Motion sensitive RGB lamp can standby for 3 years

Ooooh, nice enclosure! This is a little motion sensing lamp which [Krazatchu] built a few years back as a Mother’s Day gift. The PIR sensor is easy enough to see as the white dome on the front of the case. But look closely below that and you’ll see the LDR which it uses to keep the thing asleep during the day. This is intended to save on batteries but the original version still ate through them like crazy. This year he gutted it and worked out a much more power-friendly design.

He moved to a TLC1079 OpAmp which greatly reduced power consumption when reading from the PIR sensor. The microcontroller was also upgraded from an ATtiny13 to an ATmega328, making the new version Arduino compatible. It puts itself to sleep and keeps the lights out during the day, drawing just 0.08 mA. When driving the RGB LED the lamp pulls about 50 mA. That should still last a while on three AA batteries but we’d still recommend using rechargeables.

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Alarm clock wakes you like [Lawrence Welk]

That awful buzzing/beeping beside the bed in the morning might not seem so bad if it were a cascade of bubbles instead. At least that’s what [Will] is hoping for. He took a child’s toy and turned it into a bubble blowing alarm clock.

We’re guessing you’re not going to be too happy with the alarm settings feature. This isn’t using a real-time clock, or any clock at all really. [Will] rolled his own light detection circuit using a PNP transistor whose base is controlled by an LDR. When the light level in the room reaches a certain threshold the bubbles start streaming out of the front of this thing. He test the system in the video by switching a lamp on and off in a dark room.

Up at dawn has never been a way we could describe ourselves, but the one-wire control method seen here could easily be provided by a microcontroller rather than the LDR. Oh, and for those that don’t get it; the [Lawrence Welk] show always started with a screen full of bubbles.

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Light programming for a clock


So at first glance we were thinking there wasn’t much special about this clock. It’s based on an Arduino and displays the time using a character LCD screen. But then we realized that there’s no battery-backed RTC and no buttons. How the heck do you set the time on this thing? [Mossblaser] is using a light programmer to set the time using a computer screen.

We’ve tried nearly the same data transfer technique before, using a white and black flashing computer screen to push Manchester encoding to a light dependent resistor. We were met with limited success, but you can see that [Mossblaser’s] rig is much more reliable and we think there’s a few reasons behind this. First, he’s only sending five bits per seconds, a very slow speed when it comes to digital transmissions. This helps to make up for slow LCD screen refresh. Also, the LDR is surrounded by material on the back of the case that will help to block out ambient light. And finally, he’s using a smaller part of the screen instead of flashing the whole thing. This may result in more accurate timing. You’ve got to admit, this is pretty slick!

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Sun-powered Stirling engine with automatic tracking

Check out this solar-powered Stirling engine (translated). The build is part of a high school class and they packed in some really nice features. The first is the parabolic mirror which focuses the sun’s rays on the chamber of the engine. The heat is what makes it go, and the video after the breaks shows it doing just that.

But the concept behind the mirror makes for an interesting challenge. The light energy is focused at a narrow point. When the sun moves in the sky that point will no longer be at an efficient position to power the engine. This issue is solved by a pair of stepper motors which can reposition the dish. It’s done automatically by an Arduino Uno which makes readings from four LDR (photoresistors) in that cardboard tube mounted at the top of the dish. If the light intensity is the same for all four, then the tube is pointed at the sun. If not, the motors are tweaked to get the best angle possible.

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Automatic flashlight tag damage sensor

You’re out at night and playing a boisterous game of flashlight tag. But how can you tell if you’ve been mortally wounded by your opponents light beam? [Kenyer] solved this problem by building a flashlight tag damage sensor which is worn by each participant. It adds a bit of the high-tech equipment used with laser tag while keeping a low-tech price tag.

The sensor relies on a light dependent resistor to register hits when a flashlight beam passes through the round window. It will only register one hit in a three-second time period. At the end of the game, the total number of hits recorded can be flashed back using an on-board LED to see who is the victor. You can see a demo of this functionality in the clip after the break.

[Kenyer] started with a breadboard prototype using an Arduino as the driver. Obviously the cost of an Arduino for every player is a bit ridiculous. He scaled down the project, running the Arduino code on an ATtiny microcontroller. Continue reading “Automatic flashlight tag damage sensor”

Light sensitive MIDI glove

The latest offering in glove-based noisemakers forsakes commonly used flex sensors in favor or photoresistors. [Bruno Ratnieks] is responsible for this musical glove and his methods will be very easy to recreate. He used an Arduino to interface with it while providing a USB connection to your audio software. The sensors themselves couldn’t be easier to throw together, with each photoresistor creating a voltage divider when combined with a fixed-value resistor. That’s all the hardware you need, and with some creative coding you can making it do much more than the effects heard in the video after the break.

Some will say that [Bruno] simply didn’t used enough duct tape with his project design. Be we liked how he wove the wiring into the mesh of these knit gloves to keep it firmly in place.

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