Standalone probe mode (similar to Offline continuity test)

Similar to the offline continuity test in another post, it would be handy to be able to have a mode similar to continuity but for voltage in circuits similar to 24vdc industrial circuits it.

I would envision this implemented using a low voltage threshold setpoint in the app. When voltage on the test leads are above that voltage, the continuity beep would sound and the indicator on the probe would light. 

This would be really helpful for quick control circuit logic checks.