Dynohub + LED

lance house wrote:

I took the bike out for a ride today with a multimeter attached to it.
At an average cruising speed it outputs 8-12V, but down a light incline
it got up to 14V. Down a big hill I could easily see it topping 20 V,
(Ill check it out next time im near a big hill) so I think I need to
allow for a possibility of putting that much through the LEDs at least
occasionally (although extra cooled by speed, they might also be
operating in hot tropical climates.)

So in otherwords the LEDs will be recieving 0-20V

I would be quite surprised if the voltage goes that high when there is
a load on the output.

I was thinking if linking it to a battery as well so that some power
went to the lights and the excess went to charge a batttery which then
powered the lights when I wasnt moving. I think this is why I thought I
need a rectifier, as mentioned on sheldon browns site.

That sounds complicated. You could get some of the benefits of
batteries by using supercapacitors. A Maxcap LV110505A is rated for
11V and 5 farads. If I understand correctly, this unit stores over
600 watt-seconds of energy at its rated voltage, and should store
about 180 watt-seconds if charged at 6V. That may cause too long an
interval between setting in motion and the lights coming on, but there
are other similar units with smaller capacitance that would charge and
discharge more quickly.

My multimeter only measures up to 200mA and it maxes out on that at
pretty low speeds, so I guess that explains why it blew the last LEDs so
quickly.

I don't know about red LEDs' tolerance for being overdriven, but white
ones are routinely driven at 50mA in commercial flashlight
applications even though their specifications stipulate a nominal
current rating of 20mA and a maximum of 30mA.

I also wouldnt mind hooking up some red LEDs for the back, I guess as
long as I make the string of reds serial and equal to a single white, I
should be able to just run a wire back there.

In my experience, the forward voltage for 5mm white LEDs is almost
exactly twice that for 5mm red LEDs. This rule of thumb does not
apply to Luxeon high flux LEDs.

Incidentally, I tried hooking up a halogen to it and got a depressing
orange glow even at reasonable speeds. It says its a 2.5V 0.5A bulb, so
perhaps the dynohub outputs somewhere between 200-500mA, but if so it
seems that the Amp output is not linear with speed.

There's a clue that the voltage under load will not be as high as you
measured. Unfortunately, it's also a sign that the dynohub may be
unable to put out its rated 3 watts.

Chalo Colina

lance house wrote:

I took the bike out for a ride today with a multimeter attached to it.
At an average cruising speed it outputs 8-12V, but down a light incline
it got up to 14V. Down a big hill I could easily see it topping 20 V,
(Ill check it out next time im near a big hill) so I think I need to
allow for a possibility of putting that much through the LEDs at least
occasionally (although extra cooled by speed, they might also be
operating in hot tropical climates.)

So in otherwords the LEDs will be recieving 0-20V

I would be quite surprised if the voltage goes that high when there is
a load on the output.

I was thinking if linking it to a battery as well so that some power
went to the lights and the excess went to charge a batttery which then
powered the lights when I wasnt moving. I think this is why I thought I
need a rectifier, as mentioned on sheldon browns site.

That sounds complicated. You could get some of the benefits of
batteries by using supercapacitors. A Maxcap LV110505A is rated for
11V and 5 farads. If I understand correctly, this unit stores over
600 watt-seconds of energy at its rated voltage, and should store
about 180 watt-seconds if charged at 6V. That may cause too long an
interval between setting in motion and the lights coming on, but there
are other similar units with smaller capacitance that would charge and
discharge more quickly.

My multimeter only measures up to 200mA and it maxes out on that at
pretty low speeds, so I guess that explains why it blew the last LEDs so
quickly.

I don't know about red LEDs' tolerance for being overdriven, but white
ones are routinely driven at 50mA in commercial flashlight
applications even though their specifications stipulate a nominal
current rating of 20mA and a maximum of 30mA.

I also wouldnt mind hooking up some red LEDs for the back, I guess as
long as I make the string of reds serial and equal to a single white, I
should be able to just run a wire back there.

In my experience, the forward voltage for 5mm white LEDs is almost
exactly twice that for 5mm red LEDs. This rule of thumb does not
apply to Luxeon high flux LEDs.

Incidentally, I tried hooking up a halogen to it and got a depressing
orange glow even at reasonable speeds. It says its a 2.5V 0.5A bulb, so
perhaps the dynohub outputs somewhere between 200-500mA, but if so it
seems that the Amp output is not linear with speed.

There's a clue that the voltage under load will not be as high as you
measured. Unfortunately, it's also a sign that the dynohub may be
unable to put out its rated 3 watts.

Chalo Colina

Chalo wrote:
lance house wrote:

I took the bike out for a ride today with a multimeter attached to it.
At an average cruising speed it outputs 8-12V, but down a light incline
it got up to 14V. Down a big hill I could easily see it topping 20 V,
(Ill check it out next time im near a big hill) so I think I need to
allow for a possibility of putting that much through the LEDs at least
occasionally (although extra cooled by speed, they might also be
operating in hot tropical climates.)

So in otherwords the LEDs will be recieving 0-20V


I would be quite surprised if the voltage goes that high when there is
a load on the output.

It won't, I'm sure. Bike generators are pretty close to constant
current devices. IOW, typical ones put out 0.5 amp, no matter the
resistance - or at least, they try to. The more resistance they see,
the more voltage they develop. I've measured as much as 35 volts off
certain ones in an open circuit condition (IIRC).

But you won't get one to put out more than 0.5 amp (at least, not by
much). And IIRC, the Sturmey-Archer Dynohub put out even less, maybe
0.3 amp instead. I've got the figures stashed somewhere - I'll double
check later.




I was thinking if linking it to a battery as well so that some power
went to the lights and the excess went to charge a batttery which then
powered the lights when I wasnt moving. I think this is why I thought I
need a rectifier, as mentioned on sheldon browns site.


That sounds complicated. You could get some of the benefits of
batteries by using supercapacitors. A Maxcap LV110505A is rated for
11V and 5 farads. If I understand correctly, this unit stores over
600 watt-seconds of energy at its rated voltage, and should store
about 180 watt-seconds if charged at 6V. That may cause too long an
interval between setting in motion and the lights coming on, but there
are other similar units with smaller capacitance that would charge and
discharge more quickly.


My multimeter only measures up to 200mA and it maxes out on that at
pretty low speeds, so I guess that explains why it blew the last LEDs so
quickly.


I don't know about red LEDs' tolerance for being overdriven, but white
ones are routinely driven at 50mA in commercial flashlight
applications even though their specifications stipulate a nominal
current rating of 20mA and a maximum of 30mA.

Here's what I wonder: Since the generator is inherently current
limited, and since LEDs need current limitation, is it possible to just
put the proper number of LEDs in parallel, to share the current properly?

Unfortunately, we're talking about roughly 10 LEDs (i.e. 0.30 amp /
..030mA/LED) ... and since they're diodes, those 10 light during only
half the cycle. You'd want another 10 facing the other way.

Alternately, you could do a diode bridge, using the LEDs themselves as
diodes.

In any case, has anyone tried this idea - just using the inherent
current regulation of a generator to drive LEDs?


Incidentally, I tried hooking up a halogen to it and got a depressing
orange glow even at reasonable speeds. It says its a 2.5V 0.5A bulb, so
perhaps the dynohub outputs somewhere between 200-500mA, but if so it
seems that the Amp output is not linear with speed.

For a dynohub, try http://www.reflectalite.com/lightmodel.html#anchor1
to get a workable bulb. They recommend a GH 105 or 107.

BTW, I haven't tried this, so take it as a citation, not a recommendation!



There's a clue that the voltage under load will not be as high as you
measured. Unfortunately, it's also a sign that the dynohub may be
unable to put out its rated 3 watts.

Again, it's not rated for 3 watts. Modern generators are, but old
Dynohubs weren't.



--
Frank Krygowski [To reply, remove rodent and vegetable dot com.
Substitute cc dot ysu dot
edu]

Chalo wrote:
lance house wrote:

I took the bike out for a ride today with a multimeter attached to it.
At an average cruising speed it outputs 8-12V, but down a light incline
it got up to 14V. Down a big hill I could easily see it topping 20 V,
(Ill check it out next time im near a big hill) so I think I need to
allow for a possibility of putting that much through the LEDs at least
occasionally (although extra cooled by speed, they might also be
operating in hot tropical climates.)

So in otherwords the LEDs will be recieving 0-20V


I would be quite surprised if the voltage goes that high when there is
a load on the output.

It won't, I'm sure. Bike generators are pretty close to constant
current devices. IOW, typical ones put out 0.5 amp, no matter the
resistance - or at least, they try to. The more resistance they see,
the more voltage they develop. I've measured as much as 35 volts off
certain ones in an open circuit condition (IIRC).

But you won't get one to put out more than 0.5 amp (at least, not by
much). And IIRC, the Sturmey-Archer Dynohub put out even less, maybe
0.3 amp instead. I've got the figures stashed somewhere - I'll double
check later.




I was thinking if linking it to a battery as well so that some power
went to the lights and the excess went to charge a batttery which then
powered the lights when I wasnt moving. I think this is why I thought I
need a rectifier, as mentioned on sheldon browns site.


That sounds complicated. You could get some of the benefits of
batteries by using supercapacitors. A Maxcap LV110505A is rated for
11V and 5 farads. If I understand correctly, this unit stores over
600 watt-seconds of energy at its rated voltage, and should store
about 180 watt-seconds if charged at 6V. That may cause too long an
interval between setting in motion and the lights coming on, but there
are other similar units with smaller capacitance that would charge and
discharge more quickly.


My multimeter only measures up to 200mA and it maxes out on that at
pretty low speeds, so I guess that explains why it blew the last LEDs so
quickly.


I don't know about red LEDs' tolerance for being overdriven, but white
ones are routinely driven at 50mA in commercial flashlight
applications even though their specifications stipulate a nominal
current rating of 20mA and a maximum of 30mA.

Here's what I wonder: Since the generator is inherently current
limited, and since LEDs need current limitation, is it possible to just
put the proper number of LEDs in parallel, to share the current properly?

Unfortunately, we're talking about roughly 10 LEDs (i.e. 0.30 amp /
..030mA/LED) ... and since they're diodes, those 10 light during only
half the cycle. You'd want another 10 facing the other way.

Alternately, you could do a diode bridge, using the LEDs themselves as
diodes.

In any case, has anyone tried this idea - just using the inherent
current regulation of a generator to drive LEDs?


Incidentally, I tried hooking up a halogen to it and got a depressing
orange glow even at reasonable speeds. It says its a 2.5V 0.5A bulb, so
perhaps the dynohub outputs somewhere between 200-500mA, but if so it
seems that the Amp output is not linear with speed.

For a dynohub, try http://www.reflectalite.com/lightmodel.html#anchor1
to get a workable bulb. They recommend a GH 105 or 107.

BTW, I haven't tried this, so take it as a citation, not a recommendation!



There's a clue that the voltage under load will not be as high as you
measured. Unfortunately, it's also a sign that the dynohub may be
unable to put out its rated 3 watts.

Again, it's not rated for 3 watts. Modern generators are, but old
Dynohubs weren't.



--
Frank Krygowski [To reply, remove rodent and vegetable dot com.
Substitute cc dot ysu dot
edu]

Chalo wrote:
lance house wrote:

I took the bike out for a ride today with a multimeter attached to it.
At an average cruising speed it outputs 8-12V, but down a light incline
it got up to 14V. Down a big hill I could easily see it topping 20 V,
(Ill check it out next time im near a big hill) so I think I need to
allow for a possibility of putting that much through the LEDs at least
occasionally (although extra cooled by speed, they might also be
operating in hot tropical climates.)

So in otherwords the LEDs will be recieving 0-20V


I would be quite surprised if the voltage goes that high when there is
a load on the output.

It won't, I'm sure. Bike generators are pretty close to constant
current devices. IOW, typical ones put out 0.5 amp, no matter the
resistance - or at least, they try to. The more resistance they see,
the more voltage they develop. I've measured as much as 35 volts off
certain ones in an open circuit condition (IIRC).

But you won't get one to put out more than 0.5 amp (at least, not by
much). And IIRC, the Sturmey-Archer Dynohub put out even less, maybe
0.3 amp instead. I've got the figures stashed somewhere - I'll double
check later.




I was thinking if linking it to a battery as well so that some power
went to the lights and the excess went to charge a batttery which then
powered the lights when I wasnt moving. I think this is why I thought I
need a rectifier, as mentioned on sheldon browns site.


That sounds complicated. You could get some of the benefits of
batteries by using supercapacitors. A Maxcap LV110505A is rated for
11V and 5 farads. If I understand correctly, this unit stores over
600 watt-seconds of energy at its rated voltage, and should store
about 180 watt-seconds if charged at 6V. That may cause too long an
interval between setting in motion and the lights coming on, but there
are other similar units with smaller capacitance that would charge and
discharge more quickly.


My multimeter only measures up to 200mA and it maxes out on that at
pretty low speeds, so I guess that explains why it blew the last LEDs so
quickly.


I don't know about red LEDs' tolerance for being overdriven, but white
ones are routinely driven at 50mA in commercial flashlight
applications even though their specifications stipulate a nominal
current rating of 20mA and a maximum of 30mA.

Here's what I wonder: Since the generator is inherently current
limited, and since LEDs need current limitation, is it possible to just
put the proper number of LEDs in parallel, to share the current properly?

Unfortunately, we're talking about roughly 10 LEDs (i.e. 0.30 amp /
..030mA/LED) ... and since they're diodes, those 10 light during only
half the cycle. You'd want another 10 facing the other way.

Alternately, you could do a diode bridge, using the LEDs themselves as
diodes.

In any case, has anyone tried this idea - just using the inherent
current regulation of a generator to drive LEDs?


Incidentally, I tried hooking up a halogen to it and got a depressing
orange glow even at reasonable speeds. It says its a 2.5V 0.5A bulb, so
perhaps the dynohub outputs somewhere between 200-500mA, but if so it
seems that the Amp output is not linear with speed.

For a dynohub, try http://www.reflectalite.com/lightmodel.html#anchor1
to get a workable bulb. They recommend a GH 105 or 107.

BTW, I haven't tried this, so take it as a citation, not a recommendation!



There's a clue that the voltage under load will not be as high as you
measured. Unfortunately, it's also a sign that the dynohub may be
unable to put out its rated 3 watts.

Again, it's not rated for 3 watts. Modern generators are, but old
Dynohubs weren't.



--
Frank Krygowski [To reply, remove rodent and vegetable dot com.
Substitute cc dot ysu dot
edu]

Frank Krygowski writes:

Chalo wrote:
lance house wrote:

I took the bike out for a ride today with a multimeter attached to
it. At an average cruising speed it outputs 8-12V, but down a light
incline it got up to 14V. Down a big hill I could easily see it
topping 20 V, (Ill check it out next time im near a big hill) so I
think I need to allow for a possibility of putting that much
through the LEDs at least occasionally (although extra cooled by
speed, they might also be operating in hot tropical climates.)

So in otherwords the LEDs will be recieving 0-20V
I would be quite surprised if the voltage goes that high when there
is
a load on the output.

It won't, I'm sure. Bike generators are pretty close to constant
current devices. IOW, typical ones put out 0.5 amp, no matter the
resistance - or at least, they try to. The more resistance they see,
the more voltage they develop. I've measured as much as 35 volts off
certain ones in an open circuit condition (IIRC).

But you won't get one to put out more than 0.5 amp (at least, not by
much). And IIRC, the Sturmey-Archer Dynohub put out even less, maybe
0.3 amp instead. I've got the figures stashed somewhere - I'll double
check later.



I was thinking if linking it to a battery as well so that some
power went to the lights and the excess went to charge a batttery
which then powered the lights when I wasnt moving. I think this is
why I thought I need a rectifier, as mentioned on sheldon browns
site.
That sounds complicated. You could get some of the benefits of
batteries by using supercapacitors. A Maxcap LV110505A is rated for
11V and 5 farads. If I understand correctly, this unit stores over
600 watt-seconds of energy at its rated voltage, and should store
about 180 watt-seconds if charged at 6V. That may cause too long an
interval between setting in motion and the lights coming on, but there
are other similar units with smaller capacitance that would charge and
discharge more quickly.

My multimeter only measures up to 200mA and it maxes out on that at
pretty low speeds, so I guess that explains why it blew the last
LEDs so quickly.
I don't know about red LEDs' tolerance for being overdriven, but
white
ones are routinely driven at 50mA in commercial flashlight
applications even though their specifications stipulate a nominal
current rating of 20mA and a maximum of 30mA.

Here's what I wonder: Since the generator is inherently current
limited, and since LEDs need current limitation, is it possible to
just put the proper number of LEDs in parallel, to share the current
properly?

Putting diodes in parallel is generally considered a bad idea because
chances are very good that they will have different voltage drops and
not share the current equally. One can get around this a bit by
putting an equalizing resistor in series with each diode.

Unfortunately, we're talking about roughly 10 LEDs (i.e. 0.30 amp /
.030mA/LED) ... and since they're diodes, those 10 light during only
half the cycle. You'd want another 10 facing the other way.

Alternately, you could do a diode bridge, using the LEDs themselves as
diodes.

There is no current in a bridge without a load. Might as well connect
an anti-parallel pair. Nothing wrong with that.

Frank Krygowski writes:

Chalo wrote:
lance house wrote:

I took the bike out for a ride today with a multimeter attached to
it. At an average cruising speed it outputs 8-12V, but down a light
incline it got up to 14V. Down a big hill I could easily see it
topping 20 V, (Ill check it out next time im near a big hill) so I
think I need to allow for a possibility of putting that much
through the LEDs at least occasionally (although extra cooled by
speed, they might also be operating in hot tropical climates.)

So in otherwords the LEDs will be recieving 0-20V
I would be quite surprised if the voltage goes that high when there
is
a load on the output.

It won't, I'm sure. Bike generators are pretty close to constant
current devices. IOW, typical ones put out 0.5 amp, no matter the
resistance - or at least, they try to. The more resistance they see,
the more voltage they develop. I've measured as much as 35 volts off
certain ones in an open circuit condition (IIRC).

But you won't get one to put out more than 0.5 amp (at least, not by
much). And IIRC, the Sturmey-Archer Dynohub put out even less, maybe
0.3 amp instead. I've got the figures stashed somewhere - I'll double
check later.



I was thinking if linking it to a battery as well so that some
power went to the lights and the excess went to charge a batttery
which then powered the lights when I wasnt moving. I think this is
why I thought I need a rectifier, as mentioned on sheldon browns
site.
That sounds complicated. You could get some of the benefits of
batteries by using supercapacitors. A Maxcap LV110505A is rated for
11V and 5 farads. If I understand correctly, this unit stores over
600 watt-seconds of energy at its rated voltage, and should store
about 180 watt-seconds if charged at 6V. That may cause too long an
interval between setting in motion and the lights coming on, but there
are other similar units with smaller capacitance that would charge and
discharge more quickly.

My multimeter only measures up to 200mA and it maxes out on that at
pretty low speeds, so I guess that explains why it blew the last
LEDs so quickly.
I don't know about red LEDs' tolerance for being overdriven, but
white
ones are routinely driven at 50mA in commercial flashlight
applications even though their specifications stipulate a nominal
current rating of 20mA and a maximum of 30mA.

Here's what I wonder: Since the generator is inherently current
limited, and since LEDs need current limitation, is it possible to
just put the proper number of LEDs in parallel, to share the current
properly?

Putting diodes in parallel is generally considered a bad idea because
chances are very good that they will have different voltage drops and
not share the current equally. One can get around this a bit by
putting an equalizing resistor in series with each diode.

Unfortunately, we're talking about roughly 10 LEDs (i.e. 0.30 amp /
.030mA/LED) ... and since they're diodes, those 10 light during only
half the cycle. You'd want another 10 facing the other way.

Alternately, you could do a diode bridge, using the LEDs themselves as
diodes.

There is no current in a bridge without a load. Might as well connect
an anti-parallel pair. Nothing wrong with that.

Frank Krygowski writes:

Chalo wrote:
lance house wrote:

I took the bike out for a ride today with a multimeter attached to
it. At an average cruising speed it outputs 8-12V, but down a light
incline it got up to 14V. Down a big hill I could easily see it
topping 20 V, (Ill check it out next time im near a big hill) so I
think I need to allow for a possibility of putting that much
through the LEDs at least occasionally (although extra cooled by
speed, they might also be operating in hot tropical climates.)

So in otherwords the LEDs will be recieving 0-20V
I would be quite surprised if the voltage goes that high when there
is
a load on the output.

It won't, I'm sure. Bike generators are pretty close to constant
current devices. IOW, typical ones put out 0.5 amp, no matter the
resistance - or at least, they try to. The more resistance they see,
the more voltage they develop. I've measured as much as 35 volts off
certain ones in an open circuit condition (IIRC).

But you won't get one to put out more than 0.5 amp (at least, not by
much). And IIRC, the Sturmey-Archer Dynohub put out even less, maybe
0.3 amp instead. I've got the figures stashed somewhere - I'll double
check later.



I was thinking if linking it to a battery as well so that some
power went to the lights and the excess went to charge a batttery
which then powered the lights when I wasnt moving. I think this is
why I thought I need a rectifier, as mentioned on sheldon browns
site.
That sounds complicated. You could get some of the benefits of
batteries by using supercapacitors. A Maxcap LV110505A is rated for
11V and 5 farads. If I understand correctly, this unit stores over
600 watt-seconds of energy at its rated voltage, and should store
about 180 watt-seconds if charged at 6V. That may cause too long an
interval between setting in motion and the lights coming on, but there
are other similar units with smaller capacitance that would charge and
discharge more quickly.

My multimeter only measures up to 200mA and it maxes out on that at
pretty low speeds, so I guess that explains why it blew the last
LEDs so quickly.
I don't know about red LEDs' tolerance for being overdriven, but
white
ones are routinely driven at 50mA in commercial flashlight
applications even though their specifications stipulate a nominal
current rating of 20mA and a maximum of 30mA.

Here's what I wonder: Since the generator is inherently current
limited, and since LEDs need current limitation, is it possible to
just put the proper number of LEDs in parallel, to share the current
properly?

Putting diodes in parallel is generally considered a bad idea because
chances are very good that they will have different voltage drops and
not share the current equally. One can get around this a bit by
putting an equalizing resistor in series with each diode.

Unfortunately, we're talking about roughly 10 LEDs (i.e. 0.30 amp /
.030mA/LED) ... and since they're diodes, those 10 light during only
half the cycle. You'd want another 10 facing the other way.

Alternately, you could do a diode bridge, using the LEDs themselves as
diodes.

There is no current in a bridge without a load. Might as well connect
an anti-parallel pair. Nothing wrong with that.

Jim Smith wrote:

Frank Krygowski writes:


Here's what I wonder: Since the generator is inherently current
limited, and since LEDs need current limitation, is it possible to
just put the proper number of LEDs in parallel, to share the current
properly?


Putting diodes in parallel is generally considered a bad idea because
chances are very good that they will have different voltage drops and
not share the current equally. One can get around this a bit by
putting an equalizing resistor in series with each diode.

Hmmm. (Thinking slowly, since I'm an ME, not an EE) OK, that makes
some sense to me. But are the differences likely to be significant?
Another post referred to LED flashlights significantly overdriving the
LEDs. If you were closer to spec by my method, would the (apparent)
safety factor in the ratings be good enough?

A problem, I guess, is that failure might be quickly progressive. One
LED might fail and take out the whole array.

But I think of resistors as energy losers. Also, each resistor is
another circuit element to try to fit into the package. Would it be
better to use the standard trick of opposed Zeners to limit voltage?
Could the internal resistance of the generator then be all you'd need in
the circuit?

(I never wanted to know more about EE until I started playing with
generators!)



Unfortunately, we're talking about roughly 10 LEDs (i.e. 0.30 amp /
.030mA/LED) ... and since they're diodes, those 10 light during only
half the cycle. You'd want another 10 facing the other way.

Alternately, you could do a diode bridge, using the LEDs themselves as
diodes.


There is no current in a bridge without a load. Might as well connect
an anti-parallel pair. Nothing wrong with that.

My idea of an LED bridge was to possibly reduce the LED count compared
to 10 facing East, plus 10 facing West. The load would be the rest of
the LEDs. I think.



--
--------------------+
Frank Krygowski [To reply, remove rodent and vegetable dot com,
replace with cc.ysu dot edu]

Jim Smith wrote:

Frank Krygowski writes:


Here's what I wonder: Since the generator is inherently current
limited, and since LEDs need current limitation, is it possible to
just put the proper number of LEDs in parallel, to share the current
properly?


Putting diodes in parallel is generally considered a bad idea because
chances are very good that they will have different voltage drops and
not share the current equally. One can get around this a bit by
putting an equalizing resistor in series with each diode.

Hmmm. (Thinking slowly, since I'm an ME, not an EE) OK, that makes
some sense to me. But are the differences likely to be significant?
Another post referred to LED flashlights significantly overdriving the
LEDs. If you were closer to spec by my method, would the (apparent)
safety factor in the ratings be good enough?

A problem, I guess, is that failure might be quickly progressive. One
LED might fail and take out the whole array.

But I think of resistors as energy losers. Also, each resistor is
another circuit element to try to fit into the package. Would it be
better to use the standard trick of opposed Zeners to limit voltage?
Could the internal resistance of the generator then be all you'd need in
the circuit?

(I never wanted to know more about EE until I started playing with
generators!)



Unfortunately, we're talking about roughly 10 LEDs (i.e. 0.30 amp /
.030mA/LED) ... and since they're diodes, those 10 light during only
half the cycle. You'd want another 10 facing the other way.

Alternately, you could do a diode bridge, using the LEDs themselves as
diodes.


There is no current in a bridge without a load. Might as well connect
an anti-parallel pair. Nothing wrong with that.

My idea of an LED bridge was to possibly reduce the LED count compared
to 10 facing East, plus 10 facing West. The load would be the rest of
the LEDs. I think.



--
--------------------+
Frank Krygowski [To reply, remove rodent and vegetable dot com,
replace with cc.ysu dot edu]