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For compatibility of this card, please consult the Software compatibility and Hardware compatibility tables.

For reference only - Input gain adjustment



Image Removed The information in this regarding the input gain adjustment is for reference only. OPAL-RT no longer recommends modifying the OP5340 gain to acquire high-voltage signals above ±30V.

For higher values, an external module, like the OP8320, must be used.

Calculation of the input gain

To allow adjustment of the gain when the input signal to be measured is above ±20 V, the actual circuitry of each channel includes an additional resistor, Rx, as shown below :

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The Vout formula is then : 

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$$V_{out}= \left( \frac{R2}{R1} \right) \left( \frac{R_x}{R2+R_x} \right) V_{in} $$

which comes to 

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$$V_{out}= \frac{1}{20} \left( \frac{R_x}{25+R_x} \right) V_{in} $$

with the default R1, R2 values of the channel circuit.

With this formula, the user can thus calculate the Rx value corresponding to the input range of the input signals to be measured. Typical values are given in the table below.


Installation of the Rx resistors

To make it easy to adapt the module to the proper gain, a set of 4x2 pins resistor sockets are accessible on the top side of the module. The relation between the resistor numbers and the module channels is given in the table below.

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Users may request the proper resistors for their setup when purchasing the module.