Project:SpeedAdjustableBikeLight
LED lights and lenses for my bike
I plan to have several strings of LEDs with different beam angles and aiming points - and the appropriate string of LEDs turned on for the current bike speed.
Plan
Project journal is now in dropbox/bikelight/project-bikelight.nb
Project overview and status is here.
Overview
My motivation is to have fun while learning about designing PCBs, and using microcontrollers, MOSFETs and LEDs - with a simple objective to measure my progress against.
I came across this page that explains the benefits of matching LEDs to bike generators.
Since LEDs seem cheap and the available energy is small, I refined the plan. Build several strings of LEDs with different beam angles and aiming points - and the choose the string of LEDs to turn on for the current bike speed and conditions.
Initial target:
- generate some diffuse light at low speed
- generate more focused light at high speed
- make it work
- dont break the bank
Advanced target:
- during the day, flash the LEDs to attract attention.
In progress lessons
- how to use Eagle CAD:
- to make components
- to enter schematic
- to layout a board
Physical progress
Have components, circuit boards, solder paste.
Todo
- Software
- Solder stencil
- Surface mount soldering
- Through hole soldering
- Testing
Open questions
- How to mount and cool the LEDs?
- on a horizontal copper heat pipe
- How to mount the circuit board?
Electronics
Plan is now for
- four LED strings (*)
- - very low speed - just a 120 deg med power LED
- - low speed - one 30deg
- - med speed - one 30deg, one 15deg
- - high speed - one 15deg, two 5deg
- LED voltage sense for fine control
- light sensor - to allow different night and day policies
- JTAG debugging
- possible communications via SPI, TWI, ...
(*) the length of the strings depend on the Voltage generated, and will be changed to match.
This easily fits in the attiny84 - with space for JTAG also.
New link on impedance matching and MCU control of bike lights :). I am not sure what this means for my circuit. My plan is to continue on:).
