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Bob Blick | 20 May 2013 18:04

[EE] Toner transfer weirdness

I don't make PC boards at home very often, but when I do it's usually
something simple and I'll do toner transfer with my laser printer.

The method I've had the best luck with is to print onto a piece of
slippery backing paper from labels. I'll tape(using an address label) a
board-plus-size piece of slippery paper to the appropriate place on a
sheet of regular paper and run it through the printer.

But I got a new used laser printer and wow, did it not work! It looks
like the toner did not deposit on the slippery paper at all, stayed on
the roller another revolution, and deposited a few inches further down
the sheet.

I then tried the same process but substituted thin paper from a TIME or
Newsweek magazine. Still taping it to a regular piece of paper by the
leading edge.

This time it printed on the thin paper, strong at the leading edge but
weaker further down.

I tried again, this time cutting a "window" in the plain paper behind
the transfer paper. It worked great.

My working hypothesis is that the transfer charge was getting blocked.

Anyway, for those who do toner transfer, you might try the "window"
method and see if you get better transfer.

Cheerful regards,
(Continue reading)

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RussellMc | 20 May 2013 14:42
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[EE]:: Superb LED longevity & energy cost resources

Reports and data about LED lifetimes and energy cost relative to CFL and
incandescent.

Many claims are made about LED lifetimes under real world conditions.
Products that require certification under stringently tested government
promoted programs are liable to have some credibility. Most others are
suspect.

The Philips lumen maintenance data is for their LEDs only and is definitely
not suitable for inferring the performance of competitors products without
a very good knowledge of hs capable the competitor is. Philips are
currently probably the leading manufacturer in mass market long lifetime
lEDs. Other top competitors achieve similar results but many lesser
competitors products fall well short.

However, Philips data does give useful insight in to the effect of various
factors on likely lifetimes.

__________________________________________

OSRAM & Siemens
Life Cycle Assessment of Illuminants
A Comparison of Light Bulbs, Compact Fluorescent
Lamps and LED Lamps
Executive Summary
November 2009

http://www.osram.hu/_global/pdf/Consumer/General_Lighting/LED_Lamps/Life_Cycle_Assessment_of_Illuminants.pdf

This executive summary is based on a comprehensive LCA report which was
(Continue reading)

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Bob Blick | 19 May 2013 21:33

[PIC] duplicate messages

I've noticed a few duplicate messages today. Usually when this happens
the extra message is a clone, but this time they seem to be twins.

Anyway, I'm looking into it.

Bob

--

-- 
http://www.fastmail.fm - Faster than the air-speed velocity of an
                          unladen european swallow
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James Holland | 19 May 2013 19:09
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Favicon

RE: [EE]: Would you add zeners to automotive PIC analog inputs?

> Hello!
> An ECU uses some PIC analog pins to connect to external sensors
> that return 0 .. 3.3V analog signal, like e.g. a TPS.
> 0603 10uF 6.3V capacitor in parallel to the PIC input, to smooth
> things out.
> Now I wonder if a zener is necessary too, to protect from ESD.
> OK, they won't harm. But are they really necessary in your opinion?
> PCB's are already made and space is little, more hand work is non
> desiderable etc.. so if they are really useful OK, else why add them..
> Thanks,
> Mario

What are your requirements? an engine ECU would usually be required to still operate to some degree with one
sensor shorted to supply or ground. A minimum circuit for an analogue input would typically have an ESD cap
on the input to chassis and a series resistor, I would then use a small dual diode to clamp to rail to handle
short circuits and then an RC filter for anti-aliasing. In the past I have found that using the intrinsic
diode to clamp an input causes big offset problems on the other channels, on one design an input was
accidently driven negative by a sine-wave as the offset voltage was missing - that was discovered when the
other channels were plotted and the negative half of the sine wave was clearly visible.
Regards
James
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Electron | 19 May 2013 13:17
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Favicon

[EE]: Would you add zeners to automotive PIC analog inputs?


Hello!

An ECU uses some PIC analog pins to connect to external sensors
that return 0 .. 3.3V analog signal, like e.g. a TPS.

0603 10uF 6.3V capacitor in parallel to the PIC input, to smooth
things out.

Now I wonder if a zener is necessary too, to protect from ESD.

OK, they won't harm. But are they really necessary in your opinion?

PCB's are already made and space is little, more hand work is non
desiderable etc.. so if they are really useful OK, else why add them..

Thanks,
Mario
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Electron | 19 May 2013 13:17
Picon
Favicon

[EE]: Would you add zeners to automotive PIC analog inputs?


Hello!

An ECU uses some PIC analog pins to connect to external sensors
that return 0 .. 3.3V analog signal, like e.g. a TPS.

0603 10uF 6.3V capacitor in parallel to the PIC input, to smooth
things out.

Now I wonder if a zener is necessary too, to protect from ESD.

OK, they won't harm. But are they really necessary in your opinion?

PCB's are already made and space is little, more hand work is non
desiderable etc.. so if they are really useful OK, else why add them..

Thanks,
Mario
Permalink | Reply | 8 comments |
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David | 19 May 2013 10:42

[PIC] Measuring PIC Vdd with no external components using the FVR

All,

I have written a simple article which might be of use to some people,
measuring the PIC Vdd using no external components.

This builds on an older Microchip application note designed for outdated
parts, so it isn't a new idea. However it works well enough for simple
battery monitoring and can be added to any project on a supported PIC.

You can find it here: http://edeca.net/wp/electronics/measurin
g-pic-vdd-with-no-external-components-using-the-fvr/

Happy to take comments or corrections.

David
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IVP | 19 May 2013 02:08
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[EE] Lichtenberg figures

Hi all,

I saw a very short reference in a clip on Discovery the other day which
was about creating capillaries in proposed bio-engineered organs. It
briefly showed an example of Lichtenberg figures ("captured lightning")
of how a tree structure might be formed. A point source of EHT was
put to the side of an acrylic sheet, causing a feathery breakdown within it

Intrigued, I started looking around

I really like these

http://205.243.100.155/frames/interesting.html

So, how easy is it to make 2MV ? I don't have any recent experience
with Leyden Jars, Wimshurst Machines or Van Der Graaf Generators

Joe
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IVP | 18 May 2013 01:55
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[EE] Uses for stepper motors

Hi all,

I recently offered some surplus stepper motor kits to a school
program intended to foster and mentor the technically-minded

So far there've been no takers, although other items like LCDs,
LEDs and basic components do move quite readily. Shiny things

I made a couple of suggestions, such as an experimenter's wind
turbine (with the motor as the generator, seems a bit of a waste
of a good motor though), a mini-milling machine, X-Y plotter
type things, robotic arms etc

Some of those would require quite some engineering though which
I guess would put the average student off. Probably why the shiny
things are snapped up

The questions is then, what DO you use steppers for. Searching the
web brings up no end of people who can tell you how to drive them
but very few ideas about what to do next

I'd be grateful for any ideas that would help me encourage students
to try stepper motors in a practical and useful project, preferably a
simple one without too much engineering

TIA

Joe
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Manu Abraham | 17 May 2013 16:33
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[EE] anyone know this device ?

Hi,

I got a device (looks a bit optical, due to a lens on it). It is a 3
pin device,
looks much similar to a SL100 (TO39 package) except that there is
no indicator tab as in the case of the TO39 and that no pin is common to
it's metal body. It has a small lens on top of the metal cover. It has
inscriptions on it Toshiba (in Cursive writing) and OS14 and an arrow
pointing to one of the pins.

Does anyone have an idea what device it is ? Possibly a datasheet  ?

Thanks,
Manu
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Djula Djarmati | 17 May 2013 12:52
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[AD] Help wanted in Buenos Aires

Hello,

Our customer will go to Buenos Aires and upgrade some relatively simple 
controller boards. A few SMT components need to be replaced (one TQFP 
ATMEL and a few resistors and chips). He will bring the components but 
not the tools.

He needs someone who has a soldering iron, hot-air soldering station, 
flux, and other small tools to help him do it or rent the tools.

It is possible that this person will be later hired to do these 
modifications by himself.

Please reply to argentina <at> datatehnik.com

Thank you,
Djula
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Gmane