On Thu, 19 Mar 2009 20:07:16 +1100, "Phil Allison"
wrote:


"mick"
Phil Allison wrote:

** Two pics of scope screens for SED

Same 23 watt CFL used in each case for current trace.

Normal AC supply versus pure sine wave supply.

Voltage trace = 100 V per div

Current trace =120 mA per div



How did you get the clean AC, Phil? I'm assuming that the blip on the
voltage waveform where the CFL fires is because the supply isn't of a low
enough impedance, so is it from the output of an amplifier, stepped up
through a step-up transformer?


** Yep.

I used a 600 watt mosfet amp driving a 300VA toroidal in reverse, fed from
my bench sine generator set to 50 Hz.


Your mains supply looks rubbish!


** Fraid the same wave shape is almost universal.

Ever checked your local AC power voltage wave shape ?


Are you on the end of a long feed?


** In the heart of Sydney's inner suburbs.



...... Phil


Same bulb, but I'd bet that your "pure sine wave" drive actually
consumes more power.