Electronic help

del wrote:
I now have a DLumotec Oval and Seculite Plus. The dynamo I have, which
will eventually be replaced subject to funding, is a Union bottle job
(circa 1990). Can both these LED lights be run together without either
one burning out? Or should I use the old filament headlight as well?

If your old dynamo generates 3W at a nominal 6 Volts (and its the 0.5A of
current that matters, not the number of volts), then it is producing the
same as a standard B&M bottle model, and any other dynamo which meets the
long established German standard.

If not, and its producing too much current as the speed rises, then you have
problems.
(I had a Sanyo bottom bracket dynamo which used to produce too much current,
so fitted with a 1W rear bulb to prevent bulbs popping whenever I got to
18mph).


Connect the lights in series or parallel, with or without the filament
h/light? I used to run front and rear filament bulbs in series before
so that I'd know when the rear had burned out.

The new lights are 2.4W (front) and 0.6W (rear).
Connected in parallel that means a 3W load, matching the theoretical
generator power, which is how the makers recommend connection.

( if you connect the two in series, you'll put all of the 0.5A through the
rear lamp, which will blow quickly as its designed to take 0.1A. There is
also a chance you blow the front as well).


The packaging suggests that the overvoltage protection is limited,
especially in the Seculite, for the time that they will run on their
own should the other blow it's diode or break a wire or some other
fault. Would getting a voltage regulator (zener diode?) help?

Not sure it would help, as (AFAIK) they use a zener for protection already
:-).



- Nigel



--
Nigel Cliffe,
Webmaster at http://www.2mm.org.uk/

del wrote:
On Friday 06 Oct 2006 20:25 Nigel Cliffe, wrote:


The new lights are 2.4W (front) and 0.6W (rear).
Connected in parallel that means a 3W load, matching the theoretical
generator power, which is how the makers recommend connection.

( if you connect the two in series, you'll put all of the 0.5A
through the
rear lamp, which will blow quickly as its designed to take 0.1A.
There is also a chance you blow the front as well).

Where did you get this info? I couldn't find anything like it on BM
website or on the packaging for the lights.

Basic physics ( :-) ) , a rough idea of the German lighting regs, combined
with the fact that all B&M's 6V systems are interchangeable (eg. a filament
bulb front lamp carries a 2.4W bulb (*), this can be matched to a LED tail
(0.6W) and the same generator (dynamo), therefore the new LED front, which
matches the same LED tail and same generator must also be 2.4W).


However, the B&M website does tell you how to wire their lights to their
generators, you just have to piece all the manuals together. They are in the
"downloads" section.



(* when shipped from maker. Some riders, including me, swap the 2.4W to 3W
and run a front light only, and battery powered LED rears).


- Nigel


--
Nigel Cliffe,
Webmaster at http://www.2mm.org.uk/

In article
Nigel Cliffe wrote:
del wrote:
I now have a DLumotec Oval and Seculite Plus. The dynamo I have, which
will eventually be replaced subject to funding, is a Union bottle job
(circa 1990). Can both these LED lights be run together without either
one burning out? Or should I use the old filament headlight as well?

If your old dynamo generates 3W at a nominal 6 Volts (and its the 0.5A of
current that matters, not the number of volts), then it is producing the
same as a standard B&M bottle model, and any other dynamo which meets the
long established German standard.

If not, and its producing too much current as the speed rises, then you have
problems.
(I had a Sanyo bottom bracket dynamo which used to produce too much current,
so fitted with a 1W rear bulb to prevent bulbs popping whenever I got to
18mph).

But less light at lower speed - Sanyo fitted a voltage regulator to the
later model, or you can buy a voltage regulator to add to any dynamo,
which permits full brightness at lower speeds but prevents over-voltage
at higher speeds.

Connect the lights in series or parallel, with or without the filament
h/light? I used to run front and rear filament bulbs in series before
so that I'd know when the rear had burned out.

The new lights are 2.4W (front) and 0.6W (rear).
Connected in parallel that means a 3W load, matching the theoretical
generator power, which is how the makers recommend connection.

( if you connect the two in series, you'll put all of the 0.5A through the
rear lamp, which will blow quickly as its designed to take 0.1A. There is
also a chance you blow the front as well).


But if you connect them in series some of the voltage will drop across
one lamp and some across the other, so neither sees the full 6V and the
total current will be lower (and neither lamp will operate at its design
output).