Info on Voltage Limiter Operation
Frankly, I never paid much attention to the "dope" on the old units. "Back then" they usually work or they didn't. After all, you can't adjust them, LOL
But about the figuring. We don't have a sine wave here, I'm not sure RMS applies, but "my math" has been awhile. Why would it not be a simple percentage off 12-14V, that is 5V/ 14 or 40 something percent?