flickering LEDs

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flickering LEDs

Postby argent » Sun Jun 09, 2019 8:59 pm

At my nephew's wedding last week I noticed that on the tables amongst glass pebbles and delicate hand crafted flowers were little flickering battery operated tea light candles. I asked my wife "do you know what they are?" to which she replied, "freesias" "no, not the flowers, those" I pointed to the tea light."Oh thats probably scenery" she said. Do you think she's heard me say that a time or two before?

After most of the guests had gone and the very happy couple had gone to do better things, I asked my sister what she was going to do with all the little tea lights. she said that she hadn't thought that far ahead but they would most probably go into the recycling bin. "You can't do that Gill" I said "there's batteries in them that must be disposed of properly, let me do it for you, see how cunning I am? so I went aruond to pocket all the little tea lights, Got a dozen or so but a lot were already missing. I wondered if there was another modeller with a keen eye in the room and filled my wife's hand bag with my booty.

The next morning I took one apart. not only is there the yellow flickering LED but also of coure was a coin cell battery and with a bit of delicate soldering, a switch. the ideas were coming to me all the way through my sunday lunch, fire place fire, bonfire, brazier, using the lot I could simulate a forest fire and if that might be a bit ambitious at least a heath fire.

Any other suggestions?

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Re: flickering LEDs

Postby End2end » Sun Jun 09, 2019 10:10 pm

I bought some flickering tea lights from poundland thinking they were elaborate enough to include a flasher circuit and switch inside.
No luck. All the plastic slide switch did was to push over the 2nd LED's leg to touch the other side of the battery making the connection.
I concluded that it's the actual LED that flickers, not some internal circuit.
No problem!. Solder another LED of a colour of your choosing (blue for example) to the original flashing LED and paint the original over in black so you cannot see it.
Now what was a flashing warm white is now a flashing blue light. The original LED will flash the 2nd LED. :idea:

A word of warning. I always regulate (and suggest to do so) LED's with a 1KOhm resisitor to stop them blowing.
In this scenario you'd only need 1 resistor and the circuit would be as follows...
Power + to 1KOhm Resistor
1KOhm resistor to Positive led of the Flashing LED.
Flashing LED Negative to 2nd LED Positve
2nd LED Negative to Power -
Hope it helps
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Re: flickering LEDs

Postby Bufferstop » Sun Jun 09, 2019 11:13 pm

Most LEDs can be persuaded to flicker if you get the voltage just right, it seems to be quite critical on some so I suppose the ones in the tea lights have a wider voltage range over which they flicker. We have quite a pile accumulated after Christmas and various parties. They've usually got them in Poundland, they can be quite a cheap way of buying the coin cells, the lights being cheaper than the cells that go in them.
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Re: flickering LEDs

Postby Bigmet » Mon Jun 10, 2019 8:29 am

The wedding 'event' organisations have tons of this good stuff, judging by the last few I have been to. Picked up handfuls of 'strings' of miniature LEDs with an intent for coach lighting last year, had the resistor in the battery pack of 3xAA. It was all going in the bin! Do I believe the hotel would have treated the 'waste' properly? This is railway modelling as a public service.

Another good one, LED arrays in 240V lights. My wife's uncle had an LED exterior bulkhead light malfunction. (Installing electrician had cracked the board by taking the twin and earth into the lamp body, then forced under the board with the LED's on it to access the terminals. All he had to do was invert the housing to give direct access to the terminals, or mount it long axis horizontal, there were four knockouts to choose from. Crossed his name off uncle's contractor list.) Anyhoo, loads of LED's for me! I found an identical housing bulkhead lamp at a fraction the price with a proper bulb in it.

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Re: flickering LEDs

Postby Buelligan » Mon Jun 10, 2019 9:45 am

I've got about 50 of those battery tea lights, bought them last year for a Christmas project that I didn't really get time to do.

I'm sure you've probably all already heard of the company, but if you want just the led to wire up in series to various places, component shop sell flickering LED's for between 30p and 17p, depending how many you buy, https://www.componentshop.co.uk/5-mm-le ... -lens.html

I think they do other colours too.

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Re: flickering LEDs

Postby Jim S-W » Mon Jun 10, 2019 10:22 am

Used some years ago wired in series with a streetlight to give that on the day failed effect (dayburner)

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