Background : Rectangular Rear Light
I developed this rear light about 4 years ago to be mounted on the rear carrier of my bike. I used the 12, 0.6W, 4 x LED bulb i had originally used to develop my first front light. In addition i added two groups of 10mm diameter high brightness rear facing LED's together with two groups of high brightness side facing LED's to improve visibility at junctions and in traffic.
The light is constructed in a red translucent box which has slotted internal walls making it ideal for mounting PCB's. The box is mounted on the rear carrier of my bike.
The entire unit is powered from 12V and consumes a total of 120mA.
The light is constructed in a red translucent box which has slotted internal walls making it ideal for mounting PCB's. The box is mounted on the rear carrier of my bike.
The entire unit is powered from 12V and consumes a total of 120mA.
The light consists of 3 main sub-assemblies:
- 12V/0.6W 4 a LED bulb(MR11) centrally mounted in the box.
- 2 x PCB's containing rear facing and side facing 10mm high brightness LED's.
- Switch and interconnecting wiring loom.
A piece of terminal block and wiring connects the components together and to the 12V supply.
The rear facing and side facing LED's are mounted on a PCB that is held in place by the inbuilt slots of the box.
The LED's are 10mm high brightness RED units connected with 5 in series across the 12V supply with one current limiting resistor in series with the LED's
The three LED's are arranged as follows, three rear facing and 2 side facing.
To improve the light output and ensure as much of the light as possible left the box in the correct direction pieces of silvered plastic foil were placed around the PCB's directing the light out of the box.
Holes were drilled in the rear panel of the box to allow it to be mounted on the light bracket of the rear carrier of my bike.
This shows the rear light being bench tested while connected to a 12V supply, actually a PC Power Supply converted to a bench top power supply. Click here for further details.