Originally Posted by
Hacker15e
"AC lies, DC dies" is the phrase you're looking for.
This works for analog gauges, but not necessarily for other functions. AC powered gauges tend to stop in position or invert with power loss, while DC powered gauges tend to simply go back to zero (or in some cases indicate last position); the "lies" function of AC primarily points to AC anaolog gauges occasional propensity to invert or indicate out of phase or incorrectly.