[kip51035]

When I run my engines usually just inside the garage door under the florescent light. If I do not turn it off the readings are really screwy.

[cravenjw]

Exactly, two signals, lights and prop.

[HAL9KPCM]

Originally Posted by moo

Incandescent light works better, Fluorescent lights don't turn off all the way and new ones (and compact fluorescent) are much faster than 60Hz.

Electricity is 60Hz, a light bulb doesn't change that. What can happen with a CFL is that due to the spiral construction, your tach is actually picking up the very small fraction of a second between one part of the coil and a second part.

[cravenjw]

Originally Posted by HAL9KPCM

Electricity is 60Hz, a light bulb doesn't change that. What can happen with a CFL is that due to the spiral construction, your tach is actually picking up the very small fraction of a second between one part of the coil and a second part.

Sorry, cfl ballast circuits do rectify the 60hz AC, then have high freq inverters, that output to the tube. This one of the features that make them more efficient.

[HAL9KPCM]

Ah yes... this is the more recent trend, so in that sense, you are right. I've still got some older ones that are still running a 60Hz even on the output side, they're old, and I can make a tach work properly, but you pretty much have to get right up to one section of the bulb.