Introduction: Solar Powered Vintage Rear Bycicle Light

Picture of Solar Powered Vintage Rear Bycicle Light

I have an old bycicle and I really like its classical design.

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

Picture of Stuff and Tools

you need just few materials:
- 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€)

and tools:
- scissors
- screwdriver
- tweezers
- hot glue gun
- tin wire
- soldering iron
- desoldering pump (optional)
- multister (optional)
- dremel (optional)

Step 2: Modify the Old Light

Picture of Modify the Old Light

First of all you have to open the old light and remove bulb and its metallic contacts and support.
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

Picture of Open the Solar Torch

Open the torch and pick out the electronic stuff.

You should find a circuit made of:
- a mini solar panel
- a rechargeable battery
- a switch
- LEDs
- 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

Picture of Create the Circuit

Desolder the components from the pcb and resolder the circuit using the new switch and LEDs.
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?

Picture of Where to Put the Solar Panel?

I wanted to preserve the vintage style of my bike, so at first I decided to hyde the solar panel inside the light case and take it out only when in need of a charge.
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

Picture of Put It All Together

Fit the circuit inside the light, there should be enough room for everything.
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.

Step 7: Done!

Picture of Done!

Easy, nice and effective :)

Step 8: To Be Continued..

Picture of To Be Continued..

preview of next instructable!

Comments

suppamanIII (author)2013-08-09

why not 2 leds in series? It's more efficient with one current you light up 2 leds

olmon (author)2012-09-09

Really excellent and practical instructible. I have been planning on installing solar lighting on my Rhoades car & plan to use a solar spot-lite kit that just happens to have 4 lites in the kit so all I have to do is mount them and make red lens for the rear lites. The solar charger already has an on/off switch so I got lucky there.

jeffeb3 (author)2012-07-16

Maybe something is just missing from the schematic, but typically, you would either wire the LED's in series, or give each one their own resistor. Unless they are perfectly matched, you will get dim ones and bright ones with them in parallel with only one resistor. It's possible there is some resistance built into the LEDs. Maybe that's why you aren't having problems.

eriol (author)jeffeb32012-07-16

you are perfectly right, this is not the best solution.
Anyhow in the schematic is shown the circuit as it was in the original torch and as it is in the final result. Breadboarding the project showed no problem with the wiring of the recycled red LEDs, so I've used them this way. As the sayng goes "chinese engineers knows better!", right? ;D

Caledo (author)2012-07-16

Great !!!

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