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Stephen R Phillips | 1 Mar 01:05
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Re: [EE] Spring Contacts for devices Off the shelf or what?


--- msi1259 <msi1259 <at> rogers.com> wrote:

> Stephen R Phillips wrote:
> > <snip> the device requires case contacts AND also require contacts
> for
> > charging the unit. It will be operated in a dirty and dusty
> environment
> > therefore the contacts need to somehow be self cleaning etc. <snip>
> In medical applications (ultrasound probes, MRI coils), I see a lot
> of 
> Hypertronics connectors used.( http://www.hypertronics.com/ ). Was
> also 
> looking at the connectors on an wheel alignment machine while my car
> was 
> being serviced - the alignment heads plugged into a  connector with a
> 
> small hinged cap and what looked sort of like a oiled felt pad that 
> moved down the contact pins as the female pressed in. Mini USB 
> connectors seem to stand a fair bit of abuse (mp3 players, camera,
> phones).
I'll have a look maybe they can make custom (at least they have contact
expertise and mention custom as a possibility).

Stephen

Stephen R. Phillips was here
Please be advised what was said may be absolutely wrong, and hereby this disclaimer follows.  I reserve the
right to be wrong and admit it in front of the entire world.
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Matthew Miller | 1 Mar 01:18

[EE[ Favorite R-R Opamp?

Hi Everyone,

Since beginning work with op-amps, I've found rail-to-rail op-amps very
useful for battery powered applications. I bet you folks have a favorite in
this area, but what brand op-amps have the lowest cost?

I've recently tried the Microchip op-amps and they are pretty good. For some
of them the offset voltages are awful though, but there not too bad,
considering the cost.

Can anyone recommend a line of good rail-to-rail, single supply op-amps? I'm
asking here since the Digikey catalog has become too think to thumb
through. (If my postman wasn't such a nice guy he would hate me for
receiving Digikey catalogs...)

Thanks. :)

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Dario Greggio | 1 Mar 01:36
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Re: [EE[ Favorite R-R Opamp?

Matthew Miller wrote:

> Can anyone recommend a line of good rail-to-rail, single supply op-amps? I'm
> asking here since the Digikey catalog has become too think to thumb
> through. (If my postman wasn't such a nice guy he would hate me for
> receiving Digikey catalogs...)

I used to use TLC083 from TI.

But am moving to Microchip as well :)

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Bob Blick | 1 Mar 01:55
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Re: [EE[ Favorite R-R Opamp?

--- Matthew Miller <namiller2 <at> naxs.net> wrote:
> Since beginning work with op-amps, I've found
> rail-to-rail op-amps very
> useful for battery powered applications. I bet you
> folks have a favorite in
> this area, but what brand op-amps have the lowest
> cost?

Rail to rail input, output, or both? There are very
few opamps with rail-to-rail inputs, LMC6482 is one(a
dual).

It's actually surprising what a good part it is,
fairly accurate, fairly fast, stable, and rail-to-rail
in and out. Some crossover offset on the input because
of the unusual(wonderfully so) input stage, but not
large.

Cheerful regards,

Bob
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James Newton | 1 Mar 02:00

RE: [OT] Just wondering..

Byron Jeff Sent: Friday, February 29, 2008 15:24
> 1) At the efficiency levels that solar converts to electricity, it takes 
> more energy to create solar panels than they produce.

Ahhh... Huh? Could you provide a reference or supporting data for that
assertion? If it takes more energy to make a solar panel than it will ever
produce, wouldn't the cost of the panel exceed the value of the electricity
produced? Why would anyone produce a panel if that were the case? Wouldn't
the power to make it cost them more than the panel is worth?

http://techref.massmind.org/techref/other/solar/case1.htm my solar panels
cost $16,000. The system cost $21,000 TOTAL including professional
installation. I paid $12,759 after rebates. The first year, it made $1,400
worth of electricity. The panels are warranted for 25 years so they should
produce $29,400 dollars worth of electricity. And that assumes that the
price of electricity stays the same; which it has not:
http://techref.massmind.org/images/other/ePwrRates.GIF

> 2) Solar panels have nasty stuff in them too. They cause issues in both
> production and waste.

Pretty much everything has nasty stuff in it, but I would curious to know
exactly what they have that is any worse than roofing material.

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James. 

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Herbert Graf | 1 Mar 02:02

Re: [EE]: I am looking for a small positive displacement fan


On Sat, 2008-03-01 at 11:25 +1300, Roy wrote:
> You could use heated air from the manifold when the engine is running to 
> the save energy otherwise used to heat the air while the engine is running.

Unfortunately when it's cold it can take a surprising amount of time for
an idling engine to get anywhere near warm enough to put a dent on
defrosting a windsheild. Trust me, I know, it was -25C (about -13F) last
night here...

TTYL
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Apptech | 1 Mar 02:03
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Re: [OT] Just wondering..

BCC recipients:

            Stop reading when eyes glaze over ...

______________

> 1) At the efficiency levels that solar converts to 
> electricity, it takes
> more energy to create solar panels than they produce.

1. Reference?
2. Credible reference?
3. Peer reviewed credible reference?
4. Peer reviewed accurate credible reference? :-)

Modern solar panels have efficiencies of 13% - 15% for 
single junction cells and around 30% for triple junction 
cells in space applications where a wider spectrum is 
available and used. Lifetimes for reasonable quality 
terrestrial panels are a genuine 20 years wit the primary 
degradation mode after early failures being the EVA 
laminating adhesive. So this lifetime can be expected to 
increase. There is some degradation of output over lifetime 
but for poly and mono crystalline cells it is relatively 
small. New amorphous continuous process thin film panels on 
flexible substrates are expected to deliver a cost of around 
$US1 "sometime soon". the panels

Consider an existing technology polycrystalline terrestrial 
panel available off the shelf for about $US5/Watt in
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Marcel Duchamp | 1 Mar 02:04
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Re: [EE[ Favorite R-R Opamp?

Hi Matt,

I don't have a particular number for you right now but do have a lame 
answer: it depends.

One of the specs of most of the Microchip amps is fairly low supply 
voltage, say, 2.2 to 5.5 or so.  If this works for you, great.  If you 
need up to say 12 or so, Microchip has much less to offer.

Second, make sure to check what the output does when sourcing or sinking 
current.  Some amps suddenly develop inability to get to within 500mV or 
more of the rails if asked for as little as a half milliamp.

Probably next on my list of specs to be aware of is speed.  Many low 
power rail-rail amps poop out at a few 100kHz of gbw.  And so it goes.

Good luck!

Matthew Miller wrote:
> Hi Everyone,
> 
> Since beginning work with op-amps, I've found rail-to-rail op-amps very
> useful for battery powered applications. I bet you folks have a favorite in
> this area, but what brand op-amps have the lowest cost?
> 
> I've recently tried the Microchip op-amps and they are pretty good. For some
> of them the offset voltages are awful though, but there not too bad,
> considering the cost.
> 
> Can anyone recommend a line of good rail-to-rail, single supply op-amps? I'm
(Continue reading)

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Herbert Graf | 1 Mar 02:06

Re: [EE]: I am looking for a small positive displacement fan


On Fri, 2008-02-29 at 15:50 -0700, Cedric Chang wrote:
> Here being where ?
> cc

Toronto, Canada, although I'm pretty sure anywhere where it gets cold
enough to need a defrosting of a windshield will have it.

This is specifically the product I'm speaking of:

http://tinyurl.com/335fjq

http://www.canadiantire.ca/browse/product_detail.jsp?FOLDER%3C%
3Efolder_id=1408474396672419&bmUID=1204333464269&PRODUCT%3C%
3Eprd_id=845524443285107&assortment=primary&fromSearch=true

TTYL

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Dario Greggio | 1 Mar 02:16
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Re: [OT] Just wondering..

James Newton wrote:
> http://techref.massmind.org/techref/other/solar/case1.htm my solar panels
> cost $16,000. The system cost $21,000 TOTAL including professional
> installation. I paid $12,759 after rebates. The first year, it made $1,400
> worth of electricity. The panels are warranted for 25 years so they should
> produce $29,400 dollars worth of electricity. And that assumes that the
> price of electricity stays the same; which it has not:
> http://techref.massmind.org/images/other/ePwrRates.GIF

I'm doing the same at my (new) place James (have I already mentioned 
that? :)
the figures in here are roughly the same.
I agree with you.

Though, I'd love easy and cheap nuclear power - I was raised with that 
in mind!

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