From: David VanHorn <microbrix@gmail.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Fri, 22 May 2020 09:08:01 -0700
Subject: Re: [EE] Light bulb moment (literally)
Thread-Topic: [EE] Light bulb moment (literally)
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That was the coolest bike light, the tube lit up the road wonderfully,
where the bulb was "visible".  The only bad part was the pushbutton starter
for the tube, and if you went a little too slowly the tube would go out
leaving you in the dark and you had to increase speed and start it again.

On Fri, May 22, 2020 at 9:40 AM mike brown <mike@n5qmg.com> wrote:

> I built a prop for an escape room and had to use one of these dynamos to
> power the circuit when the player pedalled a bicycle.  It generated well
> over 36V when pedalled hard.  You should have heard the tantalum capacito=
r
> explode in testing.  Sounded like a rifle going off.
>
> On Fri, May 22, 2020, 10:29 David VanHorn <microbrix@gmail.com> wrote:
>
> > My first bike had a combination bulb and fluorescent light.  6: tube. T=
he
> > generator had the usual 6V output for the bulb and 100V for the tube.
> > Never seen one like that since.  This was around 1967 or 68
> >
> >
> > On Fri, May 22, 2020 at 9:19 AM Chris McSweeny <cpmcsweeny@gmail.com>
> > wrote:
> >
> > > It is, except that the maximum voltage is speed dependent. It is
> (was?) a
> > > common modification to use one to supply 12V across two lights in
> series,
> > > but with a switch to short out one of the lights at lower speeds wher=
e
> > the
> > > dynamo can't supply 12V.
> > >
> > > On Fri, May 22, 2020 at 9:34 AM David C Brown <dcb.home@gmail.com>
> > wrote:
> > >
> > > > I have just realised that the traditional "dynamo" used for bicycle
> > > > lighting (and which is really) a magneto) is, despite being sold as
> a 6
> > > > volt machine,  a actually a constant current device.
> > > > Since both voltage and frequency - hence reactance - rise
> > > > approximately linearly with speed the current remains constant.
> > > > __________________________________________
> > > > David C Brown
> > > > 43 Bings Road
> > > > Whaley Bridge
> > > > High Peak                           Phone: 01663 733236
> > > > Derbyshire                eMail: dcb.home@gmail.com
> > > > SK23 7ND          web: www.bings-knowle.co.uk/dcb
> > > > <http://www.jb.man.ac.uk/~dcb>
> > > >
> > > >
> > > >
> > > > *Sent from my etch-a-sketch*
> > > > --
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