Vintage Bike Lights to LED Conversion




About: I'm a swiss guy, living in germany. I used to be a teacher, became a theatrical propsmaker, now I'm a teacher again. I love hacking, altering, improving and of course building things! And sorry guys, I can't...

In early summer 2013 I bought this beat down bicycle, made by NSU (germany). According to the frame number it was built around 1952. The idea was (and still is) to create a bike worthy and capable of towing my red kids-trailer.

This instructable is only about the lights of this bike. There will come some more ibles about other parts of the (still ongoing) project.

The idea here was to fit battery powered LED's into the existing lamps at a low budget. Because when towing a trailer I don't want to spend energy on creating electricity for my lights!

If you're interested head over to step 1 for parts...

Step 1: Parts and Tools

I had two cheap LED-lensers lying around on one side and the bikes old lights, dynamo and a toolbag on the other side. I had no more use for the dynamo, so I sold it on ebay and the toolbag was to beat down (torn straps) so I put it aside.

The lensers were taken apart to get the LED's, the leftovers tossed.

Not pictured: two-wire cable, switch

As tools I used mostly standard equipment. Nothing special here apart from a soldering station and terminal cables: pliers, screwdrivers, side cutters, pen and paper, knife, ...

Step 2: Tail Light

First I did the tail light. To build in the LED's I had to open it first. I did this by bending open the metal ring which was holding the glass with a small screwdriver. Be careful to avoid to much damage here.

I was lucky, the circuit board with the LED's was a perfect fit. So I soldered on the wires (the clear glue is just to add extra protection and to reduce strain on the soldering points) and glued the circuit board into the housing. After that I put glass and metal ring back on place and bent the ring back (again with a screwdriver).

The hole in the back of the housing I closed with some foam, covered with black taped. Not that beautiful, but it works.

Step 3: Front Light

To get the LED into the front light I had to cut the reflector. Usually I don't like to destroy old things but this reflector had it's best days behind, so the decision was not to hard. After it was cut, I again glued the circuit board to the reflector (after the soldering of the necessary wires).

Step 4: Cabling

After the LED's were mounted in their housings I had to think of the proper cabling. My knowledge of electrical system is very basic (so no resistors and stuff like that). I did a rough sketch and tested it with some terminal cables I had around.

After testing a few options I had found a way to make good use of my on-off-on switch: (front and tail)-(off)-(front-only). I know that 9V is probably to much juice for my LED but as long as it works I don't worry about that.

After testing I finished the cabling with wire in proper length and some nice plugs.

Step 5: (Re)assembly

With all the cabling done it was time to fit everything in.

The frontlight was big enough to hold the reflector and the 9V battery. There was already a small hole, perfect for the switch, and another gap to run the cable trough (had to cut off the plug already in place...). Be sure to make a knot in the cable on the inside of the lamp to reduce strain.

All plugged an soldered I put shrink tubes on switch an plug joints, just to be sure, that everything stays, where it's supposed to be.

To avoid the 9V battery rattling around in the light housing, I fitted a piece of foam to hold it in place.

Step 6: Results

Finally I put the lights back on the bike. The cabling almost disappears and the light is really bright.

So one step of many done on the bike. On to the next one.....

If you want to follow the project and know some german or want to struggle with google translator, you can find more pictures and information here

If you liked this instructable, feel free to vote for me in the contests! ;-)

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    16 Discussions


    7 months ago

    Nice post does the front light always stay on?

    1 reply

    Reply 7 months ago

    No there is a switch...

    Nostalgic Guy

    1 year ago

    I recently had to replace the bulb on my ageing electric bike so rather than go with a humble tungsten bulb I modded it to a 50 smd led bulb similar to this one, not so much for the beam which is sadly wasted owning to the rubbish lens on the original light (I have a pair of Cree lights for beam use so I can see where I'm going in pitch darkness) but to ensure that the seemingly blind drivers in my town have no excuse not to see me coming. Best upgrade among many that I have done yet on my humble old lead acid driven workhorse bike.


    3 years ago

    thanks buddy i shall be using this fantastic idea on mine


    4 years ago on Introduction

    I've have an old bike light set and dynamo that I was planning on doing an 'ible for, for ages. Damn, you've beaten me to it!
    Good job though!

    I'm using a smaller CREE LEDs for mine and powering it from some rechargeable 3.7v batteries. I'll post some pics when I'm done!

    2 replies

    wow forgot about this! the project has also sadly got put on hold.
    I didn't want to use the dynamo as (not sure where you're from) in the UK bike lights are not road legal if they switch off when you stop at traffic-lights so i wanted to do something that would have a battery. To make the dynamo charge the battery would be possible but I needed something clever to stop it over-charging and never got that far. the plan was to carry a spare charged battery and not worry about the dynamo.
    I should get back on it and get it working for winter! Cheers


    4 years ago

    very cool use for some classic lamp enclosures

    Ghost Wolf

    4 years ago on Introduction

    It would be cool to make or get a circuit to flash the rear light at least. It could save on power consumption.


    4 years ago on Introduction

    Too bad I don't have an old bike in the garage... Makes me want to build a light right away.


    4 years ago on Introduction

    I'm restoring a 70 years old bike in these days. It was used by my girlfriend's granny when she was 15! :D

    I think that a mod like this one can be really useful! Thanks for sharing! :D


    Reply 5 years ago

    there are special led's out there for use with a dynamo, but the cost around 7 or 8 € a piece....