Bicycle generators and LED lights

This was discussed a while ago in June about my experience with Shake'n'Fake flashlights I got at the Harpers Ferry flea market. They were only about $3 each. There is a little PC board in them, and one of them had a resistor on it, but the wires from the coil were not even connected. Others had the wires twisted together and stuck into a hole on the board, and the "magnet" was just a slug of steel.

I actually replaced the slug with a magnet from an old meter, and I wired up a little circuit with a 1N34 diode, a capacitor, and an LED, to see if any useable voltage would be generated. After I shook it for awhile, I measured the voltage on the capacitor, and sometimes found several hundred millivolts. However, I discovered that it was just coming from the battery through my hand.

The coil was only about 40 turns of fine wire. I wonder how many turns are needed, or how fast the magnet must move, and how strong the magnet needs to be, in order to generate enough voltage and current to light the LED. There are some real ones for sale, but they cost about $20 or so, and I heard that you can actually feel the magnet slowing down as it generates power.

The lights I bought have a clear case, which seems like a cool idea so you can see the mechanism, but actually it produces glare which makes it less effective.

At the same flea market, I bought a couple of hand cranked lights, which seem to work properly, although the mechanism will probably wear out if it is used very much. They were about $5 each. Maybe they could be attached to the handlebars and the counterforce from pedaling could be used to pump a pair of them.

Paul

"Luhan" wrote in news: snipped-for-privacy@p79g2000cwp.googlegroups.com:

THANKS!

--
Jim Yanik
jyanik
at
kua.net

"Luhan" wrote in news: snipped-for-privacy@m73g2000cwd.googlegroups.com:

The shaker I had did not even have the coil connected,the wires were just hid under the lower battery contact,both of them still twisted together. It had a CR2032 and a CR2025 cell in series.The "magnet" was just plain unmagnetized soft iron.

It only cost me $3 at a "dollar" store,no great loss.

--
Jim Yanik
jyanik
at
kua.net

Why bother with the obsolete Sturmey-Archer Dynohub?

Harris Cyclery imports Shimano dynamo hubs that are better in every way than the old Sturmey-Archer: .

The premium quality (and most expensive) dynamo hub is the Schmidt's Original Nabendynamo (SON) hub: .

A wide range of lights, both halogen and LED are available, and many include a standby capacitor so the headlight will remain lit for a couple of minutes when stopped (long enough for most traffic signal to complete a cycle).

-- Tom Sherman - Behind the Cheddar Curtain Impact is not a synonym of affect or effect

"Luhan" wrote in news: snipped-for-privacy@75g2000cwc.googlegroups.com:

Here are a couple of websites that will provide more than you want to know about LED technology.

And while you are at it try looking at

You may be able to find something there that you can use or modify to suit your needs.

Rich

Slightly puzzled with this thread...

Here in Holland (were we cycle a lot!) one can find battery operated headlamps / taillights in enormous numbers in a variety of shops. Cheap too. Which is nice - because my kids seem to incur a lot of wear to their bikes and lighting options mounted thereon. Leds are nice to be visible to other traffic, but if you need to light your own path (dark roads outside town) halogen is a lot better. (less hi-tek then luxeon stars etc, but a *lot* cheaper)

Why bother with dynamo's? Just buy a few sets of NiMH AA's, a cheap

1/10C charger, and you are set for the dark winter. Most lights are quick-removable and serve as hand-torch if needed.

Al in all works a lot better than the conventional slipping dynamo + broken wires / bulbs I had to live with in my youth.

--
 - René

It depends on your needs. I ride brevets which can involve riding literally from dusk till dawn, and there aren't any battery powered lights that will last that long. I'd either have to have multiple lights or carry spare batteries. Rechargeable lights are nice, as long as you are sure you'll have enough time between rides to recharge them. If all I needed was light up to an hour or so once a day, then I'd probably find a battery powered light to be all I needed.

With a generator system, the light is always there, ready to go. You don;t have to think about it at all. Generators and headlamps have improved quite a bit, as well. Hub generators such as the Schmidt SON or the Shimano units are very reliable and have negligible drag. I have the Schmidt on one bike, and a Sanyo Dynapower bottom bracket mounted generator on another. And battery powered lights for a third bike that is used mainly for riding to and from work.

Thank you soooo much. That information on copulation was very helpful....

Luhan

WHAT !!!

Here is some of what shows up at pocketlites.com

Luhan

I guess thats the problem, this site comes up blank for me.

so, I don't get it.

"Luhan" wrote in news:1155433347.812367.211570 @p79g2000cwp.googlegroups.com:

I see I typed pocketLITES.com but I meant pocketLIGHTS.com.

But even the mis-entered "pocketlites.com" link is not a p*rn site.

Your JPEG says pOKEtlites not pOCKtlites, did you typo? Perhaps one or more of the links on the mis-entered pocketlites page was hijacked...

Try this...

I used tiny url to shorten the pocketlights.com link and I tested it. Maybe it will work for you now. Pocketlights.com is a website that sells all kinds of high tech lighting solutions.

Rich

Generator, try the sports section at your local Target.

Michael

In message , dated Sun, 13 Aug 2006, Richard B writes

KinkEEEE!(;-)

--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
2006 is YMMVI- Your mileage may vary immensely.

John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

Anybody tried

? They have led incandescent lamp replacements and available from Digikey.

If the one you are referring to is the Sanyo dynamo, there is a design problem which leads to early falure - that can be fixed...

The operating cam is fixed to its lever by a hex-shaped hole; this hole wears on the matching section of the shaft. It can be fixed by carefuly excising a portion of the aluminium casting and silver-soldering the cam to the shaft. (The excision is required to get access to the shaft/cam with your torch flame.)

Thats just what I typed in for the filename; it could have been anything.

Looks like link to a p*rn site to me.

Luhan

Those flashlights seem way overpriced. I have a couple nice ones that I got for $5 each at the local flea market.

Luhan

So how big is the battery?

--
 JosephKK
 Gegen dummheit kampfen die Gotter Selbst, vergebens.  
  --Schiller