Saturday, August 24, 2013

LED Lighting: Preparing the Housings

While waiting for the brake and shifter cable housings to arrive, I'm going to start preparing the light housings for conversion to LEDs.  The Sturmey Archer Dynohub and lights were an option on the 1953 Raleigh Sports Tourist.  This particular bike has the smaller front light housing, I believe the larger housings were used only on the Superbe models.  I previously converted the lights on my 1949 Comrade Roadster to LED's; however, it used larger housings.  Hopefully; I will be able to squeeze the circuit board into the smaller housing.

These are the housings before any prep work, there are some dents in the front housing, and someone drilled a hole through the side of the housing to install a switch.

I will wire brush the housings, try to fix the dents and extra hole, and repaint as necessary.  First I need to remove the internals and prepare them for LED lighting.  I'm going to use the same approach previously used on the 1949 Comrade.  Its been installed for over 3 years and I know it works with the Dynohub.  There is a wealth of information and opinions on-line for LED bike lighting.  The circuit I used for the Dynohub is a simple variation of more sophisticated options.  In addition to the LEDs, it uses only two components, a Bridge Rectifier, and a Capacitor.  Also needed is a Heat Sink for the high powered LEDs. From browsing the web, these seems to come in many variations, from commercial products to DIY versions using a bolt and some washers.  According to the "experts" a heat sink is needed to draw heat away from the LEDs to prevent damage.  I will make some heat sinks similar to what I used on the Comrade, but made smaller fit the Sport housings.  In addition; they will provide a mount for the LED's within the vintage housings.  These are the heat sinks made from aluminium rod to replace the bulbs, they are sized to be a friction fit within the original bulb housings.

Rear light heat sink.

Heat sink for rear light inserted into bulb holder.  The LED will be mounted to the face of the heat sink.
Front light heat sink

Front light heat sink inserted, the LED will mount to the face of the heat sink.

This is a patch to repair the hole that was drilled into the lamp housing by a previous owner.  With a little Bondo and some sanding and it will be unnoticeable.  I also had to shorten the screw that fits into the rear of the housing because it was interfering with mounting the circuit board.  I will use J-B Weld epoxy to affix it to the housing.

After Bondo and sanding

Shorten screw, will be epoxied to rear of housing

The next "LED Lighting" post will cover building the LED circuit board and mounting.  Please share your comments and experiences.

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