What is it?

A compact board packed with an ATTiny microcontroller driving an LM3405 power LED driver. The Tiny is constantly monitoring an on-board motion sensor and can activate the LED driver when motion is detected.

Why did you make it?

I initially designed this to be part of an under-cabinet, motion-sensor-activated LED lighting system...While preparing food in the kitchen, the sensor sees your hands moving and keeps the counter lit up. When finishing in the kitchen, just walk away and the lights turn off a few minutes later. No wasted energy and hands-free operation. We've become addicted to this kitchen light, and I'm sure that this circuit could also be put to many other cool uses.

What makes it special?

Power LED's are a lot of fun to play with but they require some sort of drive/regulation. The LM3405 is a great little chip to control power LED's, and this board gives some great control options in a compact package that can be tucked into a tight area. Instructions are available (soon to be a kit with all specialized parts as well) to build this into an under-cabinet, motion sensor activated power LED strip.

What's Included:

• LED controller board with all components tested. Default LED current is regulated to 700mA
• Fresnel Lense for PIR sensor
• A tactile switch with a 9mm stem...This is shipped unsoldered as it's a very tall part and I'm concerned of it becoming damaged in transit. Also, you have the option to use a different switch if you don't need the height.

Specifications:

• Input Voltage: 5-15VDC. A minimum 5V is required to keep everybody running, with a few components having a max rating of 15V.

• The number of LED's that you can drive depends on the input voltage, current settings and the voltage drop of the LED's at that given current. By default these boards are configured to maintain a constant 700mA output. It's important to remember the maximum input voltage is 15V. Assuming an LED that drops ~3V at 700mA, the maximum number that could be placed in series is 4, totaling 12V. Running 5 would require more than the maximum 13.5V output of the LM3405.

Use this to run any power LED's with compatible current needs. Optional Lumileds LED's with adhesive reflectors are available here in Neutral or Cool. Note that these LED's generate a lot of heat and so they require some sort of heat-sinking Running these power LED's without a heat sink will cause the PCB to get extremely hot, causing a fire risk and may lead to premature LED failure.