Re: For those who believe in electricity

Frank Krygowski <frkrygow@sbcglobal.net> wrote:

On 4/8/2025 8:56 PM, Frank Krygowski wrote:

 
The switch is the tiny white box toward the bottom of this photo:
https://www.flickr.com/photos/16972296@N08/54435279894/in/dateposted-
public/ just below "3R 46 16V" which is probably a capacitor. The black
pushbutton sticks out downward in the photo (or backwards, in the
mounted headlight) and looks odd in the photo, again because of
reflections. That switch is about 4.5mm x 2.5mm x 1.8mm tall. I removed
the switch from the circuit board.
 
I had assumed it was a toggle, but it seems instead to be a momentary
switch. It connects to five tiny solder pads. The two big ones, at the
"bottom" of the switch in the photo, are just for fastening it to the
board. At the "top" face in the photo are three very tiny pads, call
them A, B and C.
 
Playing with a jumper wire ending in two sharp pins, I found that
momentary contact from A to C changed the state of the light, on to off
to back on, etc. A to B did the same. I had to be careful to touch
fairly quickly and not bounce.
 
At last check, the light is in "on" state. I think if I don't disturb
things, it should stay in that state, and I can try reassembling and
testing it on the bike. I've got other stuff to work on tonight, so I'll
get back to it tomorrow.

 
More bench testing this morning. The headlamp started right up,
perfectly consistently when driven by the dynamo spun with my drill
press. Momentarily jumping A to C (or B) of those switch solder pads
toggled the lamp on or off while running the dynamo. Shutting down the
dynamo put the lamp into "standlight" mode. In that mode, with no
voltage input, jumping A to C turned off the standlight. Applying power
turned the lamp back on, no switching necessary. It seems the headlight
is operating as it should.
 
I'm convinced the problem was that faulty switch, probably with internal
parts rattling around enough to occasionally toggle that A to C or A to
B contact. I suspect it will work fine if I successfully reassemble it
without the switch.
 
It's still slightly worrisome, because a headlight really does have to
be reliable. Maybe I'll carry a little battery light as a spare for a
while. I often do that anyway when night riding with others, because of
so many incidents of other folks' headlights failing on rides.
 

Who on earth to you ride with that have light failures? I’ve never had a
light fail on the ride, I’ve had in the early days ooh batteries is a bit
tired as the light dims as the battery can’t hold the voltage any more, and
had cheap lights mounts and so on start to wear.

I still have multiple lights that I’ve upgraded from which still work, but
time and technology has moved on.

Likewise I see a lot of bikes, and meet up with folks for a Wednesday night
ride, most weeks it’s not a thing that is common, it’s not impossible but
definitely rare.

Roger Merriman