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From: Nico Coesel on 3 Apr 2010 16:21
John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote:

>
>ftp://jjlarkin.lmi.net/Curvies_1.jpg
>
>ftp://jjlarkin.lmi.net/Curvies_2.jpg

Wow! I've never seen anything like that. Thanks for sharing!

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico(a)nctdevpuntnl (punt=.)
--------------------------------------------------------------
From: Jim Thompson on 3 Apr 2010 18:37
On Sat, 03 Apr 2010 09:40:57 -0700, John Larkin
<jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote:

>
>ftp://jjlarkin.lmi.net/Curvies_1.jpg
>
>ftp://jjlarkin.lmi.net/Curvies_2.jpg
>
>
>John

California _is_ a twisted kind of place :-)

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

The only thing bipartisan in this country is hypocrisy
From: John Larkin on 3 Apr 2010 19:27
On Sat, 03 Apr 2010 12:25:05 -0700, Archimedes' Lever
<OneBigLever(a)InfiniteSeries.Org> wrote:

>On Sat, 03 Apr 2010 10:49:21 -0700, John Larkin
><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote:
>
>>
>>I'm simulating a digital control loop, essentially a constant-voltage
>>current-limited power supply using an ARM cpu with adc/dac, until the
>>half-day tickets go on sale at Tahoe Donner. $8.
>>
>>John
>
>
> It comes down to the tolerances of the discrete components used to test
>for the voltage set-point in the feedback loop that the adc gets fed
>from, and any components downstream from that, if any prior to the
>output, if you were dumb enough to take the test from other than the
>output taps.

The setpoint is a number in the uP, not a voltage. There are two ADC
inputs, output voltage and output current. Current is sensed with a 15
ohm resistor and scaled up by an opamp and applied to one channel the
uP ADC. The output voltage is picked up by a diffamp and fed to
another ADC channel. The ADC's dac drives the series pass element. All
the control stuff is software. I'm futzing with simulations to get
good dynamics over a range of loads, and to get clean switchover
between constant-current and constant-voltage modes. It's looking like
I can do the whole loop iteration, including calibrations, in under 1
microsecond. Allow another microsecond for protection logic, and I'm
good to go. If I run at 100K hits/second, the ARM can sleep 80% of the
time, which is good since I don't have enough power to run it full
blast.

John

From: John Larkin on 3 Apr 2010 19:27
On Sat, 03 Apr 2010 12:26:08 -0700, Archimedes' Lever
<OneBigLever(a)InfiniteSeries.Org> wrote:

>On Sat, 03 Apr 2010 11:08:26 -0700, hamilton <hamilton(a)nothere.com>
>wrote:
>
>>On 4/3/2010 9:40 AM, John Larkin wrote:
>>>
>>> ftp://jjlarkin.lmi.net/Curvies_1.jpg
>>>
>>> ftp://jjlarkin.lmi.net/Curvies_2.jpg
>>>
>>>
>>> John
>>>
>>LOL, how did you get them to do that ??
>>
>>;-)
>>
>
> It has to be a function of the prevailing wind current at that location
>on the house.


No.

John


From: John Larkin on 3 Apr 2010 19:28
On Sat, 03 Apr 2010 14:48:20 -0500, John O'Flaherty
<quiasmox(a)yeeha.com> wrote:

>On Sat, 03 Apr 2010 11:08:26 -0700, hamilton <hamilton(a)nothere.com>
>wrote:
>
>>On 4/3/2010 9:40 AM, John Larkin wrote:
>>>
>>> ftp://jjlarkin.lmi.net/Curvies_1.jpg
>>>
>>> ftp://jjlarkin.lmi.net/Curvies_2.jpg
>>>
>>>
>>> John
>>>
>>LOL, how did you get them to do that ??
>>
>>;-)
>>
>
>It looks as if the edge of the snow curves down as it slowly slides
>off the roof, and since it never quite melts, it curves right around.

Yes.

John

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