From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.perfora.net (mout.perfora.net [74.208.4.194]) by huchra.bufferbloat.net (Postfix) with ESMTP id BB75E201B52 for ; Wed, 9 May 2012 10:50:13 -0700 (PDT) Received: from [192.168.83.6] (c-76-97-152-51.hsd1.ga.comcast.net [76.97.152.51]) by mrelay.perfora.net (node=mrus3) with ESMTP (Nemesis) id 0MHXLY-1SR4291Zpk-003adF; Wed, 09 May 2012 13:50:11 -0400 Message-ID: <4FAAAE4F.80409@techstarship.com> Date: Wed, 09 May 2012 13:50:07 -0400 From: "Ron Frazier (NTP)" User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.9) Gecko/20100722 Eudora/3.0.4 MIME-Version: 1.0 To: tz References: <02af01cd2daf$05b24bb0$1116e310$@navisys.com.tw> <20120509164726.GA2102@thyrsus.com> In-Reply-To: Content-Type: multipart/alternative; boundary="------------060503090005000704090400" X-Provags-ID: V02:K0:+2JRezEPoBXQPsTRF+5HJKbqtu4MqCLlkL0d9U54Uj6 TzamKBVLdWtM07xP1kAXNyjmonrLYp1TODeIYGS00dlCCp94j3 dffPcZUcNcy0a1fFlk/wzK5TkzesG1rqZGVQy3A0od69VjYumP sU+4Nni9jGwg0TqpSSNb4W5on+iuEpYRuK/KjCtRu2EDzZkt+v JVnj2/7nGTPwbenoJFs5guh1vPaTINIu2eG84Qa5P+pwZDIiuK NEvvt7Ape5oJ5YjQoiBJIhn0xaUrpfbFT/q21FEmUDdFHNWikH 4h6nBJMMhdD8r+wO6cA7CGlJzDJRX/eZ8e2rjUXCeJDb3cNacE e98J7ofpRI1xK9Goh8aT58rss/6DqWJL++x0fJUVh Cc: thumbgps-devel@lists.bufferbloat.net Subject: Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support X-BeenThere: thumbgps-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 09 May 2012 17:50:14 -0000 This is a multi-part message in MIME format. --------------060503090005000704090400 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Hi all, (I'm copying this only to the thumb-gps list and to TZ, the most recent commenter, as I don't know all the parties in the header of TZ's message. You guys can forward it to whomever else may need to see it.) Speaking strictly as a potential user of the thumb-gps device and amateur interested party, I would rather see a supercap, if feasible. I hate the idea of devices having batteries that I have to worry about failing in 5-10 years. I've had the cmos batteries fail in a few computers, sometimes preventing them from booting. It can get really ugly trying to revive them A good high efficiency dc-dc converter chip should allow you to drain all but the last bit of energy from the cap while maintaining whatever working voltage you need. I cannot speak to size issues, as I have never designed a circuit board with one. The GlobalSat BU-353 that I have has a supercap, I believe. Exact backup time is not stated, but I believe it's a few days. Sincerely, Ron On 5/9/2012 1:12 PM, tz wrote: > For a given size (and circuit board footprint) a supercap will have > much less capacity and it has an exponential voltage decay curve, so > it might have plenty of charge but not at a voltage that will hold the > data. This usually means hours, not days of backup. > > A good rechargeable lithium will last several years, maybe longer as > there will be no charge/discharge, maintains voltage until it is > nearly exhausted, and can hold the data for days or weeks. > > On Wed, May 9, 2012 at 12:55 PM, Dave Taht > wrote: > > On Wed, May 9, 2012 at 9:47 AM, Eric S. Raymond > wrote: > > Dave Taht >: > >> What would be the change in cost and delay in manufacturing to > switch to > >> using a supercap, rather than battery? > > > > Why would a supercap be better? > > Effective lifetime of... forever. no need for replacement. insanely > fast recharge. smaller (probably). What's not to like? > > I am not in a huge hurry to get into manufacturing, and I merely > wanted to cost out what what it would do to the bom, any changes to > the PCB, and get an estimate for the time it would take to do. I think > it will bump the unit cost up slightly, > but what price, forever? > > > -- > > Eric S. Raymond > > > > -- > Dave Täht > SKYPE: davetaht > US Tel: 1-239-829-5608 > http://www.bufferbloat.net > _______________________________________________ > Thumbgps-devel mailing list > Thumbgps-devel@lists.bufferbloat.net > > https://lists.bufferbloat.net/listinfo/thumbgps-devel > > > > _______________________________________________ > Thumbgps-devel mailing list > Thumbgps-devel@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/thumbgps-devel > -- (To whom it may concern. My email address has changed. Replying to former messages prior to 03/31/12 with my personal address will go to the wrong address. Please send all personal correspondence to the new address.) (PS - If you email me and don't get a quick response, don't be concerned. I get about 300 emails per day from alternate energy mailing lists and such. I don't always see new messages very quickly. If you need a reply and have not heard from me in 1 - 2 weeks, send your message again.) Ron Frazier timekeepingdude AT techstarship.com --------------060503090005000704090400 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Hi all,

(I'm copying this only to the thumb-gps list and to TZ, the most recent commenter, as I don't know all the parties in the header of TZ's message.  You guys can forward it to whomever else may need to see it.)

Speaking strictly as a potential user of the thumb-gps device and amateur interested party, I would rather see a supercap, if feasible.  I hate the idea of devices having batteries that I have to worry about failing in 5-10 years.  I've had the cmos batteries fail in a few computers, sometimes preventing them from booting.  It can get really ugly trying to revive them  A good high efficiency dc-dc converter chip should allow you to drain all but the last bit of energy from the cap while maintaining whatever working voltage you need.  I cannot speak to size issues, as I have never designed a circuit board with one.  The GlobalSat BU-353 that I have has a supercap, I believe.  Exact backup time is not stated, but I believe it's a few days.

Sincerely,

Ron

On 5/9/2012 1:12 PM, tz wrote:
For a given size (and circuit board footprint) a supercap will have much less capacity and it has an exponential voltage decay curve, so it might have plenty of charge but not at a voltage that will hold the data.  This usually means hours, not days of backup.

A good rechargeable lithium will last several years, maybe longer as there will be no charge/discharge, maintains voltage until it is nearly exhausted, and can hold the data for days or weeks.

On Wed, May 9, 2012 at 12:55 PM, Dave Taht <dave.taht@gmail.com> wrote:
On Wed, May 9, 2012 at 9:47 AM, Eric S. Raymond <esr@thyrsus.com> wrote:
> Dave Taht <dave.taht@gmail.com>:
>> What would be the change in cost and delay in manufacturing to switch to
>> using a supercap, rather than battery?
>
> Why would a supercap be better?

Effective lifetime of... forever. no need for replacement. insanely
fast recharge. smaller (probably). What's not to like?

I am not in a huge hurry to get into manufacturing, and I merely
wanted to cost out what what it would do to the bom, any changes to
the PCB, and get an estimate for the time it would take to do. I think
it will bump the unit cost up slightly,
but what price, forever?

> --
>                <a href="http://www.catb.org/~esr/">Eric S. Raymond</a>



--
Dave Täht
SKYPE: davetaht
US Tel: 1-239-829-5608
http://www.bufferbloat.net
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Thumbgps-devel mailing list
Thumbgps-devel@lists.bufferbloat.net
https://lists.bufferbloat.net/listinfo/thumbgps-devel


_______________________________________________
Thumbgps-devel mailing list
Thumbgps-devel@lists.bufferbloat.net
https://lists.bufferbloat.net/listinfo/thumbgps-devel
  

-- 

(To whom it may concern.  My email address has changed.  Replying to former
messages prior to 03/31/12 with my personal address will go to the wrong
address.  Please send all personal correspondence to the new address.)

(PS - If you email me and don't get a quick response, don't be concerned.
I get about 300 emails per day from alternate energy mailing lists and
such.  I don't always see new messages very quickly.  If you need a
reply and have not heard from me in 1 - 2 weeks, send your message again.)

Ron Frazier
timekeepingdude AT techstarship.com
--------------060503090005000704090400--