Author Topic: Bike mounted USB Charger  (Read 64603 times)

David Martin

  • Thats Dr Oi You thankyouverymuch
Re: Bike mounted USB Charger
« Reply #50 on: August 14, 2008, 04:50:19 pm »
Having had a spare few minutes today, I started making another charger as above, but in a way that I could start with the really basic circuit and add components to gradually get to the full circuit.

The basic circuit works, but requires a fair turn of speed to get enough output. I think this is because there is hardly any load on the dynamo. The addition of C1 encourages the dynamo to output a little more and also significantly smooths the output ar slower speeds. I think I might go as far as to say C1 is required.

The addition of C2,C3 and R1 produces another significant improvement at lower to medium speeds and should be included if you have space.

If you have the inclination and requirement, the LM2940, C4, C5 can be replaced by (or switched to) a string of power LEDs (up to six LEDs) for a rather impressive headlight. I am currently using three SSC P4 (U bin) LEDs for a 500 lumen output.



Being moderately dense, what would the part numbers for those be? They sound very bright indeed.

I presume one could have a swwitchable headlamp that would let you either charge or illuminate.

..d
"By creating we think. By living we learn" - Patrick Geddes

bobajobrob

Re: Bike mounted USB Charger
« Reply #51 on: August 14, 2008, 04:53:00 pm »
Chaps, where did you find the 2200uF 16v capacitor? I can't find any at maplins.co.uk :(

tiermat

  • According to Jane, I'm a Unisex SpaceAdmin
Re: Bike mounted USB Charger
« Reply #52 on: August 14, 2008, 04:54:20 pm »
RS - Radio Spares

try them

A range of 16V 2200uF caps, from 30p each upto £1.21 each (in packs of 5)
I feel like Captain Kirk, on a brand new planet every day, a little like King Kong on top of the Empire State

Re: Bike mounted USB Charger
« Reply #53 on: August 14, 2008, 06:31:01 pm »
Having had a spare few minutes today, I started making another charger as above, but in a way that I could start with the really basic circuit and add components to gradually get to the full circuit.

The basic circuit works, but requires a fair turn of speed to get enough output. I think this is because there is hardly any load on the dynamo. The addition of C1 encourages the dynamo to output a little more and also significantly smooths the output ar slower speeds. I think I might go as far as to say C1 is required.

The addition of C2,C3 and R1 produces another significant improvement at lower to medium speeds and should be included if you have space.

If you have the inclination and requirement, the LM2940, C4, C5 can be replaced by (or switched to) a string of power LEDs (up to six LEDs) for a rather impressive headlight. I am currently using three SSC P4 (U bin) LEDs for a 500 lumen output.



Being moderately dense, what would the part numbers for those be? They sound very bright indeed.

I presume one could have a swwitchable headlamp that would let you either charge or illuminate.

..d

Indeed - I ran with a switchable output for six months earlier this year (before I changed to yet anothe type of circuit). The LEDs are not available at Maplin, or infact, in the UK . But they are easily avaiable from LED-Shop  by LED-TECH.de (Seoul 3.5W Star LED (P4 Version) by LED-TECH.de) or LEDs Shop by LUMITRONIX® LED-Technik GmbH (LEDs Shop by LUMITRONIX® LED-Technik GmbH)

Of course, you will also need lenses, heatsinking etc.


Re: Bike mounted USB Charger
« Reply #54 on: August 14, 2008, 06:33:02 pm »
Chaps, where did you find the 2200uF 16v capacitor? I can't find any at maplins.co.uk :(

Maplin part VH54J

bobajobrob

Re: Bike mounted USB Charger
« Reply #55 on: August 24, 2008, 01:46:19 am »
Chaps, where did you find the 2200uF 16v capacitor? I can't find any at maplins.co.uk :(

Maplin part VH54J

Thanks Simon.

Here's my second attempt, with the addition of C1 (but not C2, C3 or R1), and the diodes the correct way round this time (!). I can't test it at the moment as I've lost my USB charger cable. If it works then I'll try the all singing, all dancing version next.





Here are all the maplin part numbers (except R1, which I couldn't find), if anyone else wants to try. The price of these bits is £9.54 including postage.

Code: [Select]
LM2940CT                                  AV22Y
D1 - D4     1N5818                        JA47B
C1          2200uF    16v                 VH54J
C2, C3      470uF     63v   Low ESR       DT67X
C4          .47uF     Tantalum bead       WW58N
C5          22uF      Tantalum bead       WW72P
R1          47K       .25W                M47K
USB socket type A                         L51AZ

Re: Bike mounted USB Charger
« Reply #56 on: August 24, 2008, 06:23:54 am »
Here are all the maplin part numbers (except R1, which I couldn't find), if anyone else wants to try.

I would have thought a M47K would do the job, although it is speced at a slightly higher power, I don't think the 15p cost will significantly increase the spend on the project, at least not for a single resistor (there is no reason why you can't use a higher power resistor, they just tend to be bigger than necessary).
Actually, it is rocket science.
 

bobajobrob

Re: Bike mounted USB Charger
« Reply #57 on: August 24, 2008, 02:58:02 pm »
Thanks TimO.

Tried it on an iPod and it shows as charging :thumbsup:

David Martin

  • Thats Dr Oi You thankyouverymuch
Re: Bike mounted USB Charger
« Reply #58 on: August 24, 2008, 07:44:36 pm »
Cool, I have all the bits now. All I need is to try to remmeber which end of a diode is which and the pin out for the USB socket.


..d
"By creating we think. By living we learn" - Patrick Geddes

Re: Bike mounted USB Charger
« Reply #59 on: August 24, 2008, 08:05:05 pm »
... and the pin out for the USB socket.

Wikipedia is probably helpful for that.
Actually, it is rocket science.
 

David Martin

  • Thats Dr Oi You thankyouverymuch
Re: Bike mounted USB Charger
« Reply #60 on: August 24, 2008, 11:29:50 pm »
OK, construction has commenced..

From this:


via this:






to this:



Not yet tested - I will need to fix a flat tyre on a hub gear with coaster brake wheel first

..d
"By creating we think. By living we learn" - Patrick Geddes

bobajobrob

Re: Bike mounted USB Charger
« Reply #61 on: August 25, 2008, 01:38:30 pm »
Looking good :thumbsup:

I haven't tried using one of those boards with the copper strips. It looks like you have to be very careful with the soldering to avoid inadvertently joining two adjacent strips. With my shaky hands I'd probably do just that. They do look neater though.

Re: Bike mounted USB Charger
« Reply #62 on: August 25, 2008, 02:22:55 pm »
With veroboard it's a lot easier than it seems, the copper will tend to attract the solder (at least with good old traditional lead based solder).  The surface tension will keep the solder on the tracks, it's relatively hard to actually get the solder to jump between two tracks.  If it does, it's pretty easy to shift it away.

We mount devices with a much higher pitch, by hand, and so long as you use a very fine tipped soldering iron, and a suitable visual aid, there's no problem
Actually, it is rocket science.
 

David Martin

  • Thats Dr Oi You thankyouverymuch
Re: Bike mounted USB Charger
« Reply #63 on: August 25, 2008, 03:28:51 pm »
It really isn't too hard. As TimO says, the copper tends to keep the solder in one place and it is easy enough to clean the grooves if needed - just run the iron along them.

I might get a chance to try it out this week.

..d
"By creating we think. By living we learn" - Patrick Geddes

bobajobrob

Re: Bike mounted USB Charger
« Reply #64 on: August 26, 2008, 09:52:40 pm »
Righty ho, have ordered some more bits and will give the veroboard a go :thumbsup: Just need to get my head around the component placement.

Re: Bike mounted USB Charger
« Reply #65 on: August 26, 2008, 10:09:19 pm »
Handy hints for vero;

You can cut it with a knive, if you need to break a track (although this may leave a tiny sliver connecting things if you're not careful).  Often people will use the end of a small drill in their hands to clean a holes worth of track away.  You used to be able get a little tool specifically for this purpose.

It's a good idea to clean it before use, ie very lightly rub it down with some fine sandpaper or wire wool, just enough to give it a clean copper look, especially if you've been handling it with your grubby hands, or it's a bit old.  The solder will stick to the clean pink copper much more easily.  Don't rub it down too much though, the copper is pretty thin and you could just remove it entirely!
Actually, it is rocket science.
 

Adam

  • It'll soon be summer
    • Charity ride Durness to Dover 18-25th June 2011
Re: Bike mounted USB Charger
« Reply #66 on: August 27, 2008, 08:50:19 am »
I've been inspired by this thread, and have built my own version, to power my bodged 3W Tesco lights from my Shimano dynamo.

I had previously been using a power supply from Maplins, that I built from a kit, although as that has an adjustable regulator I subsequently found it's not particularly efficient, plus it was only 1A.




I have however replaced the LM2940 with a L78S05CV which is a 2A regulator.  Also, instead of the 4 diodes, I used a W01 bridge rectifier.

It all fits on a copper strip veroboard 5 x 14 holes, so that it all then goes neatly inside a little box, and then I've fitted a switch at the top.
“Life is like riding a bicycle. To keep your balance you must keep moving.” -Albert Einstein

Re: Bike mounted USB Charger
« Reply #67 on: August 27, 2008, 03:38:46 pm »
The problem with the L78SO5CV is that it is not a low dropout regulator - ie it requires the input to be at least 1.2v higher than the output, which in this case means it needs at least 6.2v to work properly - the LM2940 only requires 5.5v. The 2A rating is irrelevant as the dynamo will only produce 500mA.

The bridge rectifier is not as efficient as four Schottky barrier diodes, but will work OK.

Re: Bike mounted USB Charger
« Reply #68 on: August 27, 2008, 06:11:59 pm »
The bridge rectifier is not as efficient as four Schottky barrier diodes, but will work OK.
Not as efficient may be relevant in battery applications, but do you think you'd be able to detect the difference in pedalling effort between that required to generate 500mA at 6.2V and that required to generate 500mA at 5.5V?

border-rider

Re: Bike mounted USB Charger
« Reply #69 on: August 27, 2008, 06:16:30 pm »
The difference may be the low-speed performance - I guess the barrier voltage will give you a low-speed cut-off.  Whether that makes any difference in this case I doubt, but it did on the home-brew LED light system I tried a few years ago.


Re: Bike mounted USB Charger
« Reply #70 on: August 27, 2008, 06:37:09 pm »
Last time I did a home-brew LED light, with just a bridge rectifier (may even have been W01), I could hook it up to the hub and get a flash each time I moved the axle round one notch with my fingers. You can't get much lower speed than that. I agree that the LM2940 is probably different.

Re: Bike mounted USB Charger
« Reply #71 on: August 27, 2008, 07:31:18 pm »
Yes, what MV said.

The FV drop over the Schottky barrier diodes is less than the bridge rectifier. This certainly makes a difference in lighting applications (and that is what I normally use this circuit for). It may not make much difference in the charging application, but in 'series' with the much higher dropout of the L78SO5CV, there may be low speed problems. I don't know this to be the case, but it seems to make theoretical sense.

Adam

  • It'll soon be summer
    • Charity ride Durness to Dover 18-25th June 2011
Re: Bike mounted USB Charger
« Reply #72 on: August 31, 2008, 10:27:42 am »
The main reason I went for the bridge rectifier was to save space on the circuit board, so that it would fit into the small box, making it a very compact design.

Re the low speed issue, it's not a problem in fact.  I get a strobe effect starting at exactly 2 mph, and at 5 mph, the lights are on constantly (or rather, as constantly as the human eye can determine). 

“Life is like riding a bicycle. To keep your balance you must keep moving.” -Albert Einstein

Porkins

  • Formerly Nick H. And a long time ago etc, Eurostar
Re: Bike mounted USB Charger
« Reply #73 on: August 31, 2008, 01:07:45 pm »
What a tantalising thread. I have questions which may sound stupid, but one of these days I hope to pedal off into the wilderness away from mains electricity, but with a camera, small laptop, MP3 player, lights and phone. 

In my ignorance I imagine the perfect setup being something like this:

- a single type of rechargeable battery which can be connected somehow to any of my appliances.  Don't want to lug around 6 different shapes and sizes of batteries

- a fairly big solar panel - say 12" x 8" - which has no protective casing and is hence very light. Attachable to a saddlebag or a pannier.  Maybe a flexible one like this: Power Pocket - flexible solar power in your pocket - imported to the UK by ESC Outdoor

- a wind turbine

- a dynohub

- a gauge to tell me how many amps or whatever I'm getting. (So if the solar panel is doing well I can switch off the turbine and dynohub and go faster)

Is this feasible?

Re: Bike mounted USB Charger
« Reply #74 on: August 31, 2008, 01:36:41 pm »
What a tantalising thread. I have questions which may sound stupid, but one of these days I hope to pedal off into the wilderness away from mains electricity, but with a camera, small laptop, MP3 player, lights and phone. ...

The guage and only using a single battery is just a matter of appropriate electronics, although you may need to custom design some of this, which might be a bit of an issue if you don't do electronics.   

A dynohub is likely to be the most efficient way of generating power.  A bigish solar panel could be useful in a sunny clime (ie not the UK so much!), but I suspect would be better to put out when camping, since it'll be difficult to orientate most efficiently on a bicycle.

A wind turbine would only be sensible if you were cycling into strong wind.  If there is no wind, converting movement into energy is most efficiently done with the dynohub, using your motion to produce wind, and in turn power a wind turbine and generator is guaranteed to be less efficient than a directly driven generator (ie dynohub).

Of course, powering or charging multiple devices could be a bit draining on your power sources.  This will progressively become more realistic as devices become more efficient, although modern devices have already pushed things quite a lot in that direction.

Look up Steve Roberts and his Nomadic Research Labs, for a guy who has been doing a lot of this sort of thing for over a couple of decades.  I think he has changed from bikes (Behemoth) to a ship, since it proved impossible to carry everything he wanted to with a bike!
Actually, it is rocket science.