We hacked an IKEA LED lamp to turn off automatically after twenty minutes. It’s our version of a light off timer lamp.
We have a bunch of JANSJÖ LED lights in our home.
They’re good quality, they have exactly the right mix of focus, intensity, and bendability. And they’re good value. Great stuff.
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JANSJÖ LED light | IKEA.com
The only snag is that my family tends to fall asleep with the light on.
In the beginning I went around turning the lights off, but now we’ve found a solution that works much better: we’ve converted the lamps into turn-yourself-off-after-twenty-minutes lamps.
Materials for light off timer
If you want to make this lamp, then this is what you will need:
- An LED lamp with a section of low-voltage cord that you can cut; any voltage up to, say, 24 volts will do, but most are between 4 and 12 volts. Our IKEA lamp works perfectly for this. A lamp with a halogen bulb might not work well with this timer, since it draws much more current and doesn’t cut off cleanly; you’d need to do some tests. Do make sure that you’re working with low voltage – don’t try this on a cable that carries mains voltage!
- A logic-level MOSFET, with turn-on voltage below 4 volts; we used the IRF3708 (datasheet) in the TO-220AB package.
- A large electrolytic capacitor (we used 470 muF)
- A large resistor (we used 4.7 MOhm)
- A little piece of stripboard or veroboard (although one can also build the timer without)
- A push-button switch (normally off, push-for-on)
- A container to house the timer
- A voltmeter, or an LED, to to determine the polarity of the cable wires
- Some soldering skills
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This Instructables post contains all the nitty-gritty, but here’s the executive summary.
The cord between the transformer (in the wall socket) and the lamp carries 4 volts, and one can insert a very small electrical circuit in that cord that acts as a timer.
For this you need a few electronic components and some soldering skills.
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The end result is a lamp with an extra button in the cord: if you press the button, then the lamp turns on for about twenty minutes, and turns off at the end.
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Now we can all sleep in peace, knowing all the lights are off.
The post Turn your JANSJÖ into a light off timer lamp! appeared first on IKEA Hackers.
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