On Mon, 05 Dec 2011 17:32:15 -0600, John Fields
wrote:

On Mon, 05 Dec 2011 10:32:35 -0800, John Larkin
wrote:

On Mon, 5 Dec 2011 18:16:30 -0000, "Ian Field"
wrote:


"John Larkin" wrote in message
...
On Sun, 4 Dec 2011 20:54:52 -0000, "Ian Field"
wrote:


"John Larkin" wrote in
message
om...
On Sun, 4 Dec 2011 19:21:21 -0000, "Ian Field"
wrote:


"John Larkin" wrote in
message
news:qndnd7593gkmhghcknui03m42ihpi3hvjk@4ax .com...
On Sun, 04 Dec 2011 09:23:12 -0700, Jim Thompson
wrote:

On Wed, 30 Nov 2011 13:09:54 -0700, Jim Thompson
wrote:

On Sun, 27 Nov 2011 14:56:00 -0000, "Ian Field"
wrote:

Tinkering with the old Sturmey archer bicycle dynamo, I was
wondering
whether it would charge a 1.2Ah SLA any better if the loading was
modified.

The generator is rated 6V/3W, but off load at a decent rate of knots
it
can
produce over a couple of hundred volts.

What I was wondering was whether its possible to get more energy
into
the
battery by letting the generator output voltage stretch its legs so
to
speak
and convert the excessive voltage down with a buck converter.

Can anyone advise on the practicality of this please?

Thanks.


Bwahahahahaha! So this was the original post? Bwahahahahaha!

...Jim Thompson

Perhaps Larkin would be happy to address Ian's question, "What I was
wondering was whether its possible to get more energy into the battery
by letting the generator output voltage stretch its legs so to speak
and convert the excessive voltage down with a buck converter"?


Well its what I wanted to hear anyway, I might start thinking about a
design
for a buck converter to try it out and see what happens, might be
possible
to get away with a MC34063 - failing that maybe a discrete component
design.

Unfortunately my workshop has been dismantled for refurbishing and most
of
the stuff crammed into the shed - so no room to work in there either.

When I tried LTspice I found it a PITA to use - maybe while deprived of
my
workshop I should give it another chance.


I love LT Spice. It's not hard to use, and well worth the short
learning curve.

Here, try this:


Thanks - might download it tomorrow.


I committed a Great Sin on Friday: I *designed* a circuit by fiddling
with Spice. It's a double-terminated LC filter feeding an opamp driver
diffamp, an ADA4950-1, with an offset generator voltage divider, and
all sorts of entangled loadings. Looking at the algebra, I bailed.
Since I'd probably want to sim it to check any computed (and stocked!)
parts values, why not just Spice it and fiddle?

Having noticed quite a few apps on the LT d/l page, I wondered what
switchercad does?


Switchercad is - I think - just another name for LT Spice.

---
Indeed.

Aren't you even beginning to be annoyed by the pilot fish who feeds on
your waste and considers you to be his source of chum?

What a weird, foul old hen you are.

John