On Sat, 31 Mar 2007 18:53:13 +1000, "Phil Allison"
wrote:


"Fred Bartoli"

** Another brain teaser.

The scope trace shows the actual, continuous AC current draw of a
common household item operated on 240 volts/50Hz.

Current peaks = +/- 4.4 amps.

RMS value = 0.24 amps.

PF = 0.23

CF = 18.3


You gave the answer in the pic name :-)


** You were not supposed to see that !!

Now, can you say what the problem with this is ?


CFL HF input cap + triac delayed firing optimized for highest peak current
(at top of sinusoid).



** The control on the commercially made, domestic lamp dimmer is set to max.

With incandescent lamps it traverses the whole, half cycle range just fine.

At lower settings, the current draw becomes half wave with much larger
peaks.

Now, can you say what the problem with this is ?

---
EMI/RFI?


--
JF