RGB FLASHING LED There are many different flickering and flashing LEDs on the market via eBay. They contain a microscopic microcontroller chip and current limiting resistor. Many of them work on a voltage from 3v to 6v and you can hear the oscillator turning ON and OFF to produce the different effects by building the following circuit:
BIKE FLASHER This circuit will flash a white LED (or 2,3 4 LEDs in parallel) at 2.7Hz, suitable for the rear light on a bike. By Collin Mitchell - 30 LED Project.
1 - 200 Transistor Circuits
#PIRMotionSensor alarm circuit is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. They are most often used in PIR-based motion detectors.