I've got a little problem. I've got a house with a lit address number. All the homes in the subdivision have the same device. Doggone thing is wired up 27 volts A/C and is wired for two incandescent bulbs in series. Bulbs don't last long. The homeowners association insists everyone keep these displays operational.
I'd like to put some LED's in there. It doesn't have to be crazy bright, the sign has to be simply illuminated. My goal is to have something with low power draw, and long life.
Any recommendations on how to proceed?
–Do I just add a rectifier, then place a few strands of LED's in series with appropriate resistance to create safe current flow and account for all voltage drops?
–What happens to a LED diode in an A/C circuit?… does it just 'flash' 60 times per second at 'half' illumination intensity or is that a really bad idea?
–Or am I better off finding a decent low power AC to DC converter chip and move along from there?
Best Answer
Why not just add a diode (rated at the right current) and leave the lights as they are - they'll be dimmer and quite possibly last longer (possibly not true for halogen). The idea of the diode is that the bulbs will be delivered with 50% of the power they had previously because the diode will block 50% of the power.
If it doesn't improve the lamps life then proceed with the LEDs - you'll need to choose LEDs that match the bulbs intensity (or half the intensity) and choose the appropriate current limiting device. The current limiting device may also need to be a switch mode regulator to prevent overheating and failure of that.