Every fall I start thinking of how to increase the visibilty of my bicycle as well as being able to see where I'm going, since the sun goes down early - I'm more likely to be out riding when it's dark.
I've been toying with halogen lights with a little success, but nothing I was totally happy with. I tried driving the halogen with two 6v RC car batteries in series but found that although it was fairly bright, it didn't last long at all. I've learned that ideally you want to run a halogen with 14v (not 12v) and it will require two 14v battery packs wired in parallel to get a half decent run time. That's a lot of batteries, which goes against my ideal of making a cheap system. It takes a while to charge all those batteries too, which is another negative towards that design.
However, I have a background in electonics and a large amount of various bits of junk... And, to quote Thomas Edison: To invent, you need a good imagination and a pile of junk.
Amongst my junk parts, I had some resistors, capacitors and luckly enough a 555 timer microchip. I took apart my rear LED flasher (the mounting clip snapped off earlier this year) and removed the five super bright amber LEDs from it. I also had some blue/white LEDs scavenged from dollar store lights.
I picked up a small project board and a 4xAA battery holder from The Source. I reused the plastic container that housed my 12v batteries previously for this project - it originally came with some teeth whitening strips which, I must admit, I bought the particular brand I did just for the plastic container.
The container has two pieces, the outer casing and an internal tray. I removed some plastic bits that where in the way, and mounted the project board on some nylon mounts I had. On the board I soldered up a standard 555 timer circuit (details to be provided later if necessary) with 7 LEDs that flash alternatively.
Cut into the side of the case and hot-glued in is the partially reflective red plastic cover from the original rear blinky, but I had to hack the nylon mounts slightly shorter to line up the LEDs properly.
The switch is a push-on/push-off micro switch that was part of the dollar store lights... I just clipped off part of the mounting board that I didn't need (and was in the way) and glued it to the tray. It pokes out through a hole in the bottom. On the underside of the case, I glued in a piece of inner tube, partially pushed through the hole. This allows me to press the button, but keeps the switch protected from being exposed to the elements.
The double white wire you can see running away from the circuit is the lead to the LED headlight which I am still constructing. The headlight will be based partially on the 5xLED internals from a Raleigh headlight combined with eight more of the bright blue/white LEDs from the dollar store lights.
All assembled and turned on it looks like this:
I have a video that I'll upload to youtube at a later date, showing the lights flashing. This light is very bright and noticable. The idea is to mount it to the underside of the rear rack.
Just a teaser for the headlight - I have a casing made of PVC pipe connectors that will house it. In the picture what you see is the LED holder/reflective portion of the Raleigh headlight mounted in a chopped up portion of the top of a pop bottle. The holes in the plastic that you can see is where the eight LEDs will poke through, I'm just waiting for the glue to dry that is holding the aluminum foil on. In a few hours I'll be able to punch the holes through the foil and solder the LEDs into it. I'll post some more pictures in a few days - I had to rush to take these pictures since the owner of the camera wants it back tonight.
Just thought I'd share this - less of a how-to, since not everyone has the spare parts I had kicking around, more a bit of inspiration and example of what you can do with what you can find around.