Let's Make Robots!

Xmas Lights Tester

So, you accidentally stick a regular clear bulb in your Christmas lights (fairy lights [US] ?) instead of a fuse bulb. Next time there's a bit of a surge, there's no discernable weak point in your circuit and it takes out more than one bulb. Where do you start debugging that?

Sure, you could sit with a multimeter and probe all the bulbs to find the duff ones. Have you ever tried to attach multimeter probes to a fairy light bulb?!?! It's a nightmare. Specially when you only have 8 fingers and two thumbs.

My bulbs have these little skimpy connectors and I think they're enamelled, so you'd be really lucky to get a closed circuit even with a good bulb.


Knickers to that. Chop one of the bulb holders out of the set and attach it onto a pair of 4mm banana plugs. Test all 40 bulbs in about 2 minutes. Patch the bulbholder back in. As it happens, 11 of them were blown (not bad!) and I only had 5 spares. So the whole set went into file #13 (the garbage).


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What are fairy lights?

I was trying to disambiguate for my American cousins across the pond. The strings of Christmas lights which come out once a year for those who celebrate Christmas.

No one in America says Fairy Lights unless maybe "their door swings the other way".
I keep trying to think of another use to put a string of Christmas lights to, or the wire. Ready made sockets, and I believe the bulbs pull out of the bases if the wires are straightened. Possibly insert LEDs, and run a group string on a different voltage?

Me too. Trouble is that to be under MCU control it would probably need to be low voltage. These bulbs can run 140mA at 2.5V if you have a 100 light set. If 10 of them are on at the same time, that's 1.4 amps. That's gonna need a heck of a sized PSU.

I have a couple of LED chains running of a 2x AA cells. They weren't terribly expensive, either.

Fairy lights? Christmas Lights? Oh, you mean Solstice lights...
Are you one of those non-religionists? (That's for a different thread, me thinks.)

I hadn't thought of that! I have a strand I've been dreading to test, now I feel a bit better :P

Nice new icon btw :) 

Sure, you could sit with a multimeter and delving all the bulbs to acquisition the duff ones. Accept you anytime approved to attach multimeter probes to a bogie ablaze bulb?!?! It's a nightmare. Specially if you alone accept 8 fingers and two thumbs.

Which is why I soldered a bulb holder to my multimeter.