OT - ish: Voltage regulator

Kit Wolf said:

Don't see how this is OT - you could ask rec.bicycles.tech but here's
fine.

Quoted message said:

Can anyone direct me to a *simple*, yet effective, voltage regulator
circuit I can use to protect a 6v 2.4w bulb from a SON ?

There are at least 4 solutions:
1) Use a headlamp with a built in zener regulator
2) Use the 2.4W bulb together with an 0.6W rear lamp wired in parallel
3) Use a 3W bulb - these don't require any regulation
4) Buy an LED dynamo lamp.

I'm currently running a B&M lumotec oval 2.4W headlamp from my SON. This
works fine as B&M put a voltage regulator in the headlamp. When the bulb
blows (which I'm using 'cos it came with the lamp), I'll replace it with a
3W bulb and winkle the regulator out with a pair of needlenose pliers.

If you're unsure what the regulator looks like... It's a little
cylindrical component with two wires sticking out either end and it's
wired in parallel with the bulb. If the voltage goes too high, it absorbs
the excess energy and dissipates it as heat, saving your lightbulb. If you
bought your headlamp from SON, it may not have a regulator.

I probably wouldn't reccomend option 2 as LED rear lights are far better.
Also, if you have 2 bulbs (front and back), whenever either one burns out
it's likely to take the other with it.

Quoted message said:

Are any commercial devices available. I have STFW and found links to
Reflectalite but it says not suitable for SONs. No need for recharging
backup batteries.

Cheaper dynamos will burn out bulbs whenever you cycle too fast, but SON
dynamos are very nicely designed and don't need any kind of regulation
whatsoever, so long as they are driving a 3W load. Many modern headlamps
come with zener regulators (as described above) built in. The older lamps
in my junk box generally don't.

It's late, so if any of the above is unclear ask again, and I'll try and
explain better tomorrow.

Kit

I'll give you some context. I have a SON with B&M front and rear lights
on one bike. I also have an damaged 2.4w halogen lamp that was powered
by batteries and a 0.6w bulb tail light. I want to make use of these
lamps with my SON wheel on my fixed, I don't want to splash out on more
B&M lights for a secondary bike that I'll use for once a week or so
only. Plus its a project and will make use of parts that are already
kicking around.

Thanks for you words so far, I like the sound of the SON not needing
regulation.

Kit Wolf said:

Don't see how this is OT - you could ask rec.bicycles.tech but here's
fine.

Quoted message said:

Can anyone direct me to a *simple*, yet effective, voltage regulator
circuit I can use to protect a 6v 2.4w bulb from a SON ?

There are at least 4 solutions:
1) Use a headlamp with a built in zener regulator
2) Use the 2.4W bulb together with an 0.6W rear lamp wired in parallel
3) Use a 3W bulb - these don't require any regulation
4) Buy an LED dynamo lamp.

I'm currently running a B&M lumotec oval 2.4W headlamp from my SON. This
works fine as B&M put a voltage regulator in the headlamp. When the bulb
blows (which I'm using 'cos it came with the lamp), I'll replace it with a
3W bulb and winkle the regulator out with a pair of needlenose pliers.

If you're unsure what the regulator looks like... It's a little
cylindrical component with two wires sticking out either end and it's
wired in parallel with the bulb. If the voltage goes too high, it absorbs
the excess energy and dissipates it as heat, saving your lightbulb. If you
bought your headlamp from SON, it may not have a regulator.

I probably wouldn't reccomend option 2 as LED rear lights are far better.
Also, if you have 2 bulbs (front and back), whenever either one burns out
it's likely to take the other with it.

Quoted message said:

Are any commercial devices available. I have STFW and found links to
Reflectalite but it says not suitable for SONs. No need for recharging
backup batteries.

Cheaper dynamos will burn out bulbs whenever you cycle too fast, but SON
dynamos are very nicely designed and don't need any kind of regulation
whatsoever, so long as they are driving a 3W load. Many modern headlamps
come with zener regulators (as described above) built in. The older lamps
in my junk box generally don't.

It's late, so if any of the above is unclear ask again, and I'll try and
explain better tomorrow.

Kit

How fast is too fast ? I am putting this rig on my fixed and I can't go
very fast on it (don't ask me for numbers, I don't have a speedo on my
fixed)

Kit Wolf said:

Cheaper dynamos will burn out bulbs whenever you cycle too fast, but SON
dynamos are very nicely designed and don't need any kind of regulation
whatsoever, so long as they are driving a 3W load.

Is that so ? How can they run two lamps as a 12v system

MSeries said:

Kit Wolf said:

Cheaper dynamos will burn out bulbs whenever you cycle too fast, but SON
dynamos are very nicely designed and don't need any kind of regulation
whatsoever, so long as they are driving a 3W load.

Is that so ? How can they run two lamps as a 12v system

Fair point. Dynamos are close to being a current source, so it's
actually the resistance of the load that determines the voltage across it.

The sentence should have read "so long as they are driving a load that
works at 500mA" or something like that. Connect two lamps in series, and
the dynamo will "try" to put 500mA through them both for 6W total
output, given enough of whatever the leg equivalent of elbow grease is.

--
Mark.
http://tranchant.plus.com/

Kit Wolf said:

Cheaper dynamos will burn out bulbs whenever you cycle too fast, but
SON dynamos are very nicely designed and don't need any kind of
regulation whatsoever, so long as they are driving a 3W load.

I wonder on which data your statement is based on. Most of the bike
dynamos are remarkably similar in their speed vs. voltage
characteristics with a typical bike light setup. Notable exceptions are
the dynamos with builtin electronics like the Busch&Müller S6 or the
Lightspin. The Schmidt hubs are a bit on the low side at moderate
speeds but catching up at higher ones:
http://www.myra-simon.com/bike/dynotest.html
http://www.enhydralutris.de/Fahrrad/Beleuchtung.pdf.gz (in German)
See also the nice article by Frank Krygowski in Human Power 49:
http://www.ihpva.org/HParchive/PDF/hp49-1999.pdf

Günther

Sounds as if your old lamps should do the trick - just wire them up in
parallel with the dynamo.

Quoted message said:

How fast is too fast ?

It depends on the dynamo, but on the SON speed shouldn't be a problem. I
once did a SPICE simulation of the 20" SON dynamo that suggested the
voltage probably (had to guess some of the parameters) decreases slightly
when you go really fast. So with a SON the bulb may be more likely to burn
out when you're going at a moderate speed - but not so that I'd worry.

I leave my light on all the time, and expect to burn out bulbs every 1000
miles or so.

Quoted message said:

I am putting this rig on my fixed and I can't go
very fast on it (don't ask me for numbers, I don't have a speedo on my
fixed)

Sorry for my 3w thing - Mark's explained the solution. The only problem
with using a 12V setup v. the normal 6V setup is that the light won't turn
on properly until you're riding twice as fast which may not be sensible /
legal.

Kit

MSeries said:

I'll give you some context. I have a SON with B&M front and rear lights
on one bike. I also have an damaged 2.4w halogen lamp that was powered
by batteries and a 0.6w bulb tail light. I want to make use of these
lamps with my SON wheel on my fixed, I don't want to splash out on more
B&M lights for a secondary bike that I'll use for once a week or so
only. Plus its a project and will make use of parts that are already
kicking around.

Thanks for you words so far, I like the sound of the SON not needing
regulation.

With both front & rear bulbs working (3W load) you shouldn't need any
protection, as the SON will effectively self-regulate due to it's current
limit.

The problem comes when one of the bulbs blows - the voltage output of the
SON will then rise (at sufficient speeds), reducing the life of the other
bulb... if the rear blows then the front will take a while to blow; if the
front blows then the rear will follow suit shortly after (due to their
relative powers)

The simple solution? Use a 3W front bulb and a seperate battery-powered
LED rear light. The downside is that 3W bulbs are not that common.

I have a simple but very effective solution on my tourer, though it
requires a fair bit of soldering, based on a load of LEDs wired
series-parallel with the front lamp. I'll send you details if you want.

Nick

--
Email? See my IP address.

ISO-8859-1 Günther Schwarz said:

Kit Wolf said:

Cheaper dynamos will burn out bulbs whenever you cycle too fast, but
SON dynamos are very nicely designed and don't need any kind of
regulation whatsoever, so long as they are driving a 3W load.

I wonder on which data your statement is based on.

As I recall, when I built my wheel, the English instructions that came
with it said that the Schmidt dynamo didn't need any regulation, and that
the Schmidt version of the B&M lamp that I use had the Zener regulator
removed.

The German instructions are online:

http://www.nabendynamo.de/

and on the info page is the phrase:

"Deshalb ist keine leistungsverzehrende Regelungselektronik (Z-Dioden)
erforderlich."

My German's limited, but I think this is saying the same thing (anyone?).

The other data is that I've cycled quite fast (45mph / 72kph) quite
regularly without a regulator and without blowing bulbs. I use a headtorch
as well, in case... I have a newish version of the 20" Schmidt dynamo. I
don't know whether different versions of the dynamo are more/less
well regulated.

Quoted message said:

Most of the bike dynamos are remarkably similar in their speed vs.
voltage characteristics with a typical bike light setup. Notable
exceptions are the dynamos with builtin electronics like the
Busch&Müller S6 or the Lightspin.

On the other hand, going over 55kph with the Lightspin risks burning out
the whole dynamo:

http://www.velovision.co.uk/mag/issue1lightspin.pdf

though this may have been improved for more recent versions:

http://www.ihpva.org/pipermail/trikes/2001q1/007211.html

Quoted message said:

The Schmidt hubs are a bit on the low side at moderate speeds but
catching up at higher ones: http://www.myra-simon.com/bike/dynotest.html
http://www.enhydralutris.de/Fahrrad/Beleuchtung.pdf.gz (in German) See
also the nice article by Frank Krygowski in Human Power 49:
http://www.ihpva.org/HParchive/PDF/hp49-1999.pdf

Frank Krygowski's power v. speed and current v. speed graphs for the 12
ohm load flatten off pretty nicely as far as I can make out (they're a bit
small).

Kit

Kit Wolf said:

The other data is that I've cycled quite fast (45mph / 72kph) quite
regularly without a regulator and without blowing bulbs.

If i go that fast on my fixed on the way home from work, I think blowing
a bulb will be the last of my worries !!!!

Kit Wolf said:

ISO-8859-1 Günther Schwarz said:

Kit Wolf said:

Cheaper dynamos will burn out bulbs whenever you cycle too fast,
but SON dynamos are very nicely designed and don't need any kind of
regulation whatsoever, so long as they are driving a 3W load.

I wonder on which data your statement is based on.

As I recall, when I built my wheel, the English instructions that came
with it said that the Schmidt dynamo didn't need any regulation, and
that the Schmidt version of the B&M lamp that I use had the Zener
regulator removed.

Are you sure that you do not confuse that with the Swiss lightspin
dynamo. For this model it is recommended to remove Zener diodes from
the lights as the dynomo itself is regulated within fractions of a Volt
and the diode in the light just results in additional losses.

Quoted message said:

The German instructions are online:

http://www.nabendynamo.de/

and on the info page is the phrase:

"Deshalb ist keine leistungsverzehrende Regelungselektronik (Z-Dioden)
erforderlich."

Quoted message said:

My German's limited, but I think this is saying the same thing
(anyone?).

| The alternator is of the "claw pole" (not sure about the correct
| translation of "Klauenpolgenerator"😉 type most commonly used in almost
| all bicycle dynamos. [...] When under load a claw pole alternator
| produces a voltage which will not excert a certain maximum value, e.g.
| 7V, even at high speed. Therefor there is need need for power
| consuming electronic regulation (Z diodes).

It does indeed, which surprises me. In fact, Schmidt produces the E6
headlight with it's unique and sophisticated overvoltage protection. It
it not obvious from the text whether they make this statement in
comparison to other alternators e.g. used in car engines which indeed
require a transformer. But they state clearly that their product is not
unique as far as the basic electrical characteristics are concerned.

Quoted message said:

The other data is that I've cycled quite fast (45mph / 72kph) quite
regularly without a regulator and without blowing bulbs. I use a
headtorch as well, in case... I have a newish version of the 20"
Schmidt dynamo. I don't know whether different versions of the dynamo
are more/less well regulated.

As Frank Krygowski explains in the article I cited halogen lamps run
best within a very tight range of voltage. Therefor it is a good idea
to supplement the intrinsic regulation of the alternator with
additional components in the light itself. You might do well without
that, and in many applications it will work OK. A blown bulb is just a
minor mishap after all.

Quoted message said:

Quoted message said:

See also the nice article by Frank Krygowski in Human Power 49:
http://www.ihpva.org/HParchive/PDF/hp49-1999.pdf

Frank Krygowski's power v. speed and current v. speed graphs for the
12 ohm load flatten off pretty nicely as far as I can make out
(they're a bit small).

That was my statement. However, as the curves do not reach zero slope
voltage limiters in the head light are a good idea and work well.

Guenther

ISO-8859-1 Günther Schwarz said:

Kit Wolf said:

ISO-8859-1 Günther Schwarz said:

Kit Wolf wrote:

> Cheaper dynamos will burn out bulbs whenever you cycle too fast,
> but SON dynamos are very nicely designed and don't need any kind of
> regulation whatsoever, so long as they are driving a 3W load.

I wonder on which data your statement is based on.

As I recall, when I built my wheel, the English instructions that came
with it said that the Schmidt dynamo didn't need any regulation, and
that the Schmidt version of the B&M lamp that I use had the Zener
regulator removed.

Are you sure that you do not confuse that with the Swiss lightspin
dynamo. For this model it is recommended to remove Zener diodes from
the lights as the dynomo itself is regulated within fractions of a Volt
and the diode in the light just results in additional losses.

It's possible. There are 'Schmidt' versions of the B&M lamps available
that are advertised as having been adapted for use with the Schmidt
dynohub. I remember this as meaning they had the zener removed, but I
don't remember where I remember this from.

Quoted message said:

Quoted message said:

The German instructions are online:

http://www.nabendynamo.de/

and on the info page is the phrase:

"Deshalb ist keine leistungsverzehrende Regelungselektronik (Z-Dioden)
erforderlich."

Quoted message said:

My German's limited, but I think this is saying the same thing
(anyone?).

| The alternator is of the "claw pole" (not sure about the correct
| translation of "Klauenpolgenerator"😉 type most commonly used in almost
| all bicycle dynamos. [...] When under load a claw pole alternator
| produces a voltage which will not excert a certain maximum value, e.g.
| 7V, even at high speed. Therefor there is need need for power
| consuming electronic regulation (Z diodes).

It does indeed, which surprises me. In fact, Schmidt produces the E6
headlight with it's unique and sophisticated overvoltage protection. It
it not obvious from the text whether they make this statement in
comparison to other alternators e.g. used in car engines which indeed
require a transformer. But they state clearly that their product is not
unique as far as the basic electrical characteristics are concerned.

My turn to be surprised. One thing I note (assuming I understand right) is
that the voltage regulation in the E6 kicks in above 6.8V RMS which would
work out as a 9.6V zener diode - assuming its regulator is an ordinary
zener or equivalent circuit. Frank Krygowski's article says 8V is optimal,
and 7.2V is a value that seems to have stuck in my head from somewhere
else. I wonder whether this regulator has a slightly different purpose -
not regulating the voltage at all under normal circumstances, but perhaps
preventing immediate meltdown if either the front or the rear bulb pops.

Quoted message said:

As Frank Krygowski explains in the article I cited halogen lamps run
best within a very tight range of voltage. Therefor it is a good idea
to supplement the intrinsic regulation of the alternator with
additional components in the light itself. You might do well without
that, and in many applications it will work OK. A blown bulb is just a
minor mishap after all.

IMO LED's are the future - not because they're more efficient than bulbs
but simply because the newer ones are roughly equally efficient whether
they're driven by a moderate current or their maximum current. Unlike
light bulbs where if you drive them at 50% power you don't get much more
than a dull glow. A dynamo for LED lights could be built with much looser
regulation + the idea of having lights that get brighter as you go faster
seems to make sense. I'm also starting to get tired of replacing bulbs -
I figure it costs me 10 to 15 pounds a year. It may be time to buy a
switch.

Quoted message said:

Quoted message said:

Quoted message said:

See also the nice article by Frank Krygowski in Human Power 49:
http://www.ihpva.org/HParchive/PDF/hp49-1999.pdf

Frank Krygowski's power v. speed and current v. speed graphs for the
12 ohm load flatten off pretty nicely as far as I can make out
(they're a bit small).

That was my statement. However, as the curves do not reach zero slope
voltage limiters in the head light are a good idea and work well.

I seem to remember my last lamp got visibly brighter when I took the zener
out - which must reduce the bulb's lifespan, even if it's to the 'normal'
duration.

...Trying to decide whether to take the zener out of my new lamp...
Decisions...

Kit

MSeries said:

Kit Wolf said:

The other data is that I've cycled quite fast (45mph / 72kph) quite
regularly without a regulator and without blowing bulbs.

If i go that fast on my fixed on the way home from work, I think blowing
a bulb will be the last of my worries !!!!

I'd like to see it. Thinking about it, a fixed (narrowish speed range) is
perfectly suited to a dynamo. Perhaps it's a sign that riding a fixed is
the True Way.

Kit

Günther Schwarz said:

Quoted message said:

I wonder whether it could be similar to this circuit, that uses a
low-power zener, power transistor and rectifier bridge to substitute
for a high power zener:

(+)
---------|-------|-----|---
| bridge| _ |
~ | |(-) ^Z C
---------|_______|-| |--B (NPN)
| E
| |
|------|

I will leave that to someone with more expertise in electrical
engineering than I have.

Yes, that would work, but...

Quoted message said:

Quoted message said:

If the front lamp failed you could end up with a 9.6V square wave (for
a 9.6V zener) which would still be too much for the rear lamp.

....remember the square wave voltage will be ~2V higher than the zener
(2x0.7v diode in the bridge plus 0.6v base v in the tranny)6V RMS = 8.5V
peak, so use a 6V8 zener. Remember that you'll be dissipating 2.5W of
power...

Quoted message said:

But the AC voltage will be lower.

The RMS voltage will actually be higher.

I use a different approach: a rear light assembly consisting of
20-something anti-paralleled LEDs - the whole assembly wired *in series*
with the front lamp. Results in a very bright rear lamp and is not
affected by speed, bulbs blowing etc[1].

[1] Unless the front lamp doesn't have zener protection, if so the front
lamp blowing would extinguish the rear.

"Nick." <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I use a different approach: a rear light assembly consisting of
20-something anti-paralleled LEDs - the whole assembly wired *in series*
with the front lamp. Results in a very bright rear lamp and is not
affected by speed, bulbs blowing etc[1].

Wahey! Somebody else at last.

I think you're about the third other person I know who's done this.

cheers,
clive

Kit Wolf said:

Are the resistors power transistors?

Resistors are resistors and transistors are transistors.

SCNR

Guenther