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
If the lamp is only intended for 220 volt to 250 volt circuits, then it should operate down to about 190 volts. That allows for a nominal 220 volt supply that is at the lower limit of 90%, or 198 volts actual, and a few volts lost in the consumers installation.
If the lamp is intended for USA or European supplies, then it should operate down to about 100 volts, or a nominal 120 volt supply at the lower limit of 90%, or 108 volts actual, and again allowing for drop to below 108 volts within the premises wiring.
If for true worldwide use, then it should work down to about 85 volts, to allow for Japanese 100 volt circuits.
BTW, ELV LED lamps are also available with a wide operating voltage range. I have some intended for 10 volts to 30 volts, DC. Suitable for nominal 12 volt systems with a low battery and some voltage drop in the wiring, or for 24 volt systems with the battery on boost charge. Or indeed for nominal 16 volt systems if any such remain in use.
If the lamp is only intended for 220 volt to 250 volt circuits, then it should operate down to about 190 volts. That allows for a nominal 220 volt supply that is at the lower limit of 90%, or 198 volts actual, and a few volts lost in the consumers installation.
If the lamp is intended for USA or European supplies, then it should operate down to about 100 volts, or a nominal 120 volt supply at the lower limit of 90%, or 108 volts actual, and again allowing for drop to below 108 volts within the premises wiring.
If for true worldwide use, then it should work down to about 85 volts, to allow for Japanese 100 volt circuits.
BTW, ELV LED lamps are also available with a wide operating voltage range. I have some intended for 10 volts to 30 volts, DC. Suitable for nominal 12 volt systems with a low battery and some voltage drop in the wiring, or for 24 volt systems with the battery on boost charge. Or indeed for nominal 16 volt systems if any such remain in use.
