Today I bought an LED bulb from a local shop that starts with T and ends in O it's one of there own brand according to its packaging it should consume 9 watts and give the same light as a real 60 watt bulb. Anyhow I took it to my shack a to test how much RFI it made I was pleasantly surprised that it only seemed to give a little rectifier noise on the higher bands name 15 and 10 meters. The noise disappeared completely when I connected my digital multimeter on AC volts between the metal lamp base and earth just to see how much leakage voltage was on the metal base it was around 11 volts one way and around 8 volts the other way polarity reversed by swapping the supply wires. Next I thought ide try the lamp on DC not expecting it to work but surprise surprise it worked fine fed with around 230 VDC from a full wave rectifier it worked fine pulling around 27 mA adding a capacitor for a bit of smoothing gave 330 VDC and the lamp remained lit for a couple of seconds while the cap ran down. Final test was running it on AC of 240 volts it took 70mA from the mains I will re check the figures tomorrow as I don't get why there would be the difference in current. Finally after running the lamp for around 40 minutes the plastic base of the lamp was too hot to touch other than that it seemed fine
On AC you'll have power factor to contend with - from those numbers it sounds like it'll be worse than 0.5 - with DC there's no such thing as power factor so the current draw should be 'flat' as it were.
There again your AC current meter is probably making all kinds of assumptions when converting the instantaneous currents its sensing (which will vary from millisecond to millisecond as the AC waveform moves along) to a single value to display - probably assuming that the current is a pure sine wave - while in practice it's likely to be anything but.
On AC you'll have power factor to contend with - from those numbers it sounds like it'll be worse than 0.5 - with DC there's no such thing as power factor so the current draw should be 'flat' as it were.
There again your AC current meter is probably making all kinds of assumptions when converting the instantaneous currents its sensing (which will vary from millisecond to millisecond as the AC waveform moves along) to a single value to display - probably assuming that the current is a pure sine wave - while in practice it's likely to be anything but.
