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DC Nanovolt Calibrator Model S38

  • DESCRIPTION

    Description

    The EM DC Nanovolt Calibrator model S38 is a precision DC nanovolt source for the calibration of low-level DC measuring instruments.

    The output is taken from across a precision 100 milli-ohm resistor and the output noise is very nearly equal to the thermal noise from this output resistor.

    The noise, thermal drift and output offset are so low that 100 picovolt sensitivity is achievable,and even 10 picovolt sensitivity with care.

    The time constant of the instrument being calibrated needs to be about 10 seconds to limit the thermal noise from the 100 milli-ohm output resistor to about 25 picovolts peak to peak.

    The output terminals are EM special low thermal EMF type manufactured from very pure C101 copper.

    The calibrator output is set by means of 2 decade switches and a calibrated 10 turn potentiometer.

    The accuracy of the S38 is +/- 0.1% of full scale, so 1 microvolt may be set with an uncertainty of 1 nanovolt.

    There is a second, higher level, output from socket at the rear of the instrument, which gives up to plus or minus 1.22 volts, irrespective of range and has the full accuracy specification of the main attenuated output.

    The basic reference for the S38 is taken from two accurate and stable band gap devices, with a typical temperature coefficient of offset of 4ppm per degree C.

    The power supply for the S38 is provided by internal, chargeable batteries. The time before a re-charge is required will depend on the output taken, but is a minimum of 200 hours at 1 millivolt output, rising to over 400 hours with the output set lower.

    The S38 is mounted in an aluminium, screened enclosure, with a plastic outer cover.

  • SPECIFICATION

    Specification: D.C. Nanovolt Calibrator Model S38

    Ranges

    6 Ranges selected by the ‘Multiplier’ switch, giving full scale outputs from 12.2
    nanovolts to 1.22 millivolts.

    Output Resistance

    Attenuated Output. 100 milli-ohms
    High Level Output. 1 ohm

    Accuracy

    Plus or minus 0.1% of full scale, subject to the uncertainty caused by Johnsonnoise from the output resistor.

    Resolution

    Better than 10 ppm of full scale, subject to Johnson noise from the output resistor.

    Temperature Coefficient

    Typically 25 ppm per degree C.

    Offset

    Offset levels of lower than 100 picovolts may be achieved following thermal equilib-ium.

    Terminals

    Special EM low thermal emf output terminals for the main attenuated output.
    4 mm sockets at the rear panel for the high level DVM output.

    Power Supply

    Batteries with internal charger, operating from 50 Hz or 60 Hz, 120 volts or 240 volts.
    Operating time from each charge will depend on the level of output.
    With maximum output voltage, the S8 will operate for about 100 hours and this will extend to over 200 hours at lower output levels.

    Dimensions

    180 mm wide, 90 mm high, 150 mm deep

    Weight

    1.2 Kg