How-To Tuesday: Mini bike light

Bikes Fun & Games Technology
How-To Tuesday: Mini bike light

Photography by Trevor Shannon and Katie Dektar

Make an easy LED headlight from a garden hose adapter.

By Trevor Shannon

I wanted to build a small, bright, and durable LED light for my bike, and I read online that plumbing parts work well as housings. So I made a 3-LED headlamp that’s enclosed by a 3/4″ hose faucet adapter and powered by an outboard battery pack.

1. Make the LED mount.

To hold the LEDs, I used some scrap translucent plastic. Using a drill press, I marked an outline on the plastic sheet by cutting partway through with a 1 1/4″ hole saw. I drilled three 5mm holes inside it for the LEDs, then finished cutting out the disk with the hole saw.


Fig. A: Drilled plastic disk for holding LEDs.

Fig. B: LEDs glued into the disk and wired together with the resistor.

Trim the edges of the disk until it fits snugly in the rubber side of the hose adapter, stretching the rubber a bit. I used a grinder, but you can also use a file or sandpaper (Figure A, following page).


  • White 5mm LEDs, 3.6V, 20mA (3) part #276-320 at RadioShack, or cheaper from or other online suppliers
  • 15Ω resistor I determined the resistor’s value using a formula described in
  • 3-AAA battery holder (1) with batteries (3)
  • Small SPST toggle switch I used a micro-mini toggle, RadioShack #275-624, for a second, more streamlined version of the light.
  • Insulated wire, electrical tape, and super glue
  • 3/4″ garden hose faucet adapter clamp style
  • 1/4″ hard translucent plastic small sheet or scrap
  • 1 1/4″ hose clamp and 1 extra clamp
  • Soldering materials
  • Drill press with 5mm bit and 1 1/4″ hole saw
  • Grinder, file, or sandpaper

2. Connect the LEDs.

Super-glue the LEDs in the disk’s holes, arranged so that all their short (negative) leads point toward the center. Bend and solder together the short leads, then the long (positive) leads, avoiding any short-long contact. Solder a 15Ω resistor to the positive side (Figure B), and clip the excess length on all leads. Keep the whole affair small, with leads as short as possible, so it will all fit in the housing.


Fig. C: Leads connected for power and switch.

Add wires to connect to the switch and power (Figure C). Solder one to the negative leads and the other to the resistor, marking which one is which.

3. Put the light into the housing.


Fig. D: LED disk fit into the rubber end of the faucet hose adapter.

Fig. E: Switch connected to the negative LED lead and negative battery terminal.

Fit the disk into the rubber end of the adapter, with the wires exiting the threaded hole in the back (Figure D). The rubber held my disk well without glue, but otherwise I would suggest a thin film of epoxy. I cut off just enough extra rubber to make a shim which, along with some electrical tape, holds the wires in back and keeps out water and debris.

4. Wire the circuit.

I mounted the light on top of my handlebar, the switch against the stem, and the battery pack behind the head tube. Trim the wires to the right lengths to connect these, leaving enough slack to let you turn the handlebar. The switch connects between the negative LED lead and negative battery terminal, and the positive LED lead connects to the red, positive battery terminal (Figure E).

5. Attach the light.


Fig. F: Rider’s view of the headlamp hose-clamped above the bicycle handlebar and the switch zip-tied underneath.

I mounted my light by interlocking the hose clamp that came with the adapter with a second clamp around the handlebar. For the switch and battery pack, I used zip ties, and added more to hold the wires against the frame (Figure F). Make it all tight so that nothing falls off if you go over a big bump.

Version 2

I made a second light for my girlfriend that has a better switch setup. I mounted a micro-mini switch in the hose adapter’s hole in back, and routed the wires out a hole drilled through the side. This eliminates the big switch zip-tied to the handlebar.

You can see a wiring diagram at

MIT student Trevor Shannon ( has been making things since he was young. Occasionally, those things work.


Make 14

From MAKE 14 – Page 129. To get MAKE, subscribe or purchase single volumes.

10 thoughts on “How-To Tuesday: Mini bike light

  1. Dave C. says:

    This looks like a great low-power notice light. Probably fine if there are streetlamps but not so good for avoiding potholes and we leaves.

    I made my own high-power bike light a few years ago. I bought a 15W 45 degree spread light on a spike that you usually stick in the ground. I removed the spike and hooked it up directly to a sealed lead acid battery for a really bright light with excellent coverage. The bulbs are incandescent so they aren’t very fussy about voltage. The bulbs are also standard replacements.

  2. HT says:

    Looks nice, but I’d like to see a mention of waterproofing. Is that even necessary, I wonder?

  3. brian says:

    how bright is this is there anyway you can measure how many lumens it has?

  4. Jaffa says:

    This is a great little light very cool. Makes me want to give this a go.

    Has anyone researched making a light LED that will run off of a common old car battery that could be used.

    The two main things is 1). that’s it uses least amount of electricity. 2). That is’ bright enough for a common room doesn’t need to be supper bright. Just Warm Light.

    If you or anyone would ;like to do a project on this that would be cool!!

    If i can get a prototype idea of how and what to use to make one i will put a heap of them in my 40 foot shipping container.

  5. says:

    This type has no physical characteristics which can be
    dangerous because they build up a tolerance steel construction
    nz inc in your body. There are many things you will need staff.
    This means toward more complete life and more perfect functioning; and
    that will just water the plant. He certainly displays this mentality
    of ‘if I keep stalling then eventually things will blow over’.
    My hotel boomed No, they come running. The misplaced object
    of his affection iis also a kshetra.

Comments are closed.

Discuss this article with the rest of the community on our Discord server!

current: @adafruit - previous: MAKE, popular science, hackaday, engadget, fallon, braincraft ... howtoons, 2600...

View more articles by Phillip Torrone


Maker Faire Bay Area 2023 - Mare Island, CA

Escape to an island of imagination + innovation as Maker Faire Bay Area returns for its 15th iteration!

Buy Tickets today! SAVE 15% and lock-in your preferred date(s).