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Tsu Do Nimh | 1 Jan 05:05
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Re: [EE] make your own modern capacitor...

s/build/roll/

:)

C.

On 12/30/07, Peter P. <plpeter2006 <at> yahoo.com> wrote:
> William "Chops" Westfield <westfw <at> mac.com> writes:
> > Is it within the reach of "amateur science" to make your
> > own electrolytic or supercapacitor?  An electrolytic is
>
> I think that it can be done but the problem is service life. The exotic
> substances used in electrolytics mostly have to do with longevity in service
> and
> storability. F.ex. Phosphoric acid is used because it modifies the surface
> tension so the electrolyte won't flow out of the separators when stored
> among
> other things. Also the achievable capacitance density by volume may be very
> low.
> E.g. something like 1930s technology: 1 inch dia. 3 inches high maybe
> 20-40uF.
> 'Homemade' Leyden bottle style capacitors are alwasy fairly good and with
> todays
> styro and pvc cups some really powerful designs can be tried.
>
> Anyway rolled foil electrode capacitors are self-made by the high voltage
> crowd
> with good success. An electrolytic can also be built like that. As
> electrolyte I
> think that distilled water with some weak acid in it (phosphoric or boric or
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Apptech | 1 Jan 10:59
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Re: [EE] make your own modern capacitor...

> Is it within the reach of "amateur science" to make your
> own electrolytic or supercapacitor?  An electrolytic is
> more-or-less anodized aluminum foil with a slightly exotic
> electrolyte, and the early supercapacitors were based on
> activated charcoal (which is somewhat available and I 
> think
> even almost home-manufacturable, for somewhat poor values
> of "activated.")

You could probably build a large capacity Tantalum capacitor 
from scratch.
Several of these steps would require investigation but all 
should be within home-builder reach.

- Take Tantalum powder.
- Build a "ball" around an electrode and press into a 
tightly packed mass and then sinter so that all the powder 
forms a mechanical whole.
- Electrically form a thin oxide insulating layer on the 
surface.
- Add an outer conducting layer.
- Add an outer connection and hey presto - a Tantalum 
capacitor with a vast surface area, due to the sintered 
powder, and a very low inter electrode spacing due to the 
oxide separator.

Whether a tantalum capacitor is considered "modern" may be 
moot :-).

        Russell
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John Ferrell | 1 Jan 17:43
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Re: [EE] Toyota TPMS Data Format 315 MHZ

We (me, wife & her twin sister) recently upgraded to 2008 Chrysler Minivans 
with the feature.

The first really cold day my wife calls on the cell and says she has this 
funny icon on the instrument panel that looks like a squiggly line between 
Parentheses brackets. I have her return home for me to investigate (the 
manual is in the car with her!)

Investigating the manual indicates there is a tire below 36 pounds. 
Measurement shows they are at 32 pounds. Specs call for 36 pounds. 
Fortunately I have a compressor in the garage so I set them at 39 pounds. 
Two days later her twins car repeats the scenario. Although it was a 
nuisance at the time I find it a worthwhile gadget. They are more likely to 
eventually see the warning light before a tire is ruined than becoming aware 
of a low tire.

BTW, the spare tire is UNDER the car with its transmitter.

It would be nice to be able to retrofit the feature to my Winnibago.

John Ferrell    W8CCW
"Life is easier if you learn to plow
       around the stumps"
http://DixieNC.US

> Thanks for the further information that another poster
> provided about the data format. I should have tried a little
> more specific search criteria. It sounds like rather than a
> numerical value representing pressure, the output is more of a
> go, no go indication which means your tires could be quite low
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Herbert Graf | 1 Jan 19:04

Re: [EE] Toyota TPMS Data Format 315 MHZ


On Tue, 2008-01-01 at 11:43 -0500, John Ferrell wrote:
> It would be nice to be able to retrofit the feature to my Winnibago.

FWIW you can buy kits that can add this feature to any vehicle, i.e.:

http://tinylink.com/?1uqvN7aI79

http://www.canadiantire.ca/browse/product_detail.jsp;jsessionid=H6AOoaPxTrj0n6no0y2Y2lyV3jP12OVJPYmtb12bcbXcsaZarahQ!-572511605!172915562!7205!7305?postal=l4p3n3&PRODUCT%3C%3Eprd_id=845524443298019&FOLDER%3C%3Efolder_id=1408474396672450&bmForm=form_set_price_list&bmFormID=1199210510298&bmUID=1199210510298&bmHash=46743196e785ecb500a18db9f805e3411d91ebb6

TTYL
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Moses McKnight | 1 Jan 19:35

Re: [PIC] GPL C compiler for PIC

I'm surprised I don't see more people mentioning the Sourceboost
compiler.  It is free for personal use with a 2 K code size limit, but
it works for all supported chips - unlike the Hi-tech "lite" which if I
remember correctly is only good for one or two chips.  Sourceboost also
is good about supporting the latest chips, and their prices are
fantastic compared to just about anyone else with free upgrades.  I'm no
compiler guru but all the reviews I've seen from other people say that
it produces as good or better code than Hi-tech, and it stays closer to
C syntax and supports more features than other compilers.  They also now
have a C++ compiler for PIC chips, which I'll probably get and start
using before too long for some larger projects.

Moses
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Rob Robson | 1 Jan 20:35

[PIC]: best upgrade from 18F452?

Is there a current PIC that's commonly used as a drop-in upgrade from the 18F452, just as the 18F452 seemed to
become the 'new' 16F877 a few years ago?

TIA & HNY,
RR 
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Sean Breheny | 1 Jan 20:47
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[EE]: Noise in spice

Hi all,

One of my favorite programs (which seems to disprove TANSTAAFL) is
LTSpice (aka Switcher CAD from Linear Tech). However, it has me a bit
frustrated lately.

I'm trying to use it to help me design a simple, low-noise audio
amplifier using discrete transistors. It seems that it can do some
noise modeling, but deciphering what it does and does not model is
difficult. It seems that in a normal time or frequency based sim run,
it doesn't include noise at all. When you run the "noise" simulation,
it shows you only noise. It also seems that the only noise it takes
into account is Johnson noise. It doesn't seem to model shot noise at
all (strange as this is fundamental to current flow) and none of the
diode or transistor models included seem to have any flicker noise
parameters (although the sim claims to be able to sim that).

Has anyone here tried to model noise in LTSpice (or any other version
of spice for that matter)?

Thanks,

Sean
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Funny NYPD | 1 Jan 20:57
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Re: [PIC] GPL C compiler for PIC

It doesn’t support the 12F508 and the 16F505. Sad.
It may still need more work to challenge the Hi-Tech PICC. 
Very good price. It also charge version update fee as did the Hi-tech.

Funny N.
New Bedford, MA
http://www.AuElectronics.selfip.com

----- Original Message ----
From: Moses McKnight <moses <at> skytex.net>
To: Microcontroller discussion list - Public. <piclist <at> mit.edu>
Sent: Tuesday, January 1, 2008 1:35:27 PM
Subject: Re: [PIC] GPL C compiler for PIC

I'm surprised I don't see more people mentioning the Sourceboost
compiler.  It is free for personal use with a 2 K code size limit, but
it works for all supported chips - unlike the Hi-tech "lite" which if I
remember correctly is only good for one or two chips.  Sourceboost also
is good about supporting the latest chips, and their prices are
fantastic compared to just about anyone else with free upgrades.  I'm no
compiler guru but all the reviews I've seen from other people say that
it produces as good or better code than Hi-tech, and it stays closer to
C syntax and supports more features than other compilers.  They also now
have a C++ compiler for PIC chips, which I'll probably get and start
using before too long for some larger projects.

Moses
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wouter van ooijen | 1 Jan 21:11
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RE: [PIC]: best upgrade from 18F452?

> Is there a current PIC that's commonly used as a drop-in 
> upgrade from the 18F452, just as the 18F452 seemed to become 
> the 'new' 16F877 a few years ago?

not sure about 'drop in', but 4520 is the direct successor of the 452,
and among the 16F's the 88x are the latest hot-shots.

Wouter van Ooijen

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Matthew Mucker | 1 Jan 21:19

[PIC] Cheapest uC with a UART?

I'm looking for a uC with 8 I/O (including Rx/Tx) and a hardware UART at a
rock bottom price.

The best PIC candidate I could find is the 16F688 which I can get for
$1.28ea in qty 100.

Is there a cheaper part out there? Perhaps a non-Microchip part?  (Of
course, the internal oscillator on the 16F688 does save cost on an external
crystal...)

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Gmane