: Coaxial connection to a remote pre-amp/self-amplified accelerometer. Constant current internally adjustable from 2 to 6 mA - 24 VDC compliance voltage.
Charge Calibration: Provides a series 1,000 pF ± 1/2% capacitor for connection to any charge input.
Voltage Calibration: Provides decoupling of the DC current from the external calibration signal source after connection to any voltage input.

Outputs

Rear Panel: BNC output connector ± 10 V pk at 10 mA total current. Switch selection of 10 or 100 mV/g sensitivity.
Front Panel: BNC output connector with same characteristics as rear panel connector - buffered from rear panel connector and short-circuit protected.

Input Sensitivity Normalization

Provided by a range switch (10 or 100 mV-pC/g max) and a precision 10 turn dial for two ranges: 1-10 pc-mV/g and 10-100 pC-mV/g (actually 0.3 to 10.3 and 3 to 103 pC-mV/g).

Noise

.005 pC rms + .0015 pC/1nF source capacitance RTI plus 0.1 mV p-p RTO with 5 kHz LPF.

Front Panel Controls

Input Sensitivity Range (10 max, 100 max)
Input Sensitivity Vernier (0.03 to 1.03 times max value) - 10 turn precision potentiometer and dial
Input Selector (charge or voltage)
Output Sensitivity (10, 100 mV/g)
Buffered Output (isolated BNC)

Rear Panel Controls/Connectors

Charge Input (isolated 10-32 miniature coax)
Voltage Input (isolated BNC)
Output (isolated BNC)
Int-Ext Ground Switch
Line Voltage Selector Switch (115/230V)
Charge and Voltage Calibration Connectors

Physical

Standard Unit Power: 105-125/210-250 VAC; 50/60 Hz, 8 VA (CVA-4), 12 VA (CVA-8)
Portable Option (CVA-4P and CVA-8P): 9-20 VDC supplied with automotive cigarette lighter adapter and wall plug transformer for 120 VAC, 60 Hz. operation.
Standard Unit Dimensions: 17"W x 3.4"H x 13"D with brackets suitable for mounting in a standard 19 inch rack.
Portable Option (CVA-4P and CVA-8P): 17"W x 3.4"H x 7"D with brackets suitable for mounting in a standard 19 inch rack.
Frequency Response: A three-pole Butterworth filter determines the high frequency response. The frequency (fu) is typically chosen to be 3 kHz, but may be customer specified at 1, 2, 5, or 10 kHz.

Model D33 Signal Conditioner

The D33PM Series Signal Conditioner provides virtually all the standard features and many of the optional features of earlier single channel UD signal conditioners in a smaller chassis and at a lower total cost. Independent power supplies are used so that stand-alone operation, as well as multiple channel operation is possible. The power transformers are electro-statically and electro-magnetically shielded so that power frequency components are virtually absent in the output signals. Separable references for the input and output circuits allow an internal differential circuit to remove common mode ground voltages caused by grounding the transducer case at the point of measurement.

.5 Digit LED Meter for Displaying Peak Sine and TRMS
Operates with Piezo Accelerometers, Remote Charge Pre-amps, Single Strain Gages and Self-Amplified Accelerometers
Switchable 10, 100 mV/g (or mV/U) Output for Controllers
Switchable Four Pole Filtering
Dial-A-Gain Input Sensitivity Normalization
High Output Current
Low Cost per Channel

Front panel push-button controls and signal circuitry are contained on two printed circuit cards, which reduces internal wiring greatly and contributes to overall simplicity in layout.

Dial-A-Gain input sensitivity normalization, originated by UD, allows all outputs to be normalized for transducer sensitivities from 0.3 to 100 mV/unit, or pC/unit.

High frequency performance and slew rate performance have been improved to provide accurate high frequency shock measurements. Low frequency performance has also been improved to allow accurate measurements of classical shock tests. The droop in the measurement of the peak value of a 40 ms half-sine shock pulse is typically 5%.

Input signals are accepted by direct connection from piezoelectric accelerometers of force gages, or from accelerometers with internal amplifiers requiring two-wire constant current power source. The adjustable constant current source can also be used for exciting a single strain gage used for AC measurements.

Specifications

General

Enclosed modules with separate power supplies and rear mounted connectors.

Inputs

Charge Input: Any single-ended piezoelectric transducer with shunt resistance as low as 10 kilohms - Source capacitance of 20 nF causes less than 1% gain change - Max. input 13,000 pC (1-10 pC/g); 130,000 pC (10-100 pC/g) at 45 kHz, 100,000 pC at 60 kHz.
Voltage Input: Coaxial connection to a remote pre-amp/self-amplified accelerometer, or strain gage - Constant current internally adjustable from 1 to 20 mA - 25 VDC maximum compliance voltage.
Calibration Input: External oscillator or internal 100 Hz oscillator (option O) - conversion constant 1 pC/mV for charge input calibration.

Outputs

Ranged Output: Calibrated 0 to +/- 10 V pk output at full scale to 100 kHz; output impedance 10 ohms; +/- 35 mA maximum current.
Servo Control Output: Selectable 10mV/g or 100mV/g unaffected by FS range switch; 3 pole Butterworth filtering +/-2% at 5kHz; output impedance 50 ohms maximum.
Meter: 3 1/2 digit LED meter with .5 inch numerals; decimal point automatically positioned; true rms detection; 3 pole averaging; +/- 1 LSD typical jitter at 2 Hz.; switch selectable for peak sine or true rms indication.
DC-Output: 10.0VDC +/- 1% at full scale; response time is 1 s to 90% for step change in input; switch selectable for peak sine or true rms indication.

Input Sensitivity Normalization

Provided by a range switch (10 or 100 mV-pC/g max) and a precision 10 turn dial (actual ranges are 0.3 to 10.3 and 3 to 103 pC-mV/g). For dynamic (AC) strain gage inputs, input sensitivity is (gage factor) x (DC voltage across gage) in mV/1000µL.

Noise

Charge Input: less than .004pC RMS plus .0012 pC/1nF source capacitance RTI plus 2 mV p-p RTO with 10 Hz. HPF and 10 kHz LPF (+/- 2% response).
Strain Gage Input: less than 3µV RTI with a 120 ohm gage and 20mA current.

Front Panel Controls

Input Sensitivity Range: 10 max, 100 max
Input Sensitivity Vernier: 0.03 to 1.03 times max value (10 turn precision potentiometer and dial)
Input Selector: charge in-voltage in
Filter Switches (2): Out-In
Case Switch: Isolated-Grounded
Mode Switch: Operate-Calibrate
Read Bias Switch (momentary)
Adj. Bias: multi-turn potentiometer
Servo (mV/unit): 10-100
F.S Output Dial: 0-10V pk (precision 10-turn)
All push buttons are push-push operation

Physical

Power: 105-125/210-250 VAC; 50/60 Hz
Dimensions: 2.8"W x 5.25"H x 11.5"D with brackets suitable for mounting in a standard 19 inch rack.

Piezoelectric Accelerometers - Models 10B10 and 10B10T

Models 10B10 (left) and 10B10T (right) pictured.

Normalized 10 pC/g charge Sensitivity
Temp. Range -300º F to +500º F
Low Base and Case Strain Sensitivity
Flat Charge Sensitivity vs Frequency
Flat Charge Sensitivity vs Temperature
Mounted Resonant Frequency 30 kHz

The 10B10 and 10B10T Accelerometers are general purpose piezoelectric vibration transducers designed with wide operating temperature range for use in the charge mode. The factory adjusted sensitivity of 10 pC/g is maintained for all units, eliminating the task of matching different transducer sensitivities to companion charge amplifier input settings.

Dyanmic Performance

Charge Sensitivity: 10.0 pC/g ±2%
Open Circuit Voltage Sensitivity: 5.2 mV/g typical
Accelerometer Capacitance: 1,600 pF typical at 100 Hz.
Mounted Resonant Frequency: 30,000 Hz. typical
Transverse Sensitivity: 3% max at 150 Hz. 1% typical
Accelerometer Resistance: 20,000 megohms min at 75º F, 500 megohms min at 500º F
Amplitude Linearity: within 2% of best straight line (2000 g range)

Specifications

Mechanical

Design Type: Compression mode, grounded case, strain isolating double base
Connector: Bismuth Strontium Titanate
Piezoelectric Material
Weight: 1 oz (27 gm) nominal
Mounting: 10-32 internal thread, .145 inch deep
Case: Type 303 stainless steel
Accessories: Various length Microdot low noise cable and 10-32 x 3/8 isolation mounting stud.

Environmental

Dynamic Range: 1000 g sinusoidal, 2000 g shock
Temperature Range: -300º F to +500º F for ±5% charge sensitivity deviation.
Base Strain Sensitivity: 10B10: Equivalent .005g/microinch/inch strain, typ

10B10T: Equivalent .002g/microinch/inch strain, typ
Seal: True hermetic seal, grade A, with welded and glass-to-metal bonds

Calibration of each accelerometer is accomplished by comparison to a NIST traceable reference. Using a UD Model APEX SL-C Digital Calibration Control System, a continuous calibration curve is plotted from 10-10,000 Hz., showing percent deviation of charge sensitivity as compared to the sensitivity measured at the 160 Hz. reference frequency.

Piezoelectric Accelerometers - Model 8B6

Very Stable Sensitivity
Use as Reference Accelerometer
Temp. Range -300º F to +500º F
Low Base and Case Strain Sensitivity
Flat Charge Sensitivity vs Frequency
Flat Charge Sensitivity vs Temperature
Mounted Resonant Frequency 30 kHz
Used as Lab and Working Standard Accelerometer with APEX SL-C Transducer Calibration System

The Model 8B6 Accelerometer features a flat charge vs. frequency response as well as minimum charge sensitivity variation over a wide range of temperatures. The accelerometer design is a single-ended compression type with a double base construction to minimize base strain sensitivity. The Bismuth Strontium Titanate ceramic provides excellent sensitivity stability as well as flat temperature response.

Dynamic Performance

Charge Sensitivity: 8.6 pC/g, ±30% (0.88 pC/m/s2)
Open Circuit Voltage Sensitivity: 2.3 mV/g typical
Accelerometer Capacitance: 1,500 pF typical at 160 Hz.
Mounted Resonant Frequency: 30,000 Hz. typical
Transverse Sensitivity: 3% max at 160 Hz. in any direction, 1% typical
Accelerometer Resistance: 20 megohms min at 75º F, 500 megohms min at 500º F
Frequency Response: 2Hz: 5%, 10Hz: 2%, 160Hz: REF, 1kHz: 2%, 5kHz: 5%, 7kHz: 7%, 10kHz: 15%
Charge Sensitivity: ±5%, 1 to 7,000 Hz.
Voltage Sensitivity (1000 megohm 300pF load): ±5%, 1 to 6,000 Hz.
Amplitude Linearity: within 2% of best straight line (2000 g range)

Specifications

Mechanical

Design Type: Compression, grounded case, top connector
Piezoelectric Ceramic: High Temperature Piezo-Ceramic, Bismuth Titanate (PZ46)
Dimensions: 0.72" hex, .90" height plus connector
Weight: 1.3 oz (36 gm)
Mounting: 10-32 internal thread, .150 inch deep
Case: Type 303 stainless steel
Accessories: 10 ft Microdot low noise cable (3808-10) and 10-32 x 3/8 stud

Environmental

Dynamic Range: 1000 g sinusoidal, 2000 g shock
Temperature Range: ±5%, -300ºF to +500ºF (-185ºC to 260ºC), Curie Temp 650ºC
Base Strain Sensitivity: Equivalent .05g/µinch/inch strain, typical per ISA RP37.2
Seal: True hermetic seal, grade A, with welded and glass-to-metal bonds
Thermal Shock Sensitivity for 10°F Step Input: Equivalent 0.2g/°F, typical with 2 Hz. high pass filter.
Acoustic Sensitivity: 0.1 g rms @ 100 dB broadband, typical
Altitude: Not affected

Calibration of each accelerometer is accomplished by comparison to a NIST traceable reference. Using a UD Model APEX SL-C Digital Calibration Control System, a continuous calibration curve is plotted form 10-10,000 Hz., showing percent deviation of charge sensitivity as compared to the sensitivity measured at the 160 Hz. reference frequency.