Christmas lights tester

Very interesting about the peak power consumpution, as our Xmas is in the middle of summer AND the xmas light thing is starting to catch on, probably due to the cheap chinese lights. So we now have air-conditioners and xmas lights.

bobledoux said:

As a side note, I always wondered how a series wired light string could continue to light when a bulb burns out.

My lights have a wire that holds each end of the filament. Beside one wire is a little metal bar. If the filament burns out the wire springs out making contact with the bar. This creates a short circuit through the bulb. The lost voltage drop in the bulb is shared by the remainder of the light string.

Click to expand...

There is usually a 2 contact shunt across the filament which has a layer of paint (varnish) on the ends. When the lamp works the voltage drop is low (2.5 volts). When the lamp filament burns out the full mains voltage is across the painted junction and breaks through the paint layer and shorts out the faulty lamp.
The lamp which is out is the faulty one. The rest of the string absorbs the increased voltage.

bobledoux
I have seen a test circuit based upon a 4017 IC too, simple but very effective for fault finding in series lights.

Havent had any problems with my led strings yet. these run of 12 or 18 volt transformers.

Super voip
In NZ our summer demand exceeds the winter demand too on certain humid Auckland days.