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DC Isolator Model I71

  • DESCRIPTION

    Description

    This new magnetically coupled electronic isolator is designed to be used with internally integrated EM DC Nanovolt Amplifiers, models A22, A23 and A39.

    One problem with very low level DC measurements is that they are prone to interference from noisy power supplies and also from the device that they are coupled into.

    The power supply problem can be overcome by using batteries and this reduces the problem of interference from noisy power supplies, but this still leaves the problem of noise from the device which follows the amplifier. This is a more difficult problem to overcome and nearly always requires a very high gain to be used in the input amplifier.

    One other very important advantage of having an isolated supply and also isolating the output of the DC preamplifier is that the amplifier can be used in differential mode. This is very important for many measurement applications, and allows the amplifier to measure small signals with a high degree of common mode voltage present.

    These isolators may be used with internally mounted EM Nanovolt Amplifiers, models A22, A23 and A39 and this makes measurements much easier without the recurrent problem of interference limiting the level of possible resolution.

    The I71 is magnetically coupled and provides a high degree of isolation, making ultra-low level DC measurements much easier.

    The I71 provides for a linear isolated reproduction of the DC output of the A22, A23, A39 amplifier modules.

    The power necessary to operate the amplifier modules is provided with the same degree of isolation achieved for the signal.

    The isolated signal noise specification is better than 1 microvolt peak to peak at the output, which, if a gain of 10000 is used for the Nanovolt Amplifier, will add just 100pV, referred to the input of the amplifier.

    The isolation resistance is greater than 100GΩ with a typical unbalanced capacitance of 1 pF, thus rendering the I71 along with its Nanovolt Amplifier ideal for many measurement applications.

    The accuracy of the DC signal is also very good, being better than 0.5%, with a linearity specification of 0.1%.

    There are 2 outputs, the first is a direct output which gives a rise time constant of 100 milliseconds and there is also an active filter output which has a rise time constant of 1 second.

    The input power supply required is plus or minus 8 volts to 12 volts at 10 milliamps.

    The I71 is housed in a very high isolation resistance enclosure, ensuring that the common mode resistance is extremely high connection, making low level isolated DC measurements convenient and easy.

  • SPECIFICATION

    Specification: DC Isolator Model I71

    Input Level

    This depends on the DC Nanovolt Amplifier used.

    A22: Plus or Minus 20mV DC

    A23: Plus or Minus 2mV DC

    A39: Plus or Minus 20mV DC

    Gain

    This is set at the input by connecting appropriate components to the feedback terminals.

    Accuracy
    Isolated Output, Direct. +/- 0.5%

    Isolated Output Filtered +/- 0.5%

    Linearity
    Output better than 0.1%

    Zero Drift
    This is determined by the specification of the internal amplifier.

    Noise
    This is determined by the specification of the internal amplifier.

    Input Impedance
    This is determined by the specification of the internal amplifier.

    Input Offset Voltage

    This is determined by the specification of the internal amplifier.

    Input Voltage Offset Temperature Coefficient

    This is determined by the specification of the internal amplifier.

    Offset Current
    This is determined by the specification of the internal amplifier.

    Response Time Constant

    Isolated Direct Output: 100 milliseconds

    Isolated Filtered Output: 1 second

    This is also affected by the feedback components used and any filtering of the isolated amplifier will be added to the overall specification.

    Outputs
    Direct output with a rise time constant of 100 milli-seconds.

    4 pole active filtered output with a rise time constant of 1 second.

    Isolation
    Resistance: Common Mode > 1TΩ.
    Common Mode Voltage: 100V Peak Max

    Common Mode Rejection Ratio
    Greater than 160dB DC

    Connectors
    Isolated Connections.

    Inputs. 3mm solder tags for signal input.

    Outputs: 3mm solder tags for plus and minus output power and isolated 0v.

    Non Isolated Connections:

    Power Input: 3mm solder tags for plus and minus supply voltage and 0v.

    Signal Outputs: 3mm solder tags for direct and filtered outputs.

    Power Supply Requirement
    Plus and Minus 8 volts to 10 volts. 10 milliamps

    Dimensions
    Length: 135mm (5.3″)
    Width: 82.5mm (3.25″)
    Height: 53mm (2.1″) Including terminals.

    Weight
    115g (4oz)