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Tuesday, 3 June 2008

Electronic Candle (Warning: Geeky!)

Many years ago when I was so high and much nicer I saw a circuit for an electronic candle in a magazine. There's quite a lot available ready-made these days but this design needed a match to light it!

The light from the match fell on a photocell and the resultant current triggered a thyristor that latched in the on state completing the circuit from battery to bulb. So I made one housed in a toilet roll centre with woodworking glue dripped down the side to look like wax.

Quite cool but I wasn't satisfied. A real candle would have the "blowing out" function so I added a slip of aluminium foil that shorted out the thyristor with the wind in the right direction. This was really good because when you blew the candle out, it momentarily shone brighter - just like old-fashioned wax and wick technology. I did wonder about adding a smoke generator. Not difficult - I already knew that if you broke the glass on a bulb and gave it power there was a lot of smoke but it only lasted about 5 seconds.

When I showed the "candle" to my friends and family, I made an interesting discovery. If you apply a lighted match to something that isn't a real candle or a cigarette, a lot of people get rattled and dive for cover. Very odd!

Links:
Apprentice Geek Ruth talks about BCD clocks
An electronic candle that is said to flicker realistically
About Thyristors

2 comments:

Sweet Camden Lass said...

That's just terrible cool. ~x~

PurpleSparkleBright said...

I feel rather behind.