Fig. A: Drilled plastic disk for holding LEDs. Fig. B: LEDs
glued into the disk and wired together with the resistor.
Fig. C: Leads connected for power and switch. Fig D: LED
disk fit into the rubber end of the faucet hose adapter.
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.
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.
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
130 Make: Volume 14
Fig. E: Switch connected to the negative LED lead and
negative battery terminal. Fig. F: Rider’s view of the
headlamp hose-clamped above the bicycle handlebar
and the switch zip-tied underneath.
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.
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.
I made a second light for my girlfriend that has a better switch setup (page 129). 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 makezine.com/
MI T student Trevor Shannon ( trevorshp.com) has been
making things since he was young. Occasionally, those