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Low-cost 3 1/2 Digit Strain / Microvoltmeter

Low-cost 3 1/2 Digit Strain / Microvoltmeter
Programmable preamplifier
Isolated 10-24 Vdc bridge excitation supply
Independent bridge-balance, zero & span adjustments
±1,999 count display span
120 dB CMR, 70 dB NMR
Bright, 14.2 mm (0.56 in) LED display
Automatic zero and polarity
Display hold and test
115/230 Vac power
EMI/RFI filter for AC power
Screw-terminal barrier strip
Short (4.1 in, 104 mm deep) 1/8 DIN case

Isolated 9-32 Vdc power
Isolated 26-56 Vdc power
NEMA-4 splash-proof lens cover

1 Year Warranty

Scroll Below to Order Specs Manuals Mechanical Mechanical

Model 202A-S is a low-cost 3 1/2 digit panel meter in a short 4.1 in (104 mm deep) 1/8 DIN case for applications that require bridge excitation and resolution down to 10 microvolts. Zero, span and bridge-balance adjustments are accessible behind the lens, so that the 202A-S can read out directly in engineering units for a wide range of bridge inputs or other low-level signals.

Model 202A-S is primarily intended as a digital indicator for pressure cells and metal-foil load cells. It can also be used as a low-level, high-impedance process meter with zero and span adjustments, or as a DC voltmeter with resolution down to 10 microvolts, required by 50 mV current shunts.

Resolution and Accuracy
Resolution is 1 part in ±1,999 counts, or 0.05% of full scale. Accuracy is 99.9%. A ratiometric reference input eliminates AC line and load regulation errors and reduces overall meter span tempco to 0.01% of reading/°C.

Bridge Excitation Supply
The built-in excitation supply of the 202A-S is transformer-isolated to 500 Vac from the rest of the meter. A multiturn potentiometer accessible behind the lens allows adjustment of the output voltage from 10 to 24 Vdc. Maximum output current is 30 mA.

Mircovolt Preamplifier
The preamplifier of the 202A-S provides an input impedance in excess of 1 G to ensure that the signal source is not overloaded. Gains of 1, 10 and 100 are selectable by solder bridges and provide resolutions of 1000, 100, and 10 µV/count, respectively. Typical offset drift is only 0.3 µV/°C.

Mechanical options are a PCB edge connector for handshake signals and a splash-proof lens cover which meets NEMA-4 requirements. Power options are isolated 9-32 Vdc and 26-56 Vdc.
Load Cells

available from NEWPORT®
Analog Input
Most-Sensitive Scaling
Least-Sensitive Scaling
±19.99 mV
2.5 V (limited by CMV)
10 µV/count
1 mV/count
Preamplifier Gain
Gain Attenuator
Configuration: Differential, ratiometric
Polarity: Bipolar
Input resistance: 1 G
Bias current: 1 nA typ, 5.5 nA max
Maximum voltage: 50 V
Coarse preamplifier gains: 1, 10, 100
Gain attenuator: Adjustable from 0.001 to 1
Bridge-balance range: ±50% of bridge span
Zero-adjustment range: -1,000 to +1,000 counts
Span-adjustment range: 0 to 2,000 counts

NMR, SIG HI to SIG LO: 70 dB, 50/60 Hz
CMR, SIG GND to SIG HI: 120 dB at gain 100, DC to 60 Hz
CMV, SIG GND to SIG HI or LO: +2.5 Vdc
CMR, SIG GND to PWR GND: 120 dB, DC to 60 Hz
CMV, SIG GND to PWR GND: 1500 Vp test, 354 Vp per IEC spacing

Error, max: ±0.05% of reading ±1 count
Balance tempco: ±0.3 µV/°C typ, ±1.0 µV/°C max
Zero tempco: ±0.01% of zero/°C
Span tempco, ratiometric: ±0.03% of reading/°C
Span tempco, non-ratiometric: ±0.3 µV/°C
Full-scale step response: 1.0 s
Warmup to rated accuracy: 10 min

Technique: Dual-slope, average-value
Signal integration period: 100 ms
Read rate: 2.5/s

Output voltage: Adjustable 10 to 24 Vdc
Output current: 30 mA at 10 Vdc decreasing to 12 mA at 24 Vdc
Line regulation: ±0.01%/V of AC power
Load regulation: ±0.5%
Ripple at 50/60 Hz: ±0.01%
Tempco: ±0.02%/°C
Reference signal: 1.0 V typ at 10 V output (Eliminates line and load regulation errors and reduces overall meter span tempco to ±0.01%/°C)
Display Type: 7-segment, red LED
Display Height: 0.56 in (14.2 mm)
Symbols: -
Decimal points: Three positions, programmable by jumpers behind lens or at connector, 10 mA sink
Overrange indication: Three least-significant digits blanked

Level: TTL or 5 V CMOS compatible

AC voltages: 115 or 230 Vac ±15%
AC frequency: 49-440 Hz
DC voltages: 9-32 Vdc, isolated to 300 Vp; 26-56 Vdc, isolated to 300 Vp
Power consumption: 3.7 W max
Output Voltages: +4.7 Vdc and -4.7 Vdc ±5%, 10 mA max

Operating temperature: 0 to 60°C
Storage temperature: -40 to +85°C
Relative humidity: 95% at 40°C (non-condensing)

Dimensions: Newport DIN2A (1/8 DIN) case (see Mechanical section for drawings)
Weight: 15 oz (425 g)
Case material: 94V-0 UL-rated polycarbonate
Connector for signal and power: D4 screw-terminal barrier strip (standard)
Connector for control lines: D1 36-pin PCB edge connector (optional)

Product Selection (Specify Model Number, see variations below in partnumber builder table)
 Part Number   Availability   Price    Description   
 Strain Indicators, default calibration: 0 - 100 mV = 00.0-100.0 and 10-24 V excitation set to 10 Vdc
 202A-S in-stock    $315.00     3 1/2 digit (±1,999 count) digital indicator for strain gages and bridge transducers (SB1)  
 302-S     Consult sales   With INFINITY® style bezel and adapter  
 Process Receiver, default calibration: calibration: 4-20 mA = 00.0-100.0
 202A-P in-stock    $213.00     3 1/2 digit (±1,999 count) process receiver  
 302-P     Consult sales   With INFINITY® style bezel and adapter  
 Process Receiver with excitation output, default calibration: 4-20 mA = 00.0-100.0 and 10-24 V excitation set to 24 Vdc
 202A-E in-stock    $280.00     3 1/2 digit (±1,999 count) process receiver with excitation output (EB1)  
 302-E     Consult sales   With INFINITY® style bezel and adapter  
 Factory Setup
 ,FS     Consult sales   Factory Setup and Configuration, $45 Charge  
All dollar amounts on this site are shown in US currency.

 Part Number Builder
(1) (2) (3) (4) (5) (6)
Option Descriptions
(1) Model
202A for standard model
302 for model with INFINITY® Style Bezel and Adapter
(2) Input Configurations
-S for Strain/Microvolt Meter with Excitation Output
-P for Process Receiver
-E for Process Receiver with Excitation Output
Nothing(leave field blank) for 115 Vac, 50/60 Hz
,C1 for 230 Vac, 50/60 Hz
,C3C for Isolated 9-32 Vdc
,C3E for Isolated 26-56 Vdc
Nothing(leave field blank) for Red LED display
,G for Green LEDs for display
Nothing(leave field blank) for No Options
,BL for Lens without Newport logo
Nothing(leave field blank) for No Options
,FS for Custom calibration for models 202A-S / 302-S. Specify in millivolts for min/max input, and min/max display, and excitation of 10-24 Vdc. Specify decimal point position for display. $45
 NOTE: All combinations may not be valid, check spec sheet for valid part numbers.

Keywords: Low-cost 3 1/2 Digit Strain / Microvoltmeter

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