When I bought it [from a weird old man..] it was equipped with front and rear bulb lights, powered by a dynamo.
As you maybe already know, this is not the best solution to light your way home at night: dynamo and inertia are enemies and the dim light of bulb lamps turns off as you stop at a crossroad.
After some months of sweat and darkness, I wanted to switch to a more efficient solution but I didn't like how modern LED torchs looked on my bike.
So I decided to create my own classical looking light.. with future inside.
Step 1: Stuff and Tools
- original rear light (free)
- chinese solar torch key-ring (2,5€)
- small toggle switch (1€)
- red LEDs stripe, I've taken it from another bike light (1€)
- hot glue gun
- tin wire
- soldering iron
- desoldering pump (optional)
- multister (optional)
- dremel (optional)
Step 2: Modify the Old Light
We need only the plastic case, the red reflector and the clear red cap.
Widen the side hole, where the wire from the dynamo used to be, until the toggle switch fits inside it.
If needed enlarge also the upper hole where the LEDs will be placed.
Step 3: Open the Solar Torch
You should find a circuit made of:
- a mini solar panel
- a rechargeable battery
- a switch
- a diode
- a resistor
this circuit is really simple but maybe you want to take some pictures of it before desoldering anything.
Step 4: Create the Circuit
Use the schematic in the image for references.
You can use a piece of protoboard if you want, but make sure that all the parts easily fit inside the light.
Switch's pins are inside an easily meltable piece of plastic, take your time soldering wire on them.
Step 5: Where to Put the Solar Panel?
Then I thought: "if cheap sunglasses can't stop solar radiations why should a clear red piece of plastic stop them?"
Time for science!
With the voltmeter I tested the performances of another little panel I have at my place, first under the direct sunlight and then covered with the reflector. There was almost no difference, so I decided to stick the panel directly on the inside of the reflector.
Of course vertical orientation is not optimal for solar panels, but actually it works!
Step 6: Put It All Together
Don't forget (like me..) the screw you need to hang back the light on your bycicle.
Stop the switch with its nut, use some hot glue on the inside to help absorb shocks.
With some hot glue secure the battery and the other components on the inside, the LEDs into the red clear cap and the solar panel on the reflector. Be careful not to cover the active side of the panel with glue.