R
rickman
Guest
On 5/19/2017 4:40 PM, default wrote:
You mean they are floating at the surface sleeping?
I seriously doubt they mistake you for another gator. I'm no expert,
but they have lots of other senses than sight. I don't know about
gators where you are, but people have been taken out of kayaks in Africa
by crocs. They are smart enough to know the boat is not edible and go
for the chewy center.
--
Rick C
On Fri, 19 May 2017 12:08:46 -0400, rickman <gnuarm@gmail.com> wrote:
On 5/19/2017 6:55 AM, default wrote:
On Thu, 18 May 2017 08:43:17 -0700, John Larkin
jjlarkin@highlandtechnology.com> wrote:
On Thu, 18 May 2017 07:41:04 -0400, default <default@defaulter.net
wrote:
On 18 May 2017 06:00:58 GMT, Jasen Betts <jasen@xnet.co.nz> wrote:
On 2017-05-13, default <default@defaulter.net> wrote:
On Sat, 13 May 2017 08:35:23 -0700, John Larkin
jjlarkin@highlandtechnology.com> wrote:
On Fri, 12 May 2017 06:47:01 -0400, default <default@defaulter.net
wrote:
On Fri, 12 May 2017 10:47:54 +0200, o pere o <me@somewhere.net> wrote:
On 11/05/17 00:42, Phil Hobbs wrote:
On 05/10/2017 02:31 PM, John Larkin wrote:
On Wed, 10 May 2017 09:57:21 -0700, etpm@whidbey.com wrote:
I have an automatic opening trash can in the kitchen that runs off of
batteries. I wanna run it with a wall wart. When the lid opens it
draws more power than the 750 mA wall wart I tried using to power it
could deliver. This makes sense. I don't want to use a bigger wall
wart and I don't want to have betteries in it all the time to provide
the current. I'm thinking instead of using a capacitor. If the current
and voltage draw as well as the duration to open the lid is measured
can that not be used to calculate the minimum size capacitor? And if
not excessive maybe a cap that would open the lid three or four times
in a row could be used in place of the 6 AA cells it uses now.
Reasonable?
Thanks,
Eric
A conventional cap, no. Maybe a super expensive supercap.
I wouldn't want an electronic trash can. All that cheap, badly
programmed microprocessor/LCD appliance junk will break in a couple of
years, and be annoying meanwhile.
*SIX* AA cells? How long do they last?
A couple of supercaps in series might work fine. For instance,
SCMT22C505MRBA0 AVX CAPACITOR 5F 20% 5V 0.065ohms $5.23000 in onesies
from Digikey.
Two of those in series, with a TL431 across each one (set for 4.8V or
so) to equalize the voltage, plus a charger with about a 50 mA current
limit ought to work, I should think.
Cheers
Phil Hobbs
Is there data on leakage or self-discharge of these beasts? The
datasheet just says "low leakage current" and this could just mean
anything...
Pere
The caps I'm using give the leakage at .16 ma.
http://www.illinoiscapacitor.com/ic_search/super_products_detail.aspx?icpartnumber=700020
50.625 watt hours???!!!
It's magic, or a decimal point slipped 2 places. 1/2 watt I might
believe.
more like 3 decimal places, 0.5*C*V*V/3600
I agree. Did the math and posted as much on 5/14.
I'm thinking they mistakenly used some "one size fits all" or
watt-hours per X farads.
In a related experiment... I'm temporarily using some Maxwell "D-cell"
series caps to power the buoy flasher that got 6 months of use from
3-AA alkaline cells, switching to a solar charged, 175 F, 3 V system
(using caps that cost $15 each). That system is flashing the strobe,
for 8 days on the charge it can get in one day. (cover the solar
cells with aluminum foil and wait till it dies).
So a pair of the $1.29 50 F caps should easily last a day, or perhaps
just use one 50 F and go with 2.5V. (specs on the controller that I'm
using says it works down to 2.2V, and it seems to recover and start
running it's program from the beginning when the voltage gets to about
2V)
The buoy that I'm illuminating belongs to the city.. So I have to keep
the cost low in case they discover that I've modified the buoy and
decide to remove my strobe, or vandals (or Visigoths) make it to that
end of the lake and steal or destroy it...
It's become a "thing" to tweak the buoy with something different each
year. I go kayaking at 3:30 AM to avoid the summer heat, but it's a
challenge to find ways to see where I'm going in the dark on a lake
that's 2 miles long.
Radio beacon? or perhaps a super strobe that I can trigger from 2
miles away?
Tritium light?
Strontium aluminate paint?
Both would be fairly short range visibility. For longer range, why not
use GPS?
Tried that too. Got a Magellan "waterproof" little hand-held thingee.
Cost a small fortune and wasn't waterproof enough to take dunking in
water. Since they stopped the extended warranty plan, I stopped
taking it kayaking. It was hard to read too...
The nice thing about it was when I was on a new creek, I could see my
progress.
They are rated as waterproof, but not very waterproof. I've yet to find
one that will survive on the deck of a kayak for more than a season.
Sooner or later they leak and crap out.
I've never had any trouble seeing where I'm going. Even starlight is
enough to navigate. Once the stars are gone you have to know your
terrain (aquaine?) pretty well though. Overcast makes for interesting
trips though. I take you paddle where there is no illumination from
houses and such? Even a single porch light in the distance can provide
orientation.
Most days (nearly every day) I paddle to the end of the lake and turn
around and come back. There are two large bays jutting off the main
lake and one is nearly as long as the main lake. Add a little fog
(there have been times where I had no idea where I was) and navigation
gets interesting. The houses at the end of the lake make spotting the
buoy difficult for their lights and glare.
It's nice to be able to make a beeline for the buoy, then I'm sure I
cover the same amount of ground each time, and can time my runs.
It isn't a matter of life or death, or even important that I see the
buoy. But I got interested in how to best find it in the dark, and
that's evolved into a fun excuse to tinker with electronics.
Then there's the alligators... It's a big lake and there can only be
4-5 gators in it, but on three occasions I managed to surprise
sleeping gators - against all odds I would think. There's nothing
quite like paddling into a sleeping gator to get one's adrenaline up.
And I may know I'm not part of his food chain, but does he know? And
those things are so near-sighted they just might take me for another
gator impinging on his territory or mate.
You mean they are floating at the surface sleeping?
I seriously doubt they mistake you for another gator. I'm no expert,
but they have lots of other senses than sight. I don't know about
gators where you are, but people have been taken out of kayaks in Africa
by crocs. They are smart enough to know the boat is not edible and go
for the chewy center.
--
Rick C