Hello, I recently built-up a front wheel for my bicycle that has a 6v/
3.5w dynamo. These are designed to power headlamps, but I'd prefer to
store the electricity in a battery which could charge my phone. I
believe iPhones charge on standard USB.

My first question is about the battery. Of course, any cell or
chemistry would do, but I'd like to use NiMH AA cells so that I could
easily replace them, and use them in other devices like cameras and
radios while I'm bike-camping. From what I've read, charging NiMH
isn't easy, so I'd prefer to find something off the shelf to use. Is
it possible (or advisable) to use a AA charger as a battery while also
charging the cells? I'm quite in the dark on this topic, and would
appreciate any guidance I can get.

Next, once I have a battery pack that's being charged by my front
wheel, how should I go about charging the iPhone. I will likely use an
off-the-shelf iPhone car charger which are often little more than
cigarette lighter to USB adapters, but these are made for 12v, so I
assume their circuits will be mostly useless to me. What would be
involved in creating a USB outlet on my battery pack?

Once those two fundamental questions are answered I'd like to dream a
little; It'd be most awesome to have a loud speaker built into the
battery pack so that the iPhone could also bump tunes when I'm riding
with friends. Assuming I can somehow re-purpose an OTS iPhone dock, I
should have access to some audio wires, and run them to a volume
dimmer and then to a small speaker. A headlight would be handy too,
but I'm not sure that there will be enough juice for all that. Just
wanted to throw that out there so y'all will know where I'm going.

And just to put minds at ease, I'll use a good sturdy protector case
to house it while it's mounted on the bike. I don't want it to get
hurt in an accident, but it'll be handy to have maps available on my
handlebars.

This is my first serious electronics project, so I'm all ears.

"BikePilgrim" <b...@gmail.com> wrote in message 
news:0...@i72g2000hsd.googlegroups.com...
> Hello, I recently built-up a front wheel for my bicycle that has a 6v/
> 3.5w dynamo. These are designed to power headlamps, but I'd prefer to
> store the electricity in a battery which could charge my phone. I
> believe iPhones charge on standard USB.
>

USB gives 5V, so you can probably just plug the iPhone in (with the right 
cable, of course) to the dynamo itself. The iPhone is almost certainly set 
up to handle higher voltages during charging. If you are worried, you can 
take your car to iPhone charger, and see if it is regulated down to 5V. You 
could also regulate the output of the dynamo down to 5V yourself using a low 
dropout 5V regulator.

> My first question is about the battery. Of course, any cell or
> chemistry would do, but I'd like to use NiMH AA cells so that I could
> easily replace them, and use them in other devices like cameras and
> radios while I'm bike-camping. From what I've read, charging NiMH
> isn't easy, so I'd prefer to find something off the shelf to use. Is
> it possible (or advisable) to use a AA charger as a battery while also
> charging the cells? I'm quite in the dark on this topic, and would
> appreciate any guidance I can get.
>

NiMH cells are pretty easy to charge at low current. Just limit the current 
to 1/10 of the rating of the battery, and you should be fine. They can 
overheat if they get overcharged, leading to shorter life. However, they 
won't burst into flames like a LiION pack. However, why not just use the 
iPhone itself to handle charge management, by plugging the thing directly 
into your dynamo. That way, you can play it while you ride, and it'll charge 
when the voltage is high enough.

> Next, once I have a battery pack that's being charged by my front
> wheel, how should I go about charging the iPhone. I will likely use an
> off-the-shelf iPhone car charger which are often little more than
> cigarette lighter to USB adapters, but these are made for 12v, so I
> assume their circuits will be mostly useless to me. What would be
> involved in creating a USB outlet on my battery pack?
>
> Once those two fundamental questions are answered I'd like to dream a
> little; It'd be most awesome to have a loud speaker built into the
> battery pack so that the iPhone could also bump tunes when I'm riding
> with friends. Assuming I can somehow re-purpose an OTS iPhone dock, I
> should have access to some audio wires, and run them to a volume
> dimmer and then to a small speaker. A headlight would be handy too,
> but I'm not sure that there will be enough juice for all that. Just
> wanted to throw that out there so y'all will know where I'm going.
>

You'll need a battery pack for this one. You can buy batteries that fit into 
a bottle holder. Here is one:

http://www.eatonbikes.com/detail.aspx?ID=190416&Name=Night+Rover%2C+Water+Bottle+Battery%2C+Light

You can build a nice little amplifier for it using an LM384 or something 
like that. Google for LM384 datasheet, and scroll down. There are schematics 
for an amp that would work for you. You could probably just tear the OTS 
iPhone dock apart to get the speakers and plugs.

> And just to put minds at ease, I'll use a good sturdy protector case
> to house it while it's mounted on the bike. I don't want it to get
> hurt in an accident, but it'll be handy to have maps available on my
> handlebars.
>
> This is my first serious electronics project, so I'm all ears. 

Bob Monsen wrote:
> "BikePilgrim" <b...@gmail.com> wrote in message 
> news:0...@i72g2000hsd.googlegroups.com...
> 
>> Hello, I recently built-up a front wheel for my bicycle that has a 6v/
>> 3.5w dynamo. These are designed to power headlamps, but I'd prefer to
>> store the electricity in a battery which could charge my phone. I
>> believe iPhones charge on standard USB.
>>
> 
> USB gives 5V, so you can probably just plug the iPhone in (with the 
> right cable, of course) to the dynamo itself. The iPhone is almost 
> certainly set up to handle higher voltages during charging. If you are 
> worried, you can take your car to iPhone charger, and see if it is 
> regulated down to 5V. You could also regulate the output of the dynamo 
> down to 5V yourself using a low dropout 5V regulator.
> 
>> My first question is about the battery. Of course, any cell or
>> chemistry would do, but I'd like to use NiMH AA cells so that I could
>> easily replace them, and use them in other devices like cameras and
>> radios while I'm bike-camping. From what I've read, charging NiMH
>> isn't easy, so I'd prefer to find something off the shelf to use. Is
>> it possible (or advisable) to use a AA charger as a battery while also
>> charging the cells? I'm quite in the dark on this topic, and would
>> appreciate any guidance I can get.
>>
> 
> NiMH cells are pretty easy to charge at low current. Just limit the 
> current to 1/10 of the rating of the battery, and you should be fine. 
> They can overheat if they get overcharged, leading to shorter life. 
> However, they won't burst into flames like a LiION pack. However, why 
> not just use the iPhone itself to handle charge management, by plugging 
> the thing directly into your dynamo. That way, you can play it while you 
> ride, and it'll charge when the voltage is high enough.
> 
>> Next, once I have a battery pack that's being charged by my front
>> wheel, how should I go about charging the iPhone. I will likely use an
>> off-the-shelf iPhone car charger which are often little more than
>> cigarette lighter to USB adapters, but these are made for 12v, so I
>> assume their circuits will be mostly useless to me. What would be
>> involved in creating a USB outlet on my battery pack?
>>
>> Once those two fundamental questions are answered I'd like to dream a
>> little; It'd be most awesome to have a loud speaker built into the
>> battery pack so that the iPhone could also bump tunes when I'm riding
>> with friends. Assuming I can somehow re-purpose an OTS iPhone dock, I
>> should have access to some audio wires, and run them to a volume
>> dimmer and then to a small speaker. A headlight would be handy too,
>> but I'm not sure that there will be enough juice for all that. Just
>> wanted to throw that out there so y'all will know where I'm going.
>>
> 
> You'll need a battery pack for this one. You can buy batteries that fit 
> into a bottle holder. Here is one:
> 
> http://www.eatonbikes.com/detail.aspx?ID=190416&Name=Night+Rover%2C+Water+Bottle+Battery%2C+Light 
> 
> 
> You can build a nice little amplifier for it using an LM384 or something 
> like that. Google for LM384 datasheet, and scroll down. There are 
> schematics for an amp that would work for you. You could probably just 
> tear the OTS iPhone dock apart to get the speakers and plugs.
> 
>> And just to put minds at ease, I'll use a good sturdy protector case
>> to house it while it's mounted on the bike. I don't want it to get
>> hurt in an accident, but it'll be handy to have maps available on my
>> handlebars.
>>
>> This is my first serious electronics project, so I'm all ears. 
> 
> 
Before you do *anything*, flip the bike over and connect the hub 
'dynamo' to an appropriate bulb. Make sure there is *no* way the bike 
can fall over then spin the wheel fast enough to light the bulb and 
using a multimeter on DC volts, check the voltage from the 'dynamo' 
then repeat on AC Volts.  I strongly suspect that your 'dynamo' is 
actually a permanent magnet alternator and outputs AC!

It would also be worth checking the output at the maximum speed you are 
likely to do with no load on the 'dynamo' (a bike computer to check the 
speed and a drill with a foam sanding drum with no sandpaper on the 
outside of it to drive the wheel by pressing it agents the tyre may be 
some help here).  I wouldn't be surprised to see way over 12V on open 
circuit, downhill conditions.

OTOH maybe Bob is trying to do us all a public service by incinerating 
your phone on the basis that  cyclists operating iPhones while riding 
although a self correcting problem from a Practical Darwinist 
perspective, is likely to result in considerable expense to the rest of 
us in terms of loss of no claims discount and visual clutter consisting 
of tacky roadside 'shrines'.

-- 
Ian Malcolm.   London, ENGLAND.  (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
[at]=@, [dash]=- & [dot]=. *Warning* HTML & >32K emails --> NUL:

"Ian Malcolm" <v...@invalid.invalid> wrote in message 
news:flvbld$p9i$1...@inews.gazeta.pl...
> OTOH maybe Bob is trying to do us all a public service by incinerating 
> your phone on the basis that  cyclists operating iPhones while riding 
> although a self correcting problem from a Practical Darwinist perspective, 
> is likely to result in considerable expense to the rest of us in terms of 
> loss of no claims discount and visual clutter consisting of tacky roadside 
> 'shrines'.
>

You've blown my cover! :)

Thanks, I was assuming DC. Sorry to the OP.

Regards,
 Bob Monsen 

On Mon, 7 Jan 2008 16:36:00 -0800 (PST), BikePilgrim
<b...@gmail.com> wrote:

>Hello, I recently built-up a front wheel for my bicycle that has a 6v/
>3.5w dynamo. These are designed to power headlamps, but I'd prefer to
>store the electricity in a battery which could charge my phone. I
>believe iPhones charge on standard USB.
>
>My first question is about the battery. Of course, any cell or
>chemistry would do, but I'd like to use NiMH AA cells so that I could
>easily replace them, and use them in other devices like cameras and
>radios while I'm bike-camping. From what I've read, charging NiMH
>isn't easy, so I'd prefer to find something off the shelf to use. Is
>it possible (or advisable) to use a AA charger as a battery while also
>charging the cells? I'm quite in the dark on this topic, and would
>appreciate any guidance I can get.
>
>Next, once I have a battery pack that's being charged by my front
>wheel, how should I go about charging the iPhone. I will likely use an
>off-the-shelf iPhone car charger which are often little more than
>cigarette lighter to USB adapters, but these are made for 12v, so I
>assume their circuits will be mostly useless to me. What would be
>involved in creating a USB outlet on my battery pack?
>
>Once those two fundamental questions are answered I'd like to dream a
>little; It'd be most awesome to have a loud speaker built into the
>battery pack so that the iPhone could also bump tunes when I'm riding
>with friends. Assuming I can somehow re-purpose an OTS iPhone dock, I
>should have access to some audio wires, and run them to a volume
>dimmer and then to a small speaker. A headlight would be handy too,
>but I'm not sure that there will be enough juice for all that. Just
>wanted to throw that out there so y'all will know where I'm going.
>
>And just to put minds at ease, I'll use a good sturdy protector case
>to house it while it's mounted on the bike. I don't want it to get
>hurt in an accident, but it'll be handy to have maps available on my
>handlebars.
>
>This is my first serious electronics project, so I'm all ears.

If it were me, I'd start up front with efficiency.  Forget the I phone
car charger since the people that make them may not have efficiency at
heart - after all they have an auto to do the peddling and it has a
300+ watt alternator.

Any watts you devote to toys will have to come out of your legs - you
produce maybe 50-70 watts with sweat.

I think I'd charge a NiMH battery since they are cheap and easy to
deal with and don't explode as easily as lithium.

I'd find the OC voltage of the alternator, and charge a cap to its
full voltage then use a high efficiency buck converter to lower the
voltage for battery charging and perhaps even run the headlight from
the battery pack and put an emergency switch to run the light direct
when the battery is discharged.

"Bump tunes when riding with friends?"  I wouldn't ride with anyone
who takes their music.  Weather radio or walkie talkie, maybe, lights
for the camp, certainly.  You could always get a Winnebago.
-- 

On Jan 7, 4:36=A0pm, BikePilgrim <bikepilg...@gmail.com> wrote:
> Hello, I recently built-up a front wheel for my bicycle that has a 6v/
> 3.5w dynamo. These are designed to power headlamps, but I'd prefer to
> store the electricity in a battery which could charge my phone. I
> believe iPhones charge on standard USB.

Well, most bicycle lights are powered from AC (and my dynamo measured
about 15V with 14 ohms output impedance, but that's variable, the
bicycle speed has a major effect).  Your iPhone wants 5 Vdc, regulated
(i.e. 4.8 to 5.2V allowable range) and with up to 500 mA required.

So, first you have to convert AC (chassis ground) to DC; then
you need to use that DC to effectively charge a battery.  Then you
need to tap regulated power from the battery source (the battery
is a very good filter, much safer to get power after the battery than
upstream straight from the generator).

I did something similar with a voltage doubler rectifier (capacitor/
two
diodes), a lead-acid 6V battery, using the internal impedance of
the dynamo as the only current limit.  Then a low-dropout regulator
set at 5.8V actually ran my headlamp.  The linear regulator was
a power-wasting component, but it didn't waste much (mainly
just kept the AC peaks out of the vulnerable filament).

You'll want to use a switchable 5V regulator of some sort, so it
doesn't
drain the battery when you aren't docked to the iPod.  And you'll
want to verify that the batteries you use (NiMH) can reach 5V
(it'll probably take five or more cells in series).  A standard USB
socket (or a pigtail lead with a USB socket) will connect to
the standard iPod cables for charging.

On 8 jan, 01:36, BikePilgrim <bikepilg...@gmail.com> wrote:
> Hello, I recently built-up a front wheel for my bicycle that has a 6v/
> 3.5w dynamo. These are designed to power headlamps, but I'd prefer to
> store the electricity in a battery which could charge my phone. I
> believe iPhones charge on standard USB.
>
> My first question is about the battery. Of course, any cell or
> chemistry would do, but I'd like to use NiMH AA cells so that I could
> easily replace them, and use them in other devices like cameras and
> radios while I'm bike-camping. From what I've read, charging NiMH
> isn't easy, so I'd prefer to find something off the shelf to use. Is
> it possible (or advisable) to use a AA charger as a battery while also
> charging the cells? I'm quite in the dark on this topic, and would
> appreciate any guidance I can get.
>
> Next, once I have a battery pack that's being charged by my front
> wheel, how should I go about charging the iPhone. I will likely use an
> off-the-shelf iPhone car charger which are often little more than
> cigarette lighter to USB adapters, but these are made for 12v, so I
> assume their circuits will be mostly useless to me. What would be
> involved in creating a USB outlet on my battery pack?
>
> Once those two fundamental questions are answered I'd like to dream a
> little; It'd be most awesome to have a loud speaker built into the
> battery pack so that the iPhone could also bump tunes when I'm riding
> with friends. Assuming I can somehow re-purpose an OTS iPhone dock, I
> should have access to some audio wires, and run them to a volume
> dimmer and then to a small speaker. A headlight would be handy too,
> but I'm not sure that there will be enough juice for all that. Just
> wanted to throw that out there so y'all will know where I'm going.
>
> And just to put minds at ease, I'll use a good sturdy protector case
> to house it while it's mounted on the bike. I don't want it to get
> hurt in an accident, but it'll be handy to have maps available on my
> handlebars.
>
> This is my first serious electronics project, so I'm all ears.

i'm just going to say you : HAPPY NEW YEAR!
And I whish you do a good research on internet  to find that you want.
I must answer to a topic because my electronic teacher ask me to do
it ! And I don't know anything about this topic, consequently i can't
answer !

On Jan 8, 3:21 am, Ian Malcolm
<valid.address.in.signat...@invalid.invalid> wrote:
> Bob Monsen wrote:
> > "BikePilgrim" <bikepilg...@gmail.com> wrote in message
> >news:0...@i72g2000hsd.googlegroups.com...
>
> >> Hello, I recently built-up a front wheel for my bicycle that has a 6v/
> >> 3.5w dynamo. These are designed to power headlamps, but I'd prefer to
> >> store the electricity in a battery which could charge my phone. I
> >> believe iPhones charge on standard USB.
>
> > USB gives 5V, so you can probably just plug the iPhone in (with the
> > right cable, of course) to the dynamo itself. The iPhone is almost
> > certainly set up to handle higher voltages during charging. If you are
> > worried, you can take your car to iPhone charger, and see if it is
> > regulated down to 5V. You could also regulate the output of the dynamo
> > down to 5V yourself using a low dropout 5V regulator.
>
> >> My first question is about the battery. Of course, any cell or
> >> chemistry would do, but I'd like to use NiMH AA cells so that I could
> >> easily replace them, and use them in other devices like cameras and
> >> radios while I'm bike-camping. From what I've read, charging NiMH
> >> isn't easy, so I'd prefer to find something off the shelf to use. Is
> >> it possible (or advisable) to use a AA charger as a battery while also
> >> charging the cells? I'm quite in the dark on this topic, and would
> >> appreciate any guidance I can get.
>
> > NiMH cells are pretty easy to charge at low current. Just limit the
> > current to 1/10 of the rating of the battery, and you should be fine.
> > They can overheat if they get overcharged, leading to shorter life.
> > However, they won't burst into flames like a LiION pack. However, why
> > not just use the iPhone itself to handle charge management, by plugging
> > the thing directly into your dynamo. That way, you can play it while you
> > ride, and it'll charge when the voltage is high enough.
>
> >> Next, once I have a battery pack that's being charged by my front
> >> wheel, how should I go about charging the iPhone. I will likely use an
> >> off-the-shelf iPhone car charger which are often little more than
> >> cigarette lighter to USB adapters, but these are made for 12v, so I
> >> assume their circuits will be mostly useless to me. What would be
> >> involved in creating a USB outlet on my battery pack?
>
> >> Once those two fundamental questions are answered I'd like to dream a
> >> little; It'd be most awesome to have a loud speaker built into the
> >> battery pack so that the iPhone could also bump tunes when I'm riding
> >> with friends. Assuming I can somehow re-purpose an OTS iPhone dock, I
> >> should have access to some audio wires, and run them to a volume
> >> dimmer and then to a small speaker. A headlight would be handy too,
> >> but I'm not sure that there will be enough juice for all that. Just
> >> wanted to throw that out there so y'all will know where I'm going.
>
> > You'll need a battery pack for this one. You can buy batteries that fit
> > into a bottle holder. Here is one:
>
> >http://www.eatonbikes.com/detail.aspx?ID=190416&Name=Night+Rover%2C+W...
>
> > You can build a nice little amplifier for it using an LM384 or something
> > like that. Google for LM384 datasheet, and scroll down. There are
> > schematics for an amp that would work for you. You could probably just
> > tear the OTS iPhone dock apart to get the speakers and plugs.
>
> >> And just to put minds at ease, I'll use a good sturdy protector case
> >> to house it while it's mounted on the bike. I don't want it to get
> >> hurt in an accident, but it'll be handy to have maps available on my
> >> handlebars.
>
> >> This is my first serious electronics project, so I'm all ears.
>
> Before you do *anything*, flip the bike over and connect the hub
> 'dynamo' to an appropriate bulb. Make sure there is *no* way the bike
> can fall over then spin the wheel fast enough to light the bulb and
> using a multimeter on DC volts, check the voltage from the 'dynamo'
> then repeat on AC Volts.  I strongly suspect that your 'dynamo' is
> actually a permanent magnet alternator and outputs AC!
>
> It would also be worth checking the output at the maximum speed you are
> likely to do with no load on the 'dynamo' (a bike computer to check the
> speed and a drill with a foam sanding drum with no sandpaper on the
> outside of it to drive the wheel by pressing it agents the tyre may be
> some help here).  I wouldn't be surprised to see way over 12V on open
> circuit, downhill conditions.
>
> OTOH maybe Bob is trying to do us all a public service by incinerating
> your phone on the basis that  cyclists operating iPhones while riding
> although a self correcting problem from a Practical Darwinist
> perspective, is likely to result in considerable expense to the rest of
> us in terms of loss of no claims discount and visual clutter consisting
> of tacky roadside 'shrines'.
>
> --
> Ian Malcolm.   London, ENGLAND.  (NEWSGROUP REPLY PREFERRED)
> ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
> [at]=@, [dash]=- & [dot]=. *Warning* HTML & >32K emails --> NUL:

are you guys saying that it is totally fine to just go ahead and wire
up a usb cable to a 6v3w dynamo and use it to recharge an iphone?
i have been looking into different projects like this and have not
found definitive answer.

thanks in advance

No, don't do that. The consensus is that your dynamo is probably outputting 
AC, which wouldn't be good for the iPod

Instead, use a 7805 voltage regulator, along with a bridge rectifier and a 
capacitor, like this:
(view with courier font)
                                        ____
                                       |    |
            .-----------o-------o------|7805|---o-------- iPod Vcc
            |           |       |      |____|   |
            |           |       |        |      |
   Shottky  -   Shottky -       |        |      |
            ^           ^       |+       |      |
            |     _     |      ===       |     ---
            |    / \    |      /-\       |     ---
            o---(~ ~)---o       |        |      |
            |    \_/    |       | 2200uF |      | 0.1uF
            |           |       |        |      |
   Shottky  -   Shottky -       |        |      |
            ^           ^       |        |      |
            |           |       |        |      |
            '-----------o-------o--------o------o-------- iPod GND
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)


This will limit the input to 5V, and rectify the circuit. The thing in the 
middle of the bridge is the output from your dynamo.

The diodes are all pointing up (ie, line is at the top). You could use 
Shottky diodes like 1N5817s, or silicon diodes like 1N4001s. The shottky 
diodes will waste less power, and let you get more juice out of the thing. 
You can also get integrated bridge chips, that have 4 terminals, and 
incorporate the 4 diodes. They are generally marked with two terminals that 
have a ~ marking, and two that have + and -, respectively. If you get one of 
these, hook the dynamo to the ~ terminals, and hook the + to the 7805 input, 
and the - to the GND input.

Sorry about the misinformation earlier; I was thinking DC rather than AC. 
Please test this circuit with an ohmmeter before you try it on your iPod...

Regards,
 Bob Monsen

<m...@gmail.com> wrote in message 
news:a...@e25g2000prg.googlegroups.com...
> On Jan 8, 3:21 am, Ian Malcolm
> <valid.address.in.signat...@invalid.invalid> wrote:
>> Bob Monsen wrote:
>> > "BikePilgrim" <bikepilg...@gmail.com> wrote in message
>> >news:0...@i72g2000hsd.googlegroups.com...
>>
>> >> Hello, I recently built-up a front wheel for my bicycle that has a 6v/
>> >> 3.5w dynamo. These are designed to power headlamps, but I'd prefer to
>> >> store the electricity in a battery which could charge my phone. I
>> >> believe iPhones charge on standard USB.
>>
>> > USB gives 5V, so you can probably just plug the iPhone in (with the
>> > right cable, of course) to the dynamo itself. The iPhone is almost
>> > certainly set up to handle higher voltages during charging. If you are
>> > worried, you can take your car to iPhone charger, and see if it is
>> > regulated down to 5V. You could also regulate the output of the dynamo
>> > down to 5V yourself using a low dropout 5V regulator.
>>
>> >> My first question is about the battery. Of course, any cell or
>> >> chemistry would do, but I'd like to use NiMH AA cells so that I could
>> >> easily replace them, and use them in other devices like cameras and
>> >> radios while I'm bike-camping. From what I've read, charging NiMH
>> >> isn't easy, so I'd prefer to find something off the shelf to use. Is
>> >> it possible (or advisable) to use a AA charger as a battery while also
>> >> charging the cells? I'm quite in the dark on this topic, and would
>> >> appreciate any guidance I can get.
>>
>> > NiMH cells are pretty easy to charge at low current. Just limit the
>> > current to 1/10 of the rating of the battery, and you should be fine.
>> > They can overheat if they get overcharged, leading to shorter life.
>> > However, they won't burst into flames like a LiION pack. However, why
>> > not just use the iPhone itself to handle charge management, by plugging
>> > the thing directly into your dynamo. That way, you can play it while 
>> > you
>> > ride, and it'll charge when the voltage is high enough.
>>
>> >> Next, once I have a battery pack that's being charged by my front
>> >> wheel, how should I go about charging the iPhone. I will likely use an
>> >> off-the-shelf iPhone car charger which are often little more than
>> >> cigarette lighter to USB adapters, but these are made for 12v, so I
>> >> assume their circuits will be mostly useless to me. What would be
>> >> involved in creating a USB outlet on my battery pack?
>>
>> >> Once those two fundamental questions are answered I'd like to dream a
>> >> little; It'd be most awesome to have a loud speaker built into the
>> >> battery pack so that the iPhone could also bump tunes when I'm riding
>> >> with friends. Assuming I can somehow re-purpose an OTS iPhone dock, I
>> >> should have access to some audio wires, and run them to a volume
>> >> dimmer and then to a small speaker. A headlight would be handy too,
>> >> but I'm not sure that there will be enough juice for all that. Just
>> >> wanted to throw that out there so y'all will know where I'm going.
>>
>> > You'll need a battery pack for this one. You can buy batteries that fit
>> > into a bottle holder. Here is one:
>>
>> >http://www.eatonbikes.com/detail.aspx?ID=190416&Name=Night+Rover%2C+W...
>>
>> > You can build a nice little amplifier for it using an LM384 or 
>> > something
>> > like that. Google for LM384 datasheet, and scroll down. There are
>> > schematics for an amp that would work for you. You could probably just
>> > tear the OTS iPhone dock apart to get the speakers and plugs.
>>
>> >> And just to put minds at ease, I'll use a good sturdy protector case
>> >> to house it while it's mounted on the bike. I don't want it to get
>> >> hurt in an accident, but it'll be handy to have maps available on my
>> >> handlebars.
>>
>> >> This is my first serious electronics project, so I'm all ears.
>>
>> Before you do *anything*, flip the bike over and connect the hub
>> 'dynamo' to an appropriate bulb. Make sure there is *no* way the bike
>> can fall over then spin the wheel fast enough to light the bulb and
>> using a multimeter on DC volts, check the voltage from the 'dynamo'
>> then repeat on AC Volts.  I strongly suspect that your 'dynamo' is
>> actually a permanent magnet alternator and outputs AC!
>>
>> It would also be worth checking the output at the maximum speed you are
>> likely to do with no load on the 'dynamo' (a bike computer to check the
>> speed and a drill with a foam sanding drum with no sandpaper on the
>> outside of it to drive the wheel by pressing it agents the tyre may be
>> some help here).  I wouldn't be surprised to see way over 12V on open
>> circuit, downhill conditions.
>>
>> OTOH maybe Bob is trying to do us all a public service by incinerating
>> your phone on the basis that  cyclists operating iPhones while riding
>> although a self correcting problem from a Practical Darwinist
>> perspective, is likely to result in considerable expense to the rest of
>> us in terms of loss of no claims discount and visual clutter consisting
>> of tacky roadside 'shrines'.
>>
>> --
>> Ian Malcolm.   London, ENGLAND.  (NEWSGROUP REPLY PREFERRED)
>> ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
>> [at]=@, [dash]=- & [dot]=. *Warning* HTML & >32K emails --> NUL:
>
> are you guys saying that it is totally fine to just go ahead and wire
> up a usb cable to a 6v3w dynamo and use it to recharge an iphone?
> i have been looking into different projects like this and have not
> found definitive answer.
>
> thanks in advance 

On Feb 15, 6:13 am, "Bob Monsen" <rcmon...@gmail.com> wrote:
> No, don't do that. The consensus is that your dynamo is probably outputting
> AC, which wouldn't be good for the iPod
>
> Instead, use a 7805 voltage regulator, along with a bridge rectifier and a
> capacitor, like this:
> (view with courier font)
>                                         ____
>                                        |    |
>             .-----------o-------o------|7805|---o-------- iPod Vcc
>             |           |       |      |____|   |
>             |           |       |        |      |
>    Shottky  -   Shottky -       |        |      |
>             ^           ^       |+       |      |
>             |     _     |      ===       |     ---
>             |    / \    |      /-\       |     ---
>             o---(~ ~)---o       |        |      |
>             |    \_/    |       | 2200uF |      | 0.1uF
>             |           |       |        |      |
>    Shottky  -   Shottky -       |        |      |
>             ^           ^       |        |      |
>             |           |       |        |      |
>             '-----------o-------o--------o------o-------- iPod GND
> (created by AACircuit v1.28.6 beta 04/19/05www.tech-chat.de)
>
> This will limit the input to 5V, and rectify the circuit. The thing in the
> middle of the bridge is the output from your dynamo.
>
> The diodes are all pointing up (ie, line is at the top). You could use
> Shottky diodes like 1N5817s, or silicon diodes like 1N4001s. The shottky
> diodes will waste less power, and let you get more juice out of the thing.
> You can also get integrated bridge chips, that have 4 terminals, and
> incorporate the 4 diodes. They are generally marked with two terminals that
> have a ~ marking, and two that have + and -, respectively. If you get one of
> these, hook the dynamo to the ~ terminals, and hook the + to the 7805 input,
> and the - to the GND input.
>
> Sorry about the misinformation earlier; I was thinking DC rather than AC.
> Please test this circuit with an ohmmeter before you try it on your iPod...
>
> Regards,
>  Bob Monsen
>
> <mikeinter...@gmail.com> wrote in message
>

The hub dynamos are AC and they're constant current sources, not
constant voltage sources.

They will easily deliver 12V RMS at more than about 10kph. The only
reason they cannot legally be used to drive a 12V 6W light on a
bicycle is that there is a minimum speed that the light has to be up
to full brightness. (And I think 6W is too bright for the main light
on a bicycle in the UK which is (or used to be) limited to a maximum
of 3W to prevent dazzling of other road users)

You probably don't want to use a voltage regulator because you'll be
having to output the full 6W or so of power when cycling once the
battery is fully charged just to heat up the voltage regulator.

I've considered a bridge charging a cap and then a DC-DC converter in
order to get a constant voltage source. If the front light blows it
gets very expensive as that often means the end of the front
standlight and rear light. Currently I'm using two zeners to clamp the
voltage to about 9V (based on 6V RMS having a P-P voltage of about 9V
but even with that I've destroyed a front standlight (but the rear
light survived) when the front bulb went.

Tim.