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How do watch glow backlights work??? Answered

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????


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...

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.

And, I guess, glow nightlights work the same way, only fed directly from the AC. Niiiice!


9 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