Atec Endevco-25B User Manual

ENDEVCO

MODEL
25B

ISOTRON®Accelerometer

Model 25B

• Low Impedance Output

• World's Smallest ISOTRON

®

• Detachable Coaxial Cable

• Light Weight (0.2 gm)

• Ground Isolated

DESCRIPTION

The ENDEVCO®Model 25B ISOMIN™is an
extremely small, adhesive mounted piezoelectric accel­erometer with integral electronics, designed specifically
for measuring vibration on very small objects. The
unit weighs only 0.2 gm, reducing unwanted mass
loading effects. The "B" version of Model 25 offers a
flexible, detachable coaxial cable which can be replaced
by the user in the field. This feature provides extended
service life when repetitive installations or heavy use
are expected. As with the "A" version, Model 25B is
ideal for measuring vibration in scaled models, small
electronic components, and biomedical research. An
optional triaxial mounting block (Model 2950M16) is
available for setting up three-axis measurement.

The Model 25B features ENDEVCO’s PIEZITE®Type
sensing element operating in shear mode. The internal
electronics inside the accelerometer convert high
impedance input into low impedance voltage output
through the same cable that supplies the required 4 mA
constant current power. Signal ground is isolated from
the mounting surface of the unit by a hard anodized
surface. A removal tool is included for proper removal
in the field. A 4,000 g’s full scale range is available in
the 25BM1 version.

ENDEVCO Signal Conditioner Models 133, 4416B,
2792B, 2793, 2775A (set to 4 mA ± 0.5 mA), are
recommended for use with this accelerometer.

Actual size

Optional triaxial
mounting block

MODEL 3006-120 CABLE

(REMOVABLE - SUPPLIED

ATTACHED TO ACCELEROMETER)

10-32 COAXIAL PLUG

.036 DIA COAXIAL CABLE

STANDARD TOLERANCE
INCHES (MILLIMETERS)
.XX = +/- .03 (.X = +/- .8)
.XXX = +/- .010 (.XX = +/- .25)

.065

(1.65)

SERIAL NUMBER

R FULL

UNIT IDENTIFICATION

.225
(5.72)

.108

(2.74)

.150

(3.81)

TYPICAL AMPLITUDE RESPONSE

% DEVIATION

1 10 100 1000 10000 100000

FREQUENCY IN HERTZ

APPLIES TO CALIFORNIA FACILITY

20

15

10

5

0

-5

% DEVIATION

-10

-15

-20

-60 20 100 180 260

(-51) (-7) (38) (82) (127)

TYPICAL TEMPERATURE RESPONSE

TEMPERATUREoF (oC)

20

15

10

5

0

-5

-10

-15

-20

ACCESSORIES

Model 3006-120 (10 ft) CABLE ASSEMBLY [4]
P/N 31836 REMOVALTOOL

OPTIONAL ACCESSORIES

Model 2950M16 TRIAXIAL MOUNTING BLOCK
P/N 31849 ADHESIVE MOUNTING KIT
P/N EJ21 10-32 TO BNC ADAPTOR

NOTES

1. Excessive current supply may cause permanent damage to
accelerometer.

2. Short duration shock pulses, such as those generated by
metal-to-metal impacts, may excite transducer resonance and
cause linearity errors. Send for TP290 for more details.

3. Adhesives such as petro-wax, hot-melt glue, and cyanoacry­late epoxy (super glue) may be used to mount the accelerom­eter temporarily to the test structure. An adhesive mounting
kit (P/N 31849) is available as an option from Endevco. To
remove an epoxy-mounted accelerometer, first soften the
epoxy with an appropriate solvent and then twist the unit off
with the supplied removal wrench. Damage to sensors

ENDEVCO

MODEL
25B

ISOTRON®Accelerometer

SPECIFICATIONS

The following performance specifications conform to ISA-RP-37.2 (1964) and are typical values, referenced at +75°F (+24°C), 4 mA, and
100 Hz, unless otherwise noted. Calibration data, traceable to National Institute of Standards and Technology (NIST), is supplied.

DYNAMIC CHARACTERISTICS Units

RANGE g ±1000
VOLTAGE SENSITIVITY

Typical mV/g 5

Minimum mV/g 4
FREQUENCY RESPONSE See Typical Amplitude Response
RESONANCE FREQUENCY kHz 50
AMPLITUDE RESPONSE [2]

±5% Hz 2 to 8000

±1dB Hz 1 to 12 000
TEMPERATURE RESPONSE See Typical Curve
TRANSVERSE SENSITIVITY % ≤ 5
AMPLITUDE LINEARITY % < 2 to F. S.

OUTPUT CHARACTERISTICS

OUTPUT POLARITY Acceleration directed into the base of the unit

produces positive output
DC OUTPUT BIAS VOLTAGE Vdc +8.5 to +11.5
OUTPUT IMPEDANCE Ω ≤ 600
FULL SCALE OUTPUT VOLTAGE V ±5.0
RESIDUAL NOISE equiv. g rms ≤ 0.007
GROUNDING Signal ground isolated from mounting surface.

POWER REQUIREMENT

SUPPLYCURRENT [1] mA +3.5 to +4.5
VOLTAGE Vdc +18 to +24
WARM-UP TIME sec < 3

ENVIRONMENTAL CHARACTERISTICS

TEMPERATURE RANGE -67°F to +257°F (-55°C to +125°C)
HUMIDITY Epoxy sealed, non-hermetic
SINUSOIDAL VIBRATION LIMIT g pk 500
SHOCK LIMIT g pk 2000
BASE STRAIN SENSITIVITY equiv. g pk/µ strain 0.002
ELECTROMAGNETIC SENSITIVITY equiv. g rms/gauss 0.09

PHYSICAL CHARACTERISTICS

DIMENSIONS See Outline Drawing
WEIGHT gm (oz) 0.2 (.01)
CASE MATERIAL Aluminum Alloy, Hard Anodized
MOUNTING [3] Adhesive

CALIBRATION

SUPPLIED:
SENSITIVITY mV/g
TRANSVERSE SENSITIVITY %
FREQUENCY RESPONSE % 20 Hz to 12 kHz

caused by inappropriate removal procedures are not covered
by Endevco’s warranty.

4. Follow the Instruction Manual carefully when replacing the
cable assembly in the field.

5. Maintain high levels of precision and accuracy using
Endevco's factory calibration services. Call Endevco’s inside
sales force at 800-982-6732 for recommended intervals, pric­ing and turn-around time for these services as well as for quo­tations on our standard products.

Continued product improvement necessitates that Endevco reserve the right to modify these specifications without notice. Endevco maintains a program of con­stant surveillance over all products to ensure a high level of reliability. This program includes attention to reliability factors during product design, the support of
stringent Quality Control requirements, and compulsory corrective action procedures. These measures, together with conservative specifications have made the
name Endevco synonymous with reliability.

ENDEVCO CORPORATION, 30700 RANCHO VIEJO ROAD, SAN JUAN CAPISTRANO, CA92675 USA [phone] [phone] fax [phone]
www.endevco.com Email:[e-mail]

0201

ISOTRON

(each channel)

Constant

Biased
Output

Current
Source

+ Voltage Supply

Decoupling

Capacitor Unbiased

Output