Re: [Phys-l] flashlight : no battery, no bulb

[Bernard Cleyet <bernardcleyet@redshift.com>]

For an old thread, because of time to recover!

I read JD's announcement while in Sue City went immediately to the  
nearest Walgreens and purchased two;  one worked the other didn't.   
Taking advantage of  bargaining learned in Kenya the NO one was half  
price.  A deal for a coil wire ~ 0.0055" and 220 Ohms.  The magnet is  
quite strong.  Much stronger than the typical refrigerator magnet.   
The circuit board has a full wave rectifier and a ~ 0.15 Ohm resistor  
in series w/ the LED.  The batt. is labeled Ni-MH 3.6 V,  40 mAh 14  
h, and 14h 4mA, the latter a useful rating missing from all the  
secondary cells I've previously seen.  And doesn't hold a charge.

bc thanks JD! and imagines oodles of student expts. w/ them

p.s. when I got to Ohio I purchased four more half of which worked.    
I switched one on about two hours ago and it's still going strong".   
When "dead", I'll find how much shaking for how long.  If I were  
paid, I'd use my printer's shaker for a std. shaking.  Curiously the  
output, no load, is, w/ rather vigorous shaking, ten and ~five  
volts.  The asymmetry due, I presume, from the asymmetrically placed  
coil.

On 2008, Jun 02, , at 16:46, John Denker wrote:

> On 06/01/2008 09:44 PM, Marc "Zeke" Kossover wrote:
> > And on the one I bought from them, the so-called capacitors
> > were in fact batteries. The magnet was vaguely magnetic,
> > but the wiring was completely a joke. It didn't really
> > connect to anything.
>
> Thanks for the heads-up ... I wouldn't have discovered the
> problem on my own until much, much later.
>
> This is about as embarrassing as possibly could be.  I gave
> one as a gift to a little kid, then read Marc's note and
> realized I'd been swindled.
>
> Ever try to un-give a present?  Not a good situation.
>
> There *are* products in this category that actually work;
> this just isn't one of them.
>
> Sorry for any confusion I caused.
>
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