Auto-calibration after removing noisy offset on output?

[hmartinsson]

Hi,

I am considering removing 2 resistors per channel on my STEMlab 125-14 v1.0 to reduce the noise in the output channels, see https://ln1985blog.wordpress.com/2016/0 ... rformance/

But before doing that I'd like to know if the DAC calibration and the auto frequency calibration will work, or if I need to use a tweeked version of the manual calibration procedure.

The alternative is to add the voltage regulators, see https://ln1985blog.wordpress.com/2016/0 ... put-stage/. But I'd prefer 0/+2 V rather than -1/+1 V output for my application.

Best regards,
Hans

[redpitaya]

Hello hmartinsson,

Thank you for writing on the forum.

We do not advise altering the board because users have reported problems after doing so. Every board made has undergone rigorous testing, which cannot be claimed for modified boards. Any non-Red Pitaya hardware modification will void the warranty, and we cannot guarantee support for modified boards.

Otherwise, this modification should not affect the calibration application (this is as long as the output range does not change). If the changes affect the output voltage range, then you will have to make modifications to the calibration application (at least the automated DC calibration). The Manual DC calibration should not be affected.

As a side note, the modifications found on the two links are part of the improvements made on the STEMlab 125-14 Low-Noise version of the board.

[hmartinsson]

Thanks for a quick reply!

Yes, I am aware that any warranty will be void if I modify the board

Thanks for confirming that at least the manual DC calibration will work. Disconnecting the offset voltage on the output will not change the range (still 2 V, although 0-2 V instead of -1 - +1 V) but the offset will (from 0 V to +1 V).

Yes, any new Red Pitaya will be the low-noise version. What other improvements have been made on the low-noise version?

/Hans

[redpitaya]

The basic changes between STEMlab 125-14 and STEMlab 125-14 Low-Noise are summarised here:
https://redpitaya.readthedocs.io/en/lat ... -125-14-ln