Unlike major brands, FNIRSI usually distributes firmware via direct Google Drive links, WeTransfer, or Telegram channels found in their YouTube video descriptions.

Method A: The Official YouTube Channel This is the most reliable source.

Method B: Rebrand Sources (DDS140) Since the DSOTC2 is a clone of the Miniware DDS140, you can sometimes use Miniware firmware, but this is risky.

Method C: Community Archives The EEVblog forum has a massive thread dedicated to these oscilloscopes.

The firmware implements a simplified version of the open-source “Transistortester” by Karl-Heinz Kübbeler [2]. Key differences:

Reverse engineering revealed a known bug: capacitor ESR (equivalent series resistance) measurement is erroneously scaled by ×10 for values > 10 µF, likely due to a missing divider correction.