On Sun, 4 Dec 2011 19:21:21 -0000, "Ian Field"
wrote:


"John Larkin" wrote in message
.. .
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:


Version 4
SHEET 1 1400 680
WIRE 480 -160 352 -160
WIRE 688 -160 544 -160
WIRE 352 -80 352 -160
WIRE 464 -80 352 -80
WIRE 688 -80 688 -160
WIRE 688 -80 544 -80
WIRE 560 16 496 16
WIRE 688 16 688 -80
WIRE 688 16 640 16
WIRE 832 16 688 16
WIRE 992 16 880 16
WIRE 1072 16 992 16
WIRE 880 32 880 16
WIRE 1072 32 1072 16
WIRE 832 48 832 16
WIRE 496 64 496 16
WIRE 688 64 688 16
WIRE -448 80 -512 80
WIRE -416 80 -448 80
WIRE -304 80 -336 80
WIRE -192 80 -224 80
WIRE 16 80 -48 80
WIRE 80 80 16 80
WIRE 208 80 160 80
WIRE 240 80 208 80
WIRE 448 80 240 80
WIRE 832 96 800 96
WIRE -48 112 -48 80
WIRE -512 128 -512 80
WIRE -192 128 -192 80
WIRE -96 128 -192 128
WIRE 240 128 240 80
WIRE 352 128 352 -80
WIRE 448 128 352 128
WIRE -288 160 -288 128
WIRE -192 160 -192 128
WIRE 352 176 352 128
WIRE 688 176 688 128
WIRE 800 176 800 96
WIRE 880 176 880 112
WIRE 1072 176 1072 112
WIRE 496 192 496 144
WIRE -240 224 -240 128
WIRE -240 224 -304 224
WIRE 240 224 240 192
WIRE -512 256 -512 208
WIRE -304 256 -304 224
WIRE -192 256 -192 224
WIRE -96 256 -96 176
WIRE -48 256 -48 192
WIRE 240 352 240 304
WIRE 352 352 352 256
WIRE -304 368 -304 336
FLAG -512 256 0
FLAG -192 256 0
FLAG -96 256 0
FLAG -48 256 0
FLAG -288 160 0
FLAG -304 368 0
FLAG -448 80 SINE
FLAG 240 352 0
FLAG 208 80 RC
FLAG 496 192 0
FLAG 688 176 0
FLAG 880 176 0
FLAG 1072 176 0
FLAG 800 176 0
FLAG 352 352 0
FLAG 992 16 OUT
FLAG 16 80 DAC
SYMBOL voltage -512 112 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
WINDOW 0 72 33 Left 2
WINDOW 3 42 84 Left 2
SYMATTR InstName V1
SYMATTR Value SINE(0 1 5K)
SYMBOL sw -320 80 R270
WINDOW 0 74 13 VRight 2
WINDOW 3 72 71 VRight 2
SYMATTR InstName S1
SYMATTR Value MYSW
SYMBOL res -320 64 R90
WINDOW 0 -45 60 VBottom 2
WINDOW 3 -38 60 VTop 2
SYMATTR InstName R5
SYMATTR Value 10
SYMBOL cap -208 160 R0
SYMATTR InstName C4
SYMATTR Value 1n
SYMBOL e -48 96 R0
WINDOW 0 38 83 Left 2
WINDOW 3 46 121 Left 2
SYMATTR InstName E2
SYMATTR Value 1
SYMBOL voltage -304 240 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
WINDOW 0 -81 57 Left 2
WINDOW 3 -191 166 Left 2
SYMATTR InstName V2
SYMATTR Value PULSE(-1 1 0 100n 100n 200n 4u 10000)
SYMBOL res 176 64 R90
WINDOW 0 71 56 VBottom 2
WINDOW 3 77 58 VTop 2
SYMATTR InstName R7
SYMATTR Value 1
SYMBOL cap 224 128 R0
SYMATTR InstName C5
SYMATTR Value 1.59e-6
SYMBOL e 496 48 R0
WINDOW 0 47 80 Left 2
WINDOW 3 24 117 Left 2
SYMATTR InstName E4
SYMATTR Value 100000
SYMBOL res 656 0 R90
WINDOW 0 71 56 VBottom 2
WINDOW 3 74 58 VTop 2
SYMATTR InstName R10
SYMATTR Value 1
SYMBOL cap 672 64 R0
WINDOW 0 42 2 Left 2
SYMATTR InstName C8
SYMATTR Value 1.14e-2
SYMBOL e 880 16 R0
WINDOW 0 52 63 Left 2
WINDOW 3 49 102 Left 2
SYMATTR InstName E5
SYMATTR Value 0.2
SYMBOL res 1056 16 R0
WINDOW 0 60 44 Left 2
WINDOW 3 64 78 Left 2
SYMATTR InstName R11
SYMATTR Value 1K
SYMBOL res 336 160 R0
WINDOW 0 54 42 Left 2
WINDOW 3 50 74 Left 2
SYMATTR InstName R8
SYMATTR Value 1K
SYMBOL res 560 -96 R90
WINDOW 0 73 88 VBottom 2
WINDOW 3 47 23 VTop 2
SYMATTR InstName R9
SYMATTR Value 4K
SYMBOL res 224 208 R0
WINDOW 0 -77 42 Left 2
WINDOW 3 -73 80 Left 2
SYMATTR InstName R12
SYMATTR Value 1µ
SYMBOL cap 544 -176 R90
WINDOW 0 -18 77 VBottom 2
WINDOW 3 -44 3 VTop 2
SYMATTR InstName C1
SYMATTR Value 1p
TEXT -480 -176 Left 2 !;ac oct 10 1K 1M
TEXT -480 -224 Left 2 !.tran 0 .001 0 1u
TEXT -536 -64 Left 2 !.model MYSW SW(Ron=1 Roff=1G Vt=.5 Vh=-.4)
TEXT -208 320 Left 2 ;Sample/hold at 250 KHz
TEXT -40 8 Left 2 ;1st Order Lowpass 100 KHz
TEXT 424 336 Left 2 ;Opamp GBW = 1.4M G=100K Corner 14 Hz
TEXT -96 -336 Left 2 ;V545 LVDT MODULE
TEXT -160 -280 Left 2 ;DAC/OUTPUT STAGE SIMULATION
TEXT 480 280 Left 2 ;Gain = 5


Install LT Spice.

Copy the above text into a text editor and save as TEST.ASC.

Double-click on TEST.ASC, or drag it onto the LT Spice shortcut.

You should see the schematic.

Click the "running man" icon to run a time-domain simulation. Then use
the mouse/probe to select points to plot. You can drag little boxes
with the mouse to zoom regions of the waveform, or park on the
waveform and read time and voltage.

Right-click on parts to edit their values.

I used a VCVS and an RC here to simulate an opamp.


Just Friday we were talking about how we tend to use "practical" part
values in sims, as if 1 farad caps were hard to get, or 1 ohm
resistors would get too hot, or 1 pF caps would suffer from
parasitics, or megavolt node voltages would arc over or something.

John