Set new hour meter

dwp wrote: I have also read articles saying that the true hours are found on the older hour meters, as the new digital hours are not true due to increasing/decreasing RPM's from the engine (not sure about that, have not researched it).

You are correct, their are two types of hour meters, once that only measure the time when the engine is "on." These are typically called "Hobbs Meters" hobbs being a genericized name for a meter originally designed and manufactured by the Hobbs Meter Company. I think eventually they were purchased by Honeywell.

The other type of hour meter measures Tach Time. These "hour" meters actually count the number of Revolutions the engine turns (RPM). They are typically configured to reflect the same time on a Hobbs meter at a pre-determined RPM - usually what would considered a normal "cruise" RPM. When running at that power setting, the Tach Time meter and Hobbs meter will record "time" at the same rate. Tach Time has become more the standard because it runs slower at lower (then the optimum) RPM's and faster at higher RPM's.

So if you are trying to "Fake out" your gauge, you should be able to get the tach time to run faster if you increase the frequency of your generated wave form. A "square wave" would most likely work best because it gives you longer time for the gauge to recognize the peak and the trough.

Wow - apparently I actually did pay attention in my engineering school classes a hundred years ago...