Lights for Azub 4



31.12.2005
Many questions about my bike's lighting finaly made me write this description of that terribleness I use on my bike.
I use normal flash lights you can buy in every cycling shop, white Smart on the front end and red Cateye on the rear. Then there is a halogen light under the handlebar, Cateye 4.8V 500mA, four AA cells. Partially it illuminates front wheel, fork and my left foot, but it works. Long time ago it even was enough for me.
For the night part of K24 (24 hour amatheur marathon) in 2004 I tried a 1W Luxeon and I liked much. This year i bought new accumulator (5xAA NiMH Sanyo 2500mAh => 6V). I considered the energy vented out in the series rezistor vasting, so I used 20 yellow superbright 5mm LEDs in series with one 1W Luxeon. When on full power, there is a current approximately 17,5mA flowing in each diod, 350mA in Luxeon. That's accurate at 6V, but fully charged accumulator has more than it's nominal voltage and is able to fry the Luxeon. That's the reason for one more resistor 1 Ohm made of ten 10 Ohm resistors (nothing smaller with enough wattage was at home:-)).
The role of those yellow LEDs is to illuminate the wheel spokes (3 from each side of each wheel) so they look cool when rotating. Then they illuminated my starting number so everyone can see when that crazy rider on strange bicycle shot down by a lorry two days before the race is approaching and his nuber is 13, quite conveniently. Four LEDs were on each side of the luggage rack where the fabric number was. In October I finaly disassembled this part. Two LEDs were moved to each side of the handlebars, one into the front mounting hole of the seat/frame assembly and one into the unused mount hole of the rear shock.


It's quite crazy, looks like christmas tree and many are laughing (allmost everyone, actually), but anybody can deny it's VISIBLE on the road in the night!
Luxeon is mounted by two bolts to a small radiator (the black metal on the pictures) and the same bolts hold it all on the small sheet of stainless steel (0,5mm). Then it's mouted to the frame dropout meant for mounting an adapter for headlight on the top end of the derailleur tube. The bolts and soldering points are masked by white reflexive sticker with round hole for luxeon. That sticker was complicating taking the photos, because it reflects the flash, surprisingly. The cable is hold by unused dropout for derailleurs cable, then under the frame to the rear.

This is how it looks turend on (photographed without flash so the reflexive stickers don't do any anoying efects):

I wanted to add a rear flashlight that would be visible even during the day. When (almost) every car has its lights on in winter, cyclists become invisible on the road. Espetially in the light morning mist or so.
I used an old flashligt that was worn out beyond repair. I took out all the entrails and put in three red LED diodes Paralight. They cost me 39Kč per one, their nominal current is 150mA. Red Luxeon would be usable, but it has smaller area, is more expensive and would be more difficult tu put in. Paralights are for SMD technology, but it's not difficult to put them on universal PCB. This is how it looks:

The cable is taken out through the hole that remained when the original on/off button was taken out. The flashing circuit is located near the accumulator and switches under the seat. It's just simple hard astabile flop made from two tranzistors, on the universal PCB again. It's tuned to cca 1/3 duty cycle and when the diodes are on there is about 100mA flowing through them. Resulting overall consumption is cca 35mA. That not small number, but one cannot believe how powerfull this light is unless he sees it himself. Next photos are taken without flash in a room during a day. Firstly only the upgraded one, then both original Cateye and the upgrade:

Second photo was taken directly in the axis of the middle diod of the lower light, that's why it looks brighter. I was surprised that the difference in intensity is so small in the photo. For naked eye it looks like the batteries of the lower lights gone weak when you turn the higher one on. And the bought flashlight was chosen because of how much it lights and it wasn't cheap.
I was too lazy to draw the schema on PC so I just draw it simply on the paper. I hope it's readable:

Just tu make sure: rezistors from the left: 100k, 390k, 820, 4k7. Capacitors are elecrolytes 2,2µF and 100µF. Tranzistores can be many types, I use BC337-40. Three LEDs in series are Paralights in the rear light, indeed. On the right is Luxeon, everything is simple there. Each part has it's own switch. I was too lazy to design my own PCB for such small thing so it's all on univeral ones. As you can see, it didn't prevent me from some degree of miniaturization:-). Tha flashing circuit is naked just for the photo, normally it's covered with insulation tape. Water is harmles in 6V circuitry, anyway, but i need to prevent it from touching some coductive part of the frame. Accu is in thin foam and black insulation tape. Switches fit to the holes designed for mounting seat.

Next step is board with panelmeter and control lights showing what is on or off.