Category Archives: Gadgets

Submergible 12V swimming pool lights


In the wintertime the evenings get dark and therefore plunging in to the dark lake is not as pleasant as it is in the summer. Led lights to the rescue!

Above is a photo of the lights in a pool, or actually a hole in the ice in a lake.

Submergible led lights can be made with a car battery, a couple of 1 watt leds, a constant current driver, a piece of clear 1 inch diameter PVC hose and two small pieces of e.g. aluminum profile for led heatsinks. The leds Continue reading Submergible 12V swimming pool lights

Sound triggered glowing led eyes for Halloween


As we are getting close to Halloween, I’ll present this project I did last year. It is about  a pair of leds that will light up when there is a loud sound, such as a person raising her voice. The intensity of the leds will depend on the loudness. I used yellow leds as the eyes for a moose/elk antler trophy at my cottage. For this project, as for many others, I used a Picaxe 08M2 microcontroller. Picaxes are inexpensive, very simple to use, BASIC language programmable and Microchip Pic based, see You can do surprisingly much with them.

The project has two parts, a small board for the Picaxe and another for a sound sensor with condenser microphone, amplifier and peak detector. Continue reading Sound triggered glowing led eyes for Halloween

Motion activated joule thief led bike light

Joule thief based bike led light installed on a bicycle.

I have been wanting to make something useful with the joule thief circuit design and some 1W star leds that I have. I found an old bicycle light that used a 0.5A 2.5V halogen bulb and two C size (LR14) batteries. It looked like it would be a good candidate to convert to led. I also wanted to create a light that would switch on automatically as the bike moves, and off again with a delay after the bike stops moving. In other words a motion sensor activated light that I would not need to switch on or off. That would Continue reading Motion activated joule thief led bike light