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How do watch glow backlights work???

I recently took apart a digital watch that had a green glow type of backlight. Looks like there was a backplate, behind the LCD screen, with what seems two contacts on opposite ends. No matter how I hook up these contacts to a 1.5V battery, I can't get it to glow. Any ideas????

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caitlinsdad8 years ago
tinkernaut (author)  caitlinsdad8 years ago
Thanks, thanks, thanks! Please tell Caitlin she has a fantastic Dad! Looks like they use an RC oscillator and a transformer... in a watch?!?! Now if only had a circuit...
PKM tinkernaut8 years ago
RC oscillators are one thing the DIY/maker community do well. Specifically the joule thief might be of interest to you, it's a small and simple DC voltage multiplier which I'm sure could be adapted to provide the voltage necessary as long as it's not too crazily high.

The charge circuit from a camera flash unit might work if you need higher voltage but comes with an attached health warning.
tinkernaut (author)  tinkernaut8 years ago
And, I guess, glow nightlights work the same way, only fed directly from the AC. Niiiice!
westfw8 years ago
There are special purpose integrated circuits that will drive these sorts of "Electroluminescent panels." Usually they are designed to use a physically small inductor. Search for "EL driver"
Here's a representative page from SuperTex
westfw westfw8 years ago
You can also use the inverters designed for "glow wire"/etc to drive the panels, although they'll typically be a bit over-powered.