LM317T Voltage Regulator with Pass Transistor

This is a video of an LED Lamp Modulator circuit. The purpose of the circuit is to flash an LED lamp such as is used as a brake light or even a turn-signal on a motorcycle in an eye-catching way to increase the conspicuity of the motorcycle. The circuitry is very simple: A 7805 5V linear voltage regulator, a PICAXE 08M microcontroller, a TIP31 NPN BJT power transistor to drive the LED lamp, and a few resistors and one capacitor. All the "work" is done by the program in the microcontroller. This video shows modulation pattern v1. The pattern can be changed by editing the control program using the PICAXE program editor. The 'v1' program occupies about 62 bytes out of the 08M's 256 bytes total memory. Theoretically, I could fit anywhere from 1 to 4 modulation patterns and use a switch or jumper wires to allow the user to select the desired modulation pattern. The circuit is easily modified to operate off of the license-plate lamp circuit. This would allow it to light the LED lamp at 20% or 30% brightness when the brake is not being applied (the behavior of automotive brake lamps) and still flash when the brake is applied.



http://www.youtube.com/watch?v=axghYIyuCVo&hl=en