Alien Eye Bicycle Helmet Blinker Light

Before I developed the Alien Eye, I was riding with a 3W Tubelight and a cheap three AAA battery LED head lamp strapped to my helmet.   While riding with the helmet light I felt had fewer close calls with autos at intersections.  I had the feeling that I was able to be seen better since the light was much higher due to being on the helmet.  In some cases the light can be seen by oncoming traffic over the cars in front of me.  The most important thing to cycling at night is to be seen by the cars and by pedestrians.   For this you do not need a powerful light, but something that attracts their attentions.   I have found that a blinking light draws a lot more attention from drivers than a non-blinking light.  I find a blinking light extremely useful in drawing attention to me from cars that are merging into my direction of travel.    A quick turn of the head and the blinking light catches the driver's eye and then he knows you are there.  A blinking light also cuts power usage.   This lamp only draws 100 ma when it is on compared to the 530 ma the 5W Edison Opto spot draws.    In the blink mode you should not have to worry about having enough power to get home before the battery runs out.    Run with a 50% on/off duty cycle, you will only need on average 50ma to drive the light.  With 2500 mah batteries you could ride 50 hours before needing to recharge your batteries.

After I developed the Alien Eye and found the Cateye helmet mount I wanted to develop a low power helmet blinker light I could use with the same 12 V power source as the Alien Eye and the same mounting system.  The 5W lamp in the Alien Eye was too powerful to use in a blink mode and after writing the LED manufacturer the Edison Opto lamp is not made to be PWM driven so I could not reduce the light intensity in a blinking mode using the 5W lamp.

There are plenty of low cost 1- 2 Watt white LED MR16 lamps on the market.   I chose to use a standard sealed 1.2 Watt, 12V LED that was on sale at Lidl for 4.99€.   Olaf my friend from work is also my electrical guru and I asked him if he could make me a driver circuit to blink my light.   After the weekend, Olaf gave me light back with a small circuit board soldered on to the lamp terminals with leads for the battery connections.   All I needed to do was finish  the lamp in a similar procedure to the normal Alien Eye kit design.

The circuit diagram for the blinker can be seen below at the bottom of this page.

I attached the base and the power connector with 5 minute two part epoxy putty.  I had some left over Milliput black two part epoxy putting for the outer shell.   Milliput cures too slowly for the parts where I want to fix a position for alignment.   I used Milliput for the final shell since I did not want to risk anything going wrong with the electronics if I used Fimo and baked the lamp in the oven.  I decided I did not need to use a switch since if the light was mounted on the helmet it would be always on anyway.

Here are some pictures of the lamp during construction.