🚀 go-pugleaf

Iskandar Taib (ntaib@silver.ucs.indiana.edu) wrote:
: In article <727805456snz@harrier.demon.co.uk> bob@harrier.demon.co.uk writes:
: >
: >>Actually, regarding calibrating to an electric light wouldn't that be
: >>1800 rpm for a two blade prop or 1200 for a three blader?
: >>
: >>Also, you would need a fluorescent light or some other light that
: >>flickers more than an incandescent light.
: >>
: >>Just a thought...
: >
: >>Wrrooonnngggggggg... An incandescant lamp running on 50 Hz mains actually
: >flashes 100 times/sec. The sine-wave goes both posative and negative peaks
: >in ecah cycle, ie 100 flashes/sec. Multilpy by 60, gives 6000 flashes per
: >minute.. So on the two blade setting it should read 300 ( 3000rpm ) and on 
: >three blade 200...
: >
: >I guess your side of the pond where you run at 60Hz it would read 360 and 240.
: >
: >I'm not an expert on flourescant lights, (or much else really) :-) but they
: >run via some really high voltage gizmo which makes the gas in the tube 
: >flouresce constantly....
: 
: Hmmm
: 
: I think this is backwards. The filament of an incandescent lamp 
: doesn't have enough time to cool down enough between cycles, so
: it should glow steadily. A fluorescent lamp, however, relies on
: the flow of electrons through a mercury vapor through the tube,
: and this can respond faster to the cycles of AC. 
: 
: Whether they flash 60x per second or 120x per second I don't know.

Ok... I've got one and I've tried it.  In TFM the calibration mode is
claimed to work on incandescent lights.  But it works on both types equally
well.  The way I figure, it is a pretty sensitive bugger.  But then
I suppose it has to be to "see" the prop without any backlighting or
anything.

Steve Jahr
jahr@hprnd.rose.hp.com