Anyone using two Otii for Negative Power Supply?


Hello everyone,

Has anyone tried using two Otii in configuration for Negative power supply?

Two Otii with the same project configuration,
let’s say 3.0V and in standard scheme like this:

[Otii1]  [Otii2]
 [+ -]     [+ -]
 + (-       +) - 
 + (   GND   ) -

I have already filed a support ticket, if there is something internal, which might disrupt such wiring or maybe the measurements. But I then thought that maybe someone has already tried this. Or is maybe even using it?



Hi Dimi,

This setup is possible, but you need to add an USB isolator for Otii2.
Otii Arc black banana plug is internally connected to USB GND so if you do not isolate the USB connector for Otii2 there will be a short circuit.
You also must not use an external DC power with GND connection on Otii2 due to the same reason as above.

Best regards,


Hi Bjorn,

Thank you for this information!

What would be a proper USB isolator for this case or could you directly recommend one?

I am thinking about something similar to



Hi Dimi,

I don’t have much experience of USB isolators so no recommendation from me.
What you should look for is low drop in VBUS voltage and that the isolator can handle enough power.

Best regards,