EM Electronics.

 

DC ISOLATOR MODEL I71

 

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 100 G ohms 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 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 > 1 Tohm.

 

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)

 

 

 

About EM Electronics

Selecting the Correct Nanovolt Amplifier

 

Low Level Voltage Measuring Instruments

 

Ultra Low Level DC Voltage Amplifiers
 

Low Level DC Voltage Amplifier Modules

PC Boards for Modules 

 

Contact EM Electronics
 

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