The first rear light i made was based on the very first front white LED bike light i made in late 2009. The red rear light was made within a few weeks of the front one it was based on. I used a 4 x white LED MR11 lamp as this was the first affordable LED lamp i came across. This LED lamp has a stated output/consumption of 0.6 Watt. The law regarding bicycle lighting states that no white light must be shown to the rear. To achieve a red light a piece of red plastic film was placed over the lense of the white LED lamp and the white side looking LED's were replaced by red ones. The construction of the rear lamp body was identical to the front one.
This picture shows the front components of the rear bike light. As the LED lamp has no lense cover one was made from a piece of stiff plastic salvaged from an empty washing up bottle! Also shown is the red lense filter used to convert the light from use at the front to the rear. This is easily removed. It was originally a sweet wrapper!
The black rubber seal belongs to the original plumbing part and serves two functions here, keep out water and help hold the LED lamp in place.
The silver foam is water pipe insulation which had a conical shape carved into the front to mount the LED lamp.
This picture shows the front of the light with the red filter fitted.
The body of the light has 'side looking' LED's which help the cyclist to be visible at junctions.
The 'side looking' LED's are mounted in LED holders to securely hold them in place. See below for further details.
The on/off switch is mounted at the rear and a rubber water proof cover is included.
This picture shows the rear light temporarily mounted on a piece of wood on the rear of the bike!
This temporary mounting technique allowed quick testing of the light without having to wait until a more permanent method was found to mount it on the bike.
It was impressive to see the distance that the light could be seen from when mounted on the bike. It easily matched incandescent bulbs of the same wattage.