Twinkle Twinkle little star

[Jimk]

What's the prize? updated Photoshop?

[John]

I can understand slowly twinkling Xmas lights and the ones that gently undulate. But why Flashing ones??

[Chris J Dixon]

Quite!

Another design gotcha, which resulted in my returning a B&Q set some years ago, is to have no retained memory of the mode chosen, so that if on a timer, it is impossible to arrange matters so that it stays static next time it is switched on. :-(

Chris

[ARW]

To keep the chavs happy or course:-)

[mm0fmf]

#firstworldproblems

[Steve Walker]

I am glad to say that the three sets of lights outside do retain their mode - not that it matters too much outside. Unfortunately the lights on the Christmas tree don't :(

SteveW

[Brian Gaff (Sofa 2)]

Maybe hey get a thrill out of it, oh sorry my AI got the wrong end of the branch there. If you will recall back in the days of filament bulbs all wired in series across the mains, we had a flashing bulb in the chain. This device had a bi metal strip which crudely cut of and connected the lights to make them flash. Of course the danger here was that if a bulb blew short circuit then you could get a wonderful catastrophic failure resulting in a blown fuse and a set of lights with no good bulbs at all. I'm sure we all remember those halcyon days of trying to find the duff bulb or bulbs before you ended up blowing them again. What I used to do is buy two sets and put them in series, that way they were a bit dimmer, but actually the redder light looked more festive, but of course, flashing bulbs no longer worked. Brian

[Brian Gaff (Sofa 2)]

Have you heard some of the RFI generated by Christmas lights these days? From gently gurgling to whining noises. I suppose they all have dirt cheap switch mode supplies with a convenient aerial to radiate the crap built in.

Brian

[Dave Liquorice]

Not a lot different now, have chains of LEDS across a supply of a few tens of volts.

Tree light bulbs are designed to fail short circuit. I've never known a set run away blowing bulbs or the fuse bulb. Failing short makes finding the duff one fairly easy, it's the one that isn't lit. Fail open and you have to test each bulb individually.

[The Natural Philosopher]

All the lights I had failed open

[Roger Hayter]

The ones i remember all but one of the bulbs had internal wire resistors in parallel with the filaments so that they failed at about twice the reslstance of a normal bulb. This had little effect on brightness until quite a few bulbs had failed. But one the bulbs was a designated fuse bulb which failed open circuit as the filament (a thicker one?) carried the whole current. These were usually painted white rather than coloured and were not as bright when lit as the others.

[The Natural Philosopher]

Nope. All the bulbs were simply fail open, Bought a 9V bulb tester to plug em all in before plugging em into the tree. Thank Clapton for LEDS...

[Halmyre]

We've got a couple of sets of these but IIRC the other bulbs could still fail and it was a bugger tracing the faulty one.

I do remember one time going to Homebase to try and find some spare bulbs, optimistic fool that I am, didn't get any of course but they were already selling off the Christmas decorations at a massive discount so I got two boxes of 100 lights for five quid.

[Brian Gaff (Sofa 2)]

Well the danger was that the fuse bulb blew and people put in an ordinary bulb, that was how you got runaway failure. In my experience the magic number was around 6, at that point the next one to blow vaporised internally, saving the rest! However the rest were then weakened and for the rest of the Christmas you were eternally replacing bulbs. Brian

[Brian Gaff (Sofa 2)]

The les 24 volt ones usually did, these were big bulbs, not the weedy push in crap we got later on. How having single insulated twisted wire live to full mains in crap little plastic sockets was ever safe in the first place eluded me. My series ploy at least made them pretty fail safe until the cat tried to pull them off the tree, that is. Brian

[Chris J Dixon]

Indeed! A couple of sets that I had even came complete with a bulb tester. What a pain to get them all working each year.

If it wasn't failed bulbs, it was poor contact in the primitive wedge bulb holders.

Chris

[Brian Gaff (Sofa 2)]

High tech, I never found any resistors in my old bulbs or holders.

Brian

[Ian Jackson]

In message <qta1ap$u6s$ [e-mail]>, "Brian Gaff (Sofa 2)" [e-mail]> writes

'Twas ever thus. It was around 1950 that we got our first 12-bulb set of Christmas lights. I think they were originally 'always on', but you could buy a flasher bulb that contained bi-metal make-break contacts. The regular wideband RF splat as the lights innocently turned on and off carried a considerable distance, and when listening to the radio (no TV in those days) the flasher bulb had to be temporarily replaced with a normal type. [I still have the set, but about half of the bulbs are blown. The only way to run them now is to put some silver paper in the dead bulb sockets, screw in the dead bulbs, and run the remainers from a reduced voltage.]

[John]

I think you are now supposed to buy a couple of new sets every Xmas.

[ARW]

Rewire them to parallel and use a 12V power supply.