light turns off computer

pbamf

Now the dark nights are here when i switch on my Niterider 650 light, on any setting it stops my Cateye wireless computer from picking up a signal from the sender. Ok you can't see the speedo in the dark but it would be nice to see how far you've been when finished. Any ideas

macleod113

if the light is LED they can cause interference causing the issue you have found. the cheap option would be to wrap your light in foil :-s

cougie

Have you tried moving them further apart ?

team47b

Take the computer off its mount and put it in your pocket

dowtcha

This is from the electric magnetic field (EMF) from the light. Try and keep them as far away from each other. If you are using flashing mode try constant beam as flashing will cause a pulsating emf.

pbamf

Ok thanks for the replies

rodgers73

I had this problem. Eventually I bought a cheap wired computer for the winter or used my Garmin instead.

kingofthetailwind

My Cree Solarstorm and Macro Drive both interfere with my wireless computer, no matter how I arrange them. I use a handlebar extender.

http://www.sjscycles.co.uk/accessory-fi ... s-dept785/

markhewitt1978

My Cateye light does this to my Cateye computer. When in flashing mode it shows me as doing a constant 12mph plus whatever speed I'm actually doing.

Dave_P1

I have the same problem with my cateye computer and front light, except the computer only stops when the light is on low & medium mode, and not the high mode which I find a little odd.

Ouija

Dave_P1 wrote:

I have the same problem with my cateye computer and front light, except the computer only stops when the light is on low & medium mode, and not the high mode which I find a little odd.

PWM (pulse width modulation).

Most modern digitally controlled LED lights don't vary brightness by varying voltage but by turning the light on and off very quickly (PWM). Too quick for the human eye to detect (though not most animals, who see a LED on low/medium power as a disco strobe effect which is why they just stand there and stare at you until you almost run them over as it looks like a series of unconnected images that don't form a animation of a cyclist coming towards them in their brain).

From an electrical point of view, that rapid turning on/off can cause havoc with nearby devices such as a wireless bike computer. On full brightness the light isn't using PWM to dim the light but simply providing a full, constant current at a constant ampage, so no interference.

The fans in your computer work the same way. Old fans used to just lower the voltage from 12v downwards to slow the fan down. But at 6V the fan would struggle to work at all and come to a stop rather than spin slower. Modern fans stutter (PWM) a 12v current to vary speed. Lengthen the PWM timing so that the power is off for a little longer than on and the fan loses speed and can tick over at a much quieter/slower speed than old analogue controlled fans. And much the same principle applies to LED's with the constant stuttering of the power preventing the emitter from glowing up to it's maximum brightness.

You can test if your light is using PWM to control brightness by simply pointing it at your spinning bike wheel in the dark. On full the spokes should rotate as normal. On Low/Medium they will appear to spin backwards or break up into a million spokes (much as they do when recorded by television cameras at only 25ish frames a second).

Dave_P1

Thanks for taking the time out to explain it, much appreciated.