When do blinking lights become just plain annoying?

On Mar 22, 1:40*am, James wrote:


There is some, albeit poor, current regulation by most bicycle
alternators, but not voltage regulation as you know.

I'm curious about your claim that current regulation by these things
is poor.

James, why not try some measurements? Both current and voltage, into
(say) either a matched halogen bulb or a power resistor. Give us the
results.

- Frank Krygowski

Frank Krygowski wrote:
On Mar 22, 1:40 am, James wrote:

There is some, albeit poor, current regulation by most bicycle
alternators, but not voltage regulation as you know.

I'm curious about your claim that current regulation by these things
is poor.

Look at the output from a semiconductor voltage regulator. The output
may be within 0.1 or 0.01% of the desired output voltage.

JS.

Frank Krygowski wrote:
On Mar 22, 1:40 am, James wrote:

There is some, albeit poor, current regulation by most bicycle
alternators, but not voltage regulation as you know.

I'm curious about your claim that current regulation by these things
is poor.

James, why not try some measurements? Both current and voltage, into
(say) either a matched halogen bulb or a power resistor. Give us the
results.

http://www.jim-easterbrook.me.uk/cyc...o_limiter.html

JS.

On Mar 22, 5:08*pm, James wrote:
Frank Krygowski wrote:
On Mar 22, 1:40 am, James wrote:

There is some, albeit poor, current regulation by most bicycle
alternators, but not voltage regulation as you know.

I'm curious about your claim that current regulation by these things
is poor.

Look at the output from a semiconductor voltage regulator. *The output
may be within 0.1 or 0.01% of the desired output voltage.

But you don't need anything like that precision to run a halogen
headlamp. Hell, your car's voltage regulator isn't that precise.

I'm afraid you're back to your previous thinking - that any minuscule
"improvement" in anything relating to bicycles is absolutely
critical. You're like the student who puts a tolerance of 0.001" on
the diameter of a hammer handle!

- Frank Krygowski

On Mar 22, 5:12*pm, James wrote:
Frank Krygowski wrote:
On Mar 22, 1:40 am, James wrote:

There is some, albeit poor, current regulation by most bicycle
alternators, but not voltage regulation as you know.

I'm curious about your claim that current regulation by these things
is poor.

James, why not try some measurements? *Both current and voltage, into
(say) either a matched halogen bulb or a power resistor. *Give us the
results.

http://www.jim-easterbrook.me.uk/cyc...o_limiter.html

Nice try, but: He didn't give measurements of the current nor the
unclipped voltage vs. road speed, which is what I suggested you
measure. He's assumed certain values of unclipped voltage and
approximately computed the corresponding clipped voltage, based on his
computed generator inductance.

Here are the actual measurements I got, again, using a lab-grade true
RMS meter, with a bog-standard Union bottle generator:

8 mph 10 12 14 16 18 20 22 24 26
mph

5.40 5.80 6.00 6.16 6.30 6.36 6.41 6.45 6.48 6.48 Volts

The general rule of thumb is that halogen bulbs operate best within
10% of their rated voltage.

Here are the current readings we got, in amperes, at those same
speeds:

0.44 0.47 0.49 0.51 0.52 0.52 0.53 0.53 0.53 0.53

From 12 mph to 26 mph, current is constant within a few percent.

Now: Do you own a meter? Why not take some measurements to see if
you match our results? It's really not that hard!

- Frank Krygowski

On Mar 22, 6:30*pm, Frank Krygowski wrote:
On Mar 22, 5:12*pm, James wrote:

Frank Krygowski wrote:
On Mar 22, 1:40 am, James wrote:

There is some, albeit poor, current regulation by most bicycle
alternators, but not voltage regulation as you know.

I'm curious about your claim that current regulation by these things
is poor.

James, why not try some measurements? *Both current and voltage, into
(say) either a matched halogen bulb or a power resistor. *Give us the
results.

http://www.jim-easterbrook.me.uk/cyc...o_limiter.html

Nice try, but: *He didn't give measurements of the current nor the
unclipped voltage vs. road speed, which is what I suggested you
measure. *He's assumed certain values of unclipped voltage and
approximately computed the corresponding clipped voltage, based on his
computed generator inductance.

Oh, another serious problem with Easterbrook's page: If you install
zeners, you don't put them in series back to back, as he claimed. You
put them in parallel, facing opposite directions. In series, you'd
get no current flow until the voltage exceeded the zener voltage (plus
the forward diode voltage) which is vaguely opposite of what you want.

Looks like Easterbrook didn't do measurements either.

- Frank Krygowski

Frank Krygowski wrote:
On Mar 22, 5:08 pm, James wrote:
Frank Krygowski wrote:
On Mar 22, 1:40 am, James wrote:
There is some, albeit poor, current regulation by most bicycle
alternators, but not voltage regulation as you know.
I'm curious about your claim that current regulation by these things
is poor.
Look at the output from a semiconductor voltage regulator. The output
may be within 0.1 or 0.01% of the desired output voltage.

But you don't need anything like that precision to run a halogen
headlamp. Hell, your car's voltage regulator isn't that precise.

Obviously. The voltage regulator on a car alternator is probably not
that precise, but far more precise than the regulation provided by the
internal inductance of the bicycle dynamo. I expect a car alternator
regulator to regulate the output voltage to about 2%. Most even have
temperature compensation so that the battery receives less float voltage
as the temperature increases in the engine bay.

Hence, by comparison, I'd say the bicycle dynamo regulation is poor.

Whether or not the bicycle dynamo regulation is sufficient to safely run
a halogen headlamp without external regulation, depends on the nominal
rating of the dynamo, the regulation of the dynamo in question, how the
halogen bulb is rating, and the wires used to deliver power too it.

I recall someone advising me to use heavy cables to power spotlights on
my car, and a relay to switch them. The idea being that the lower
voltage drop to the bulb would make them brighter and whiter. Certainly
this was the effect, however the frequency of replacing bulbs also
increased significantly. I doubt that there was a 10% (1 volt perhaps)
increase in voltage, but the burn out rate of the bulbs was markedly
increased.

I'm afraid you're back to your previous thinking - that any minuscule
"improvement" in anything relating to bicycles is absolutely
critical. You're like the student who puts a tolerance of 0.001" on
the diameter of a hammer handle!

I'm afraid you're back to your old tricks too. No wonder you annoy people.

JS.

On 3/22/2011 2:12 PM, James wrote:
Frank Krygowski wrote:
On Mar 22, 1:40 am, James wrote:

There is some, albeit poor, current regulation by most bicycle
alternators, but not voltage regulation as you know.

I'm curious about your claim that current regulation by these things
is poor.

James, why not try some measurements? Both current and voltage, into
(say) either a matched halogen bulb or a power resistor. Give us the
results.

http://www.jim-easterbrook.me.uk/cyc...o_limiter.html

It's so wasteful to use a linear voltage regulator like a zener diode.
You're just bleeding off the extra power as heat. A DC to DC switching
regulator is more efficient, but you have the losses of the AC to DC
conversion in addition to the losses in the switcher.

The LED lights are ideal, the faster you ride the more power you
generate and the brighter the lights (this is for proper LED lamps, not
just attaching LEDs directly to the dynamo.

Most of the MR16 Cree LED lamps are rated at 8-15V AC or DC, but in fact
will operate at lower voltages, so they are suitable for dynamo use.

While you're probably slightly better off with one of the lamps like
http://www.ledshoponline.com/mr16_t-type_cree_bike_light.htm or
http://www.ledshoponline.com/high_power_mr16_led_10deg.htm, the
reality is that even the lower cost MR16 lamps are significantly better
than equivalent wattage halogen lamps, i.e.
http://www.dealextreme.com/p/mr16-3w-cree-q5-180-lumen-white-led-light-bulb-12v-dc-15559.

Frank Krygowski wrote:
On Mar 22, 5:12 pm, James wrote:
Frank Krygowski wrote:
On Mar 22, 1:40 am, James wrote:
There is some, albeit poor, current regulation by most bicycle
alternators, but not voltage regulation as you know.
I'm curious about your claim that current regulation by these things
is poor.
James, why not try some measurements? Both current and voltage, into
(say) either a matched halogen bulb or a power resistor. Give us the
results.
http://www.jim-easterbrook.me.uk/cyc...o_limiter.html

Nice try, but: He didn't give measurements of the current nor the
unclipped voltage vs. road speed, which is what I suggested you
measure. He's assumed certain values of unclipped voltage and
approximately computed the corresponding clipped voltage, based on his
computed generator inductance.

Here are the actual measurements I got, again, using a lab-grade true
RMS meter, with a bog-standard Union bottle generator:

8 mph 10 12 14 16 18 20 22 24 26
mph

5.40 5.80 6.00 6.16 6.30 6.36 6.41 6.45 6.48 6.48 Volts

The general rule of thumb is that halogen bulbs operate best within
10% of their rated voltage.

Here are the current readings we got, in amperes, at those same
speeds:

0.44 0.47 0.49 0.51 0.52 0.52 0.53 0.53 0.53 0.53

From 12 mph to 26 mph, current is constant within a few percent.

Now: Do you own a meter? Why not take some measurements to see if
you match our results? It's really not that hard!

Not personally. I could perhaps borrow one from where I work.

What load did you use?

This was from one dynamo, and may not be representative of the one I
have and prefer to use, or of other Union dynamos.

Jim does say that he assumed the power output at 10mph is 3W, where as
for your results it is only 2.7W.

As Jim actually performed this experiment, and that he says "It is no
wonder that bulbs blow so often." I can only assume he was blowing
globes regularly and decided he needed to do something about it.

JS.

On 3/22/2011 3:52 PM, James wrote:

Whether or not the bicycle dynamo regulation is sufficient to safely run
a halogen headlamp without external regulation, depends on the nominal
rating of the dynamo, the regulation of the dynamo in question, how the
halogen bulb is rating, and the wires used to deliver power too it.

Actually the wires make little difference, since any wire of a heavy
enough gauge not to easily break can carry 500mA.

The problem with bicycle dynamos is that while the current doesn't vary
much, the voltage does. 6V versus 9V at 500mA doesn't matter much to a
good LED lamp, but it matters a lot to an HS3. Hence any decent headlamp
that uses an HS3 bulb will have over-voltage protection built in. That
protection only costs a few cents in terms of components.