Nabble - PIC - [EE]

Re: Insurgents Hack U.S. Drones

2009-12-17T22:59:15Z

>> But the Pentagon assumed local adversaries wouldn't know how
>> to exploit it, the officials said."
>>
>> Unbelievable.
>
I dunno.

First, the article I read said that all the insurgents had done was
access the broadcast video, which is a pretty long way from "hacking"
in my dictionary.

Second, it implied that the software/equipment to do this was
something you could buy "off the shelf" these days, which was assumed
to be what had been done.

Buying a police scanner doesn't translate to knowing how to exploit
and hack the police radio system...

(not that it isn't useful if you're the one the drone is chasing.)

I made up an original joke on the subject:

"Insurgents in Iraq and Afghanistan have intercepted live video feeds
from Predator drones. They were caught uploading video segments
containing themselves to youtube, facebook, and other internet sites,
and have been referred to their HR departments for possible
disciplinary action."

(my wife thought it was stupid :-())

BillW

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Re: Insurgents Hack U.S. Drones

2009-12-17T20:03:35Z

Not exactly unbelievable. The Pentagon assumes alot that it
shouldn't. There's just too much "old guard" laying in the tech
sector of the DOD.

On Thu, Dec 17, 2009 at 9:52 PM, Vitaliy <piclist@...> wrote:

> Mike Reid wrote:
>> http://online.wsj.com/article/SB126102247889095011.html?mod=WSJ_hpp_MIDDLETo
>> pStories
>
> "The potential drone vulnerability lies in an unencrypted downlink between
> the unmanned craft and ground control. The U.S. government has known about
> the flaw since the U.S. campaign in Bosnia in the 1990s, current and former
> officials said. But the Pentagon assumed local adversaries wouldn't know how
> to exploit it, the officials said."
>
> Unbelievable.
>
> Vitaliy
>
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Re: to-92 LED driver

2009-12-17T19:55:24Z

I have part numbers and data sheets for a number of SMD 3 leaded boost
conveter LED driver ICs. Most of Chinese origin. None that I have seen are
TO92, but that's just a matter of packaging.

I can provide some part numbers and maybe web \sites if interested, but can
derive as good a datasheet yourself as you may be able to get officially in
many cases.

A few quick mentions: Some come in 3 or 4 or 5 pin variants.
Some have direct coil drive or external FET gate drive versions.

Ground
Power in / Inductor / power out to output diode (unless separate pin as
yours has)
Ground
Chip enable - less common - usually active ho=igh so can also be used for
low Vin cutoff.
Voltage sense (rare)

CE6360, CE9908A / HY3100 / VS077A, AY7530xx, eg A7530ER.
Zetex: ZXSC100,

There are two ways to do 3 pins.
One is to have a LED output pin and internal diode.

The nasty and usual way is to connect the LED directly to the
inductor/Vin/LED out pin - LED is fged with pulses of high current.. Death
for most modern LEDs if long lifetin\me is desired.
I pointed this out to Zetex as many of their ap notes show this method. They
didn't answer ;-)

Zetex ZXLD381 is a ttpical example.
It's in SOT23-3 but coul as easily be TO92.
One cell operation (0.9V+)

Zetex ap notes here

http://www.diodes.com/destools/

EUREKA:
http://www.lzmcu.com/uploaddir/porducts%20guild/aicall.pdf
Better http://www.analog.com.tw/pdf/SG09Q1.pdf

AIC1638, AIC1639 AIC1642 seem to be what you want (not xxx2115) and are
available on TO92.
AIC are Tauwanese - I've used some of their products and been duly impressed
with the results.

Whether these products match you product in any way is another matter :-)

R

----- Original Message -----
From: "Dwayne Reid" <dwayner@...>
To: "pic microcontroller discussion list" <piclist@...>
Sent: Thursday, December 17, 2009 1:05 PM
Subject: [EE] to-92 LED driver

> Good day to all.
>
> I recently purchased a LED flashlight that runs from a single 1.5V
> "AA" cell. Upon disassembling it, I see a total of 3 electronic
> components: the LED, a 10uH axial inductor and a 3-legged to-92
> device labelled "TX2115".
>
> I haven't yet tried to measure output current or efficiency but hope
> to do so soon.
>
> My Google search for "tx2115" turns up only one close hit: a Chinese
> site showing that part number and describing it as a Boost LED
> driver. But: the picture is for a 4-legged to-92 device, not 3-legged.
>
> Anyone have any idea where I might find a datasheet for this device
> and, better yet, where to purchase them from?
>
> Thanks!
>
> dwayne
>
> --
> Dwayne Reid <dwayner@...>
> Trinity Electronics Systems Ltd Edmonton, AB, CANADA
> (780) 489-3199 voice (780) 487-6397 fax
> www.trinity-electronics.com
> Custom Electronics Design and Manufacturing
>
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Re: Insurgents Hack U.S. Drones

2009-12-17T19:52:46Z

Mike Reid wrote:
> http://online.wsj.com/article/SB126102247889095011.html?mod=WSJ_hpp_MIDDLETo
> pStories

"The potential drone vulnerability lies in an unencrypted downlink between
the unmanned craft and ground control. The U.S. government has known about
the flaw since the U.S. campaign in Bosnia in the 1990s, current and former
officials said. But the Pentagon assumed local adversaries wouldn't know how
to exploit it, the officials said."

Unbelievable.

Vitaliy

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Re: Best laser printer for PCB designs?

2009-12-17T19:12:35Z

> Meths was used as an abbreviation for methylated spirits, aka denatured
> alcohol I believe. It's usually pink, blue or purple over here due to the
> additives. Must be a British abbreviation :)
>

and Aussie.

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Insurgents Hack U.S. Drones

2009-12-17T17:49:28Z

http://online.wsj.com/article/SB126102247889095011.html?mod=WSJ_hpp_MIDDLETo
pStories

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Re: to-92 LED driver

2009-12-17T14:49:09Z

At 04:05 PM 12/17/2009, you wrote:

Obviously quite a high frequency switcher-- 500kHz or more, most likely,.

You might try contacting the Chinese company, perhaps the photo is in
error; in any case they may be able to help you.

Zetex makes some similar devices, but they are much lower tech- at least
10x as big inductor IIRC.

>Best regards,

Spehro Pefhany --"it's the network..." "The Journey is the reward"
speff@... Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

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Re: to-92 LED driver

2009-12-17T14:34:26Z

At 02:52 PM 12/17/2009, Brendan Gillatt wrote:

>-----BEGIN PGP SIGNED MESSAGE-----
>Hash: SHA1
>
>Dwayne Reid wrote:
> > Good day to all.
> >
> > I recently purchased a LED flashlight that runs from a single 1.5V
> > "AA" cell. Upon disassembling it, I see a total of 3 electronic
> > components: the LED, a 10uH axial inductor and a 3-legged to-92
> > device labelled "TX2115".
> >
> > I haven't yet tried to measure output current or efficiency but hope
> > to do so soon.
> >
> > My Google search for "tx2115" turns up only one close hit: a Chinese
> > site showing that part number and describing it as a Boost LED
> > driver. But: the picture is for a 4-legged to-92 device, not 3-legged.
> >
> > Anyone have any idea where I might find a datasheet for this device
> > and, better yet, where to purchase them from?
> >
> > Thanks!
> >
> > dwayne
> >
>
>It might be a transistor instead. See
>http://www.emanator.demon.co.uk/bigclive/joule.htm

Hi there.

I'm familiar with Big Clive's stuff and have indeed built a couple of
his Joule Thief LED drivers.

But: this is different. Other than the LED, there are exactly 2
other electronic components: a single-winding 10uH axial inductor and
this device.

In other words, much easier to build than the Joule Thief.

FWIW - I have some thin magnet wire (#34 or so) that is actually
comprised of 5 separate strands of much thinner wire. That's what I
used to wind the inductors for my Joule Thief units - much, much
easier to wind. 4 strands in parallel for the main inductor winding
and 1 strand for the feedback winding.

dwayne

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Trinity Electronics Systems Ltd Edmonton, AB, CANADA
(780) 489-3199 voice (780) 487-6397 fax
www.trinity-electronics.com
Custom Electronics Design and Manufacturing

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Re: to-92 LED driver

2009-12-17T13:52:15Z

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Dwayne Reid wrote:

It might be a transistor instead. See
http://www.emanator.demon.co.uk/bigclive/joule.htm

- --
Brendan Gillatt | GPG Key: 0xBF6A0D94
brendan {a} brendangillatt (dot) co (dot) uk
http://www.brendangillatt.co.uk
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Version: GnuPG v1.4.7 (MingW32)

iD8DBQFLKqgPHEhZ5Ws5poERAjn3AJ485Ae0A/+ZGy7ZgmSPS3YmZ0fdSACgrvF2
f/GgNXysgoxI+Kt9QnFzLV8=
=SF/U
-----END PGP SIGNATURE-----
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to-92 LED driver

2009-12-17T13:05:01Z

Good day to all.

I recently purchased a LED flashlight that runs from a single 1.5V
"AA" cell. Upon disassembling it, I see a total of 3 electronic
components: the LED, a 10uH axial inductor and a 3-legged to-92
device labelled "TX2115".

I haven't yet tried to measure output current or efficiency but hope
to do so soon.

My Google search for "tx2115" turns up only one close hit: a Chinese
site showing that part number and describing it as a Boost LED
driver. But: the picture is for a 4-legged to-92 device, not 3-legged.

Anyone have any idea where I might find a datasheet for this device
and, better yet, where to purchase them from?

Thanks!

dwayne

--
Dwayne Reid <dwayner@...>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
(780) 489-3199 voice (780) 487-6397 fax
www.trinity-electronics.com
Custom Electronics Design and Manufacturing

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Re: Human brightness perception and LED's

2009-12-17T04:00:09Z

> I know our eyes have a certain resolution limitation and
> a regular dot the size of a LED would surely not be visible
> at great distances (1-3 miles for example), but I'm not
> sure the same principle applies if the dot irradiates light.

Obviously it does not apply. You can place you point light source in
the farthest nebula, and still it will be visible here provided the
nubber of fotons per second reaching your eye is big enough. Just wait
the fotons to make their path.
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Re: Human brightness perception and LED's

2009-12-17T01:58:03Z

On Wed, Dec 16, 2009 at 5:33 PM, Padu Merloti <padu@...> wrote:
> Does it depend solely on its brightness? I know our eyes have a certain
> resolution limitation and a regular dot the size of a LED would surely not
> be visible at great distances (1-3 miles for example), but I'm not sure the
> same principle applies if the dot irradiates light.

I'm sure it doesn't, given you're not trying to resolve the LED, but
see the light it gives off, which will spread out quite nicely over
the distances you're talking of, even assuming a tight optic. On which
subject, if you just want it to be visible from a certain direction,
then a good optic will vastly increase the brightness in a given
direction.

I'd imagine your basic calculation would first determine what
brightness level you need to be visible in an absolute sense. Then
determine the brightness of your LED at 1m and apply the inverse
squared law, along with an allowance for atmospheric attenuation,
which you will have some of even assuming good clear conditions -
there must be standard rules of thumb for that.

Chris
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Re: [PIC] Directv IR remote control repeater problem - Help.

2009-12-16T14:30:17Z

Mark Perri ha scritto:
> If I may ask, how do you have your PIC modulate your signals to
> transmit? I'm beginning to build a remote control as well. Do you have
> a dedicated port putting out 38 kHz and then another port generating the
> codes, which you gate together with external hardware, or do you have
> one port doing all the work?

I generate it all in software, a 38KHz software PWM amplitude-modulated
(i.e. on-off) by another piece of code.

--

Ciao, Dario
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Re: Human brightness perception and LED's

2009-12-16T10:57:31Z

Check out the standard instrument approach (IFR) runway identify lights,
VASI (Visual approach slope indicator), etc. construction and
brightness. You should be able to find videos of planes making
approaches from some distance and altitude out. At around 5 miles out
height above ground level might be 2200'. About a 3 degree angle if I
remember correctly. You don't say what the application is, but from
5000', even with visual flight conditions (VFR) you might not see any
light from even a bright light.

Padu Merloti wrote:

> My problem is simple: given a certain LED spec, how far will that LED be
> visible without any other relevant obstacles (fog, pollution, etc) or
> obfuscations (think dark night). Assume the LED is being observed at its
> most bright angle.
>
>
>
> Does it depend solely on its brightness? I know our eyes have a certain
> resolution limitation and a regular dot the size of a LED would surely not
> be visible at great distances (1-3 miles for example), but I'm not sure the
> same principle applies if the dot irradiates light.
>
>
>
> I'm designing a sign to be visible from an airplane that could be anywhere
> from 5000 to 15000 ft. The idea is to make an array of LED's, but I wanted
> to make some calculations before actually doing any trial and error.
> Disregarding proportions, the array would look like this, where LED columns
> would be 1 meter apart and rows about 3 inches from each other:
>
>
>
> . . . . . . . . . . . . . . . . . . . . . .
>
> . . . . . . . . . . . . . . . . . . . . . .
>
> . . . . . . . . . . . . . . . . . . . . . .
>
>
>
>
>
> Cheers!
>
>
>
> Padu
>
>

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Human brightness perception and LED's

2009-12-16T09:33:29Z

My problem is simple: given a certain LED spec, how far will that LED be
visible without any other relevant obstacles (fog, pollution, etc) or
obfuscations (think dark night). Assume the LED is being observed at its
most bright angle.

Does it depend solely on its brightness? I know our eyes have a certain
resolution limitation and a regular dot the size of a LED would surely not
be visible at great distances (1-3 miles for example), but I'm not sure the
same principle applies if the dot irradiates light.

I'm designing a sign to be visible from an airplane that could be anywhere
from 5000 to 15000 ft. The idea is to make an array of LED's, but I wanted
to make some calculations before actually doing any trial and error.
Disregarding proportions, the array would look like this, where LED columns
would be 1 meter apart and rows about 3 inches from each other:

. . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . .

Cheers!

Padu

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RE: Stepper Motor Driver

2009-12-15T19:29:40Z

Btw, for the record, the basis of my design is these wonderful people here:

http://dev.www.reprap.org/bin/view/Main/Stepper_Motor_Driver_2_3

DougM

-----Original Message-----
From: piclist-bounces@... [mailto:piclist-bounces@...] On Behalf Of
Josh Koffman
Sent: Sunday, December 13, 2009 8:57 AM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] Stepper Motor Driver

On Sun, Dec 13, 2009 at 11:13 AM, Doug Metzler <doug.metzler@...>
wrote:
> Looking at it now I don't think the 2.2k on top of the 10k pot is right -
> with that combination your Vref max goes way higher than 0.5v, so be
> careful.
>
> I'm going to review it on my board.

My memory of the datasheet is that Vref is 0 to 4V. I'd have to double
check it though. With a 2.2K resistor you could end up a little higher
than 4V.

Josh
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Re: humidity sensing

2009-12-15T13:42:46Z

> On Tue, Dec 15, 2009 at 12:25 PM, AK <00@...> wrote:
> > Haven't used it, but Honeywell makes a capacitive humidity sensor that
> > is just under $6. With a bit of creativity and some functions from a
> > PIC: comparator, timer, A2D with thermistor - a cheap humidity sensor
> > could be devised. Alternatively you could build it into an oscillator
> > and measure the frequency. With this sensor, calibration on a per
> > unit basis is required.
> >
>
> I've used Honeywell capacitive sensors in the past, I don't have time
> to look up the exact number, but they are generally nice parts. I
> believe you can get pre-calibrated units. I'm not sure if this means
> they calibrate the units or tell you the calibration curve.
> (marginally useful in that case)

They tell you the calibration curve. Connect it to a PIC with an AD converter
and EEPROM to store the calibration data. You also need a temperature sensor if
you want to do temperature compensation (not needed if the temperature is
around 25 degrees C all the time). You also need the temperature sensor if you
want to calculate the dew point temperature or the absolute humidity.

What is your application?

/Ruben
==============================
Ruben Jönsson
AB Liros Electronic
Box 9124, 200 39 Malmö, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
ruben@...
==============================

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Re: humidity sensing

2009-12-15T11:47:21Z

On Tue, Dec 15, 2009 at 12:25 PM, AK <00@...> wrote:
> Haven't used it, but Honeywell makes a capacitive humidity sensor that
> is just under $6. With a bit of creativity and some functions from a
> PIC: comparator, timer, A2D with thermistor - a cheap humidity sensor
> could be devised. Alternatively you could build it into an oscillator
> and measure the frequency. With this sensor, calibration on a per
> unit basis is required.
>

I've used Honeywell capacitive sensors in the past, I don't have time
to look up the exact number, but they are generally nice parts. I
believe you can get pre-calibrated units. I'm not sure if this means
they calibrate the units or tell you the calibration curve.
(marginally useful in that case)
The circuit in this case used a 555 oscillator with the sensor as an
active part. The MCU read the duty cycle of the resulting pulse.
--
Martin K.

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Re: humidity sensing

2009-12-15T11:20:40Z

:: Besides the Sensirion SHT11

There is a Sensirion knock off produced natch in an oriental country.

That is how Futurlec have them so cheap.

Of course I'd love a Dallas 1-W humidichrom but at U$76 each, they can
keep them.

Colin
--
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Web presence: www.btech-online.co.uk

Hosted by: www.1and1.co.uk/?k_id=7988359

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Re: humidity sensing

2009-12-15T09:44:47Z

ahhh..cool. I prefer a solution that wont need calibrating since there may be several hundred being made.

Thanks for the pointer!

--- On Tue, 12/15/09, mikin@... <mikin@...> wrote:

> From: mikin@... <mikin@...>
> Subject: Re: [EE] humidity sensing
> To: "Microcontroller discussion list - Public." <piclist@...>
> Date: Tuesday, December 15, 2009, 8:16 AM
> try:
> http://www.chipsensors.com/
>
> Cheers,
> Miki
>
> > Besides the Sensirion SHT11, what other humidity
> sensors are available
> > that others have used? SHT11 is a nice
> interface, works very well BUT...a
> > little $$$ so is there a less expensive solution?
> >
> >
> >
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Re: humidity sensing

2009-12-15T08:32:09Z

The Honeywell HIH series of analog humidity sensors are a bit cheaper...

-marc

On Tue, Dec 15, 2009 at 11:01 AM, alan smith <micro_eng2@...> wrote:

> Besides the Sensirion SHT11, what other humidity sensors are available that
> others have used? SHT11 is a nice interface, works very well BUT...a little
> $$$ so is there a less expensive solution?
>
>
>
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Re: humidity sensing

2009-12-15T08:25:02Z

Haven't used it, but Honeywell makes a capacitive humidity sensor that
is just under $6. With a bit of creativity and some functions from a
PIC: comparator, timer, A2D with thermistor - a cheap humidity sensor
could be devised. Alternatively you could build it into an oscillator
and measure the frequency. With this sensor, calibration on a per
unit basis is required.

On Tue, Dec 15, 2009 at 11:01 AM, alan smith <micro_eng2@...> wrote:
> Besides the Sensirion SHT11, what other humidity sensors are available that others have used? SHT11 is a nice interface, works very well BUT...a little $$$ so is there a less expensive solution?
>
>
>
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Re: humidity sensing

2009-12-15T08:16:22Z

try:
http://www.chipsensors.com/

Cheers,
Miki

> Besides the Sensirion SHT11, what other humidity sensors are available
> that others have used? SHT11 is a nice interface, works very well BUT...a
> little $$$ so is there a less expensive solution?
>
>
>
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humidity sensing

2009-12-15T08:01:43Z

Besides the Sensirion SHT11, what other humidity sensors are available that others have used? SHT11 is a nice interface, works very well BUT...a little $$$ so is there a less expensive solution?

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Re: [PIC] Directv IR remote control repeater problem - Help.

2009-12-14T19:03:48Z

I built a device to decode IR remotes, but I based it on the arduino
platform. The same idea applies to the pic though. I use a 555 timer to
modulate the output since that was the easiest thing to set up and
allows me to just output bits without concern for the modulation. The
way I handled the input was multiple receivers tied to one pin. The IR
receivers like TSOP models are active low so they go low when they get a
signal. I used 3 for the project. One for 36Khz, 38Khz, 40Khz , those
are the main remote frequencies.

On the output I used 3 different pins depending on what modulation the
signal needed. There are ways of doing it with just a micro but this was
a lot easier to code and only required a single chip and a couple 555
timer.

One problem with directv IR signals is that it sends multiple signals
each time you press a button. Even if you have it set for the tv mode,
when you press volume up, it first sends a signal for the sat receiver
to read ( this is how it detects and displays the message, remote is in
tv mode on the screen), it then sends whatever the programmed code is
for the tv. You have to separate those out in the code or it will just
confuse it as to what the protocol is.

This is what the raw output looks like when pressing the some buttons on
my directv remote, - is a low, no - is a high, time is in microseconds.
UP:
Raw (20): -29900 3000 -1150 1250 -1150 650 -550 650 -550 1250 -550 650
-550 600 -1200 1200 -550 1250 -1150 650
DOWN:
Raw (20): -29900 3050 -1150 1200 -1200 600 -550 650 -550 1250 -550 650
-600 1200 -550 1250 -1150 600 -550 650
LEFT:
Raw (20): -29950 3000 -1150 1250 -1150 650 -550 650 -550 1200 -600 600
-600 1200 -1150 1250 -1150 650 -1150 650
RIGHT:
Raw (20): -29900 3050 -1150 1200 -1150 650 -550 650 -550 1250 -600 600
-1150 650 -550 1200 -1150 650 -1150 650

Now notice what happens when I press volume up with the remote
programmed for my tv.
Raw (20): 14722 6000 -1150 1250 -1150 650 -600 600 -1150 650 -1150 1200
-600 600 -1150 650 -550 1250 -1150 650

Decoded NEC: AF548B7 (32 bits)
Raw (68): -16714 9000 -4500 550 -500 600 -550 550 -550 600 -550 550
-1650 600 -550 550 -1650 600 -550 550 -1700 550 -1650 600 -1650 600
-1650 600 -500 600 -1650 600 -500 600 -1650 600 -550 550 -1650 600 -550
550 -600 550 -1650 600 -500 600 -550 550 -550 600 -1650 550 -550 600
-1650 600 -1650 550 -600 550 -1650 600 -1650 550 -1650 600

It sent first a code to the directv receiver to tell it I had pushed a
key, then the code to control volume on my brand of tv. I hope this helps.
Mark H.

Mark Perri wrote:

>
> If I may ask, how do you have your PIC modulate your signals to
> transmit? I'm beginning to build a remote control as well. Do you have
> a dedicated port putting out 38 kHz and then another port generating the
> codes, which you gate together with external hardware, or do you have
> one port doing all the work?
>
> Mark
>
>

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Re: [PIC] Directv IR remote control repeater problem - Help.

2009-12-14T17:55:29Z

Thanks for the link "remotecentral", I'll check that out. Here's a link
to the remote that I started with.
http://diyirrepeater.blogspot.com/

Mine has a few minor changes, and modified that "C" firmware slightly as
well. All my stuff is available on request. This is a 6 port setup.
There are 6 input ports that watch for a signal. The PIC sets a flag
when there is a signal. As long as the flag is set (square wave high)
all of the 6 outputs that have IR LED's are pulsed with a timing loop.
It's all done in software. The "C" program is good documented. If you
need anything else let me know. :)

Mark Perri wrote:

> Carl,
>
> I don't have personal experience with the directv remote, but have you
> checked out http://www.remotecentral.com/ ? They have a lot of info on
> codes and protocols; someone there may be able to help you out.
>
> If I may ask, how do you have your PIC modulate your signals to
> transmit? I'm beginning to build a remote control as well. Do you have
> a dedicated port putting out 38 kHz and then another port generating the
> codes, which you gate together with external hardware, or do you have
> one port doing all the work?
>
> Mark
>
> On 12/12/2009 8:46 AM, Carl Denk wrote:
>
>> I have an IR repeater based on a 18F4320 PIC, an Osram SFH 5410-38-Z IR
>> or equivalent detector that filters the 38 KHz carrier modulation, and
>> an IR LED transmitter. The PIC modulates the output. This all works good
>> with most IR (TV, VCR, DVD, etc.) equipment, but the Directv (older RCA
>> and new HR-21) equipment doesn't use modulation. If I replace the IR
>> detector with a plain photo detector, I can't get a range of more that a
>> couple of feet where I need 10 feet. The unit has 6 channels and
>> everything needs to be controlled from everywhere which prevents
>> programming a signal from 1 channel to output a modulated or not signal.
>> I haven't tried amplifying the photo detector output, but seem to think,
>> the noise from lights and sunlight will become a factor and not be usable.
>>
>> Any thoughts would be appreciated.
>>
>>
>
>

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Re: [PIC] Directv IR remote control repeater problem - Help.

2009-12-14T15:14:04Z

Carl,

I don't have personal experience with the directv remote, but have you
checked out http://www.remotecentral.com/ ? They have a lot of info on
codes and protocols; someone there may be able to help you out.

If I may ask, how do you have your PIC modulate your signals to
transmit? I'm beginning to build a remote control as well. Do you have
a dedicated port putting out 38 kHz and then another port generating the
codes, which you gate together with external hardware, or do you have
one port doing all the work?

Mark

On 12/12/2009 8:46 AM, Carl Denk wrote:

> I have an IR repeater based on a 18F4320 PIC, an Osram SFH 5410-38-Z IR
> or equivalent detector that filters the 38 KHz carrier modulation, and
> an IR LED transmitter. The PIC modulates the output. This all works good
> with most IR (TV, VCR, DVD, etc.) equipment, but the Directv (older RCA
> and new HR-21) equipment doesn't use modulation. If I replace the IR
> detector with a plain photo detector, I can't get a range of more that a
> couple of feet where I need 10 feet. The unit has 6 channels and
> everything needs to be controlled from everywhere which prevents
> programming a signal from 1 channel to output a modulated or not signal.
> I haven't tried amplifying the photo detector output, but seem to think,
> the noise from lights and sunlight will become a factor and not be usable.
>
> Any thoughts would be appreciated.
>

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Re: [PIC] Directv IR remote control repeater problem - Help.

2009-12-14T14:53:09Z

To look at the wave forms, I use the PC Mic. input, and Audacity, that
displays the wave forms on the screen and allows saving and viewing 4
different samples. The receiver is just a simple photo diode, so not to
filter the carrier. When pointing the Directv TV remote and hitting a
key (say "3"), there is a definite square wave with slight sloping
rises and falls. There is flat tops and bottoms. Using a typical (have
tried more than a few) remote, the high has a carrier with say 8 or 15
cycles of a saw tooth superimposed.

I guess it would be possible to recognize the digital identifier of the
Directv, and then sen eithe a square or carrier signal, but that is much
more work, unless someone has done it previously and all necessary is to
port the application, of course do only what is legal. :)

Barry Gershenfeld wrote:

> I think you're going to have to discover how that thing communicates
> "without modulation". ;-) I suspect you're referring to the 38KHz signal
> as the "modulation". (Probably should call it the "carrier"). But any
> attempt at straight-through analog amplification is going to be plagued by
> the noise from stray lights as you pointed out. So you're going to have to
> discover what the receiver is looking for, and detect, and repeat that, much
> as the previous scheme did.
>
> So, maybe it uses baseband codes without a carrier? My first IR control
> from a TV made in 1976 by GE used discrete frequencies in the 40-50KHz
> range. So the receiver had to decide which frequency you were throwing at
> it.
>

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Re: [PIC] Directv IR remote control repeater problem - Help.

2009-12-14T14:28:20Z

I think you're going to have to discover how that thing communicates
"without modulation". ;-) I suspect you're referring to the 38KHz signal
as the "modulation". (Probably should call it the "carrier"). But any
attempt at straight-through analog amplification is going to be plagued by
the noise from stray lights as you pointed out. So you're going to have to
discover what the receiver is looking for, and detect, and repeat that, much
as the previous scheme did.

So, maybe it uses baseband codes without a carrier? My first IR control
from a TV made in 1976 by GE used discrete frequencies in the 40-50KHz
range. So the receiver had to decide which frequency you were throwing at
it.
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Re: Performance Characteristics of Lithium-Ion Cells for NASA's Mars 2001 Lander Application

2009-12-14T13:50:20Z

I think I would describe that reaction as "chemistry". 8-) And thanks to
Jack for citing at least one example of my harebrained idea in actual use.
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Re: Best laser printer for PCB designs?

2009-12-14T11:07:05Z

On Mon, 14 Dec 2009 10:30:23 -0500, Sean Breheny wrote:

> Thank you for the very detailed post, Peter. Just one question:
> exactly what chemical do you mean by "meths"? Methl-ethyl keytone?
> Methyl Chloride? Methyl alcohol?
>
> Sean

Hello Sean.

I hope it was useful; it took quite a bit of experimenting to get a reliable
and reproducible method, so hopefully will be beneficial to somebody in
written form.

Meths was used as an abbreviation for methylated spirits, aka denatured
alcohol I believe. It's usually pink, blue or purple over here due to the
additives. Must be a British abbreviation :)

Regards,

Pete Restall
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Re: Low-temp lead-free solders

2009-12-14T10:17:13Z

Quoting Vitaliy <piclist@...>:

> PICdude wrote:
>
> Have you considered approaching the problem from another angle? We doubled
> the number of heating elements in our poor man's oven by combining two ovens
> into one.
>
> Vitaliy
>

It's not really a problem, but a curiosity. I actually did find a
source selling the same heating elements that they used in the oven,
and I can fit them in there, but no need to mess with that for now, as
I just want to know if it would do it if I ever need it.

Cheers,
-Neil.

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Re: Low-temp lead-free solders

2009-12-14T09:00:11Z

PICdude wrote:

> So I figured out the reflow oven and have it operational, so now I'm
> investigating/experimenting with profiles etc. Also ordering a
> thermocouple to profile the oven.
>
> In the meanwhile though, I discovered that there are lower-temp solder
> pastes available nowadays, and some of these allow me to do lead-free
> with this oven. But each type has it's pros and cons, and I'm
> wondering if anyone has any recommendations on specific brands/models
> they've used. Should about 450 deg-F or less melting point (this oven
> should do 500 deg-F) with no-clean flux. I may be okay with
> water-soluble flux too.
>
> I really don't need lead free currently, but curious to run some tests
> and see how it works out.

Have you considered approaching the problem from another angle? We doubled
the number of heating elements in our poor man's oven by combining two ovens
into one.

Vitaliy

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Re: Best laser printer for PCB designs?

2009-12-14T07:30:23Z

Thank you for the very detailed post, Peter. Just one question:
exactly what chemical do you mean by "meths"? Methl-ethyl keytone?
Methyl Chloride? Methyl alcohol?

Sean

On Sun, Dec 13, 2009 at 12:57 PM, Peter Restall <pete@...> wrote:

>
> On Sat, 12 Dec 2009 13:43:54 -0500, Nathan House wrote:
>
>> Unfortunately, I still can't make PCBs. I can't get the toner to transfer
>> from the paper to the board for the life of me. But that's another post :-)
>
> Evening Nathan.
>
> Lots and lots of scrubbing - before you put your layout to the board, that is.
> The copper clad board needs to be spotless. I use a pan scrub (nylon ?) for
> this, with washing-up liquid - that takes away the grease and layer of
> oxidation; the water ends up black afterwards, unless it is a new piece of
> board. After that I dry the board with kitchen roll (doesn't leave bits of
> fluff or other particles behind) and then give the board a wipe with some
> meths, again using a piece of kitchen roll. Keep wiping with meths until
> there is no blackness on the kitchen roll from the board.
>
> After that I'm ready to press. After attaching the schematic (a bit of
> masking tape does the trick, but be careful where you put it - it will melt
> and the adhesive will not come off easily; it's also etch resistant, so don't
> get it on the copper side !) I put the board onto a hard and flat surface
> between two pieces of grease-proof paper - this is to protect the iron mainly.
> I then put the iron in place on the board and lean heavily onto it for one
> minute without moving it, then after that I'll 'iron' the board - side to
> side, up and down, using the edge of the iron mainly. This bit takes about
> another minute or so.
>
> Once the ironing's done, I chuck the (very hot) board into some cold water
> (no soap or anything - some people say it makes the paper peel better, but
> I've had mixed results). After a minute or two soaking, most of the paper
> peels away; what's left can be scrubbed off with a toothbrush. The brushing
> can be done with a little pressure, but don't overdo it; if there is no
> pressure and the toner is peeling away, your board probably wasn't clean
> enough or the toner is not the right sort.
>
> The paper does not have to be completely removed; in fact, I tend to stop
> brushing even when there are still plenty of gaps covered by a layer of paper
> since too much brushing will eventually start to lift the toner. When the
> board dries out after taking it out of the water, the bits between the tracks
> will turn white and brittle; they're easily removed with a scalpel. The bits
> of paper left over the toner are of no concern. Take the opportunity to touch
> up any holes with an indelible marker pen too; some types of paper will bleed
> the ink though, but if you've chosen the right type of paper then you should
> be fine. You should now be ready for etching.
>
> The paper I use is the glossy stuff from advertising pamphlets, brochures,
> etc. that's pushed through my door. I tried quite a few different types, but
> this works a treat and is free. I try to find some that is mainly white; any
> printing already on the paper doesn't tend to affect the etching, but it's not
> good when you're trying to spot pinholes, defects, etc. after ironing. This
> paper peels peels nicely too (photo paper seemed to be impossible to remove,
> regular paper seemed to be very fibrous but peeled OK, for example).
>
> Also, when you tell your printer to print, make sure that you set it up
> accordingly; for example, I tell mine that I'm printing on transparencies
> even though I'm not - this is because it lowers the fixing temperature when
> printing IIRC, so the toner should lift easier. I also set the print density
> to maximum, toner saving mode to off, page protection of, and I use 1200dpi
> resolution (not the interpolated '1200HQ' mode either).
>
> I've been using this method a fair while, and the last four weekends or so
> I've been knocking up some quick test fixtures for my current project; the
> copper clad board I am using for these is over 20 years old and black, but it
> scrubs up brilliantly and etches fine with how I've outlined above. I've
> also done double-sided boards with this method too. The key is getting it
> really clean I believe.
>
> A few months ago I posted some queries on toner transfer and some of my
> findings to the piclist; search the archives and you might find the thread.
> I seem to remember Vitaliy making some good suggestions at the time that I
> didn't try - you may want to give them a whirl.
>
> Also, make sure you use an old iron. For my first few attempts I decided
> to spice things up with a bit of 'Danger PCB-ing' and used the girlfriend's
> best iron. I broke it by leaning on it too hard, and then had to buy her a
> brand-spanking-new super-deluxe (and pricey) model...
>
> Regards,
>
> Pete Restall
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Re: Stepper Motor Driver

2009-12-13T15:39:33Z

Ok better chance here for $13.65 ea though
http://www.bdent.com/search/part.jsp?partnum=SLA7078MPR
Gaston

Gaston Gagnon wrote:

> Hi Josh,
> Have you look at the allegro SLA7078MPR? $7.51 Newark qty 1
> http://www.newark.com/allegro-sanken/sla7078mpr/ic-motor-controller-zip-23pin/dp/87K4956?Ntt=SLA7078MPR
> It works with unipolar motor only but it's very popular in stepper driver circuit.
> Gaston
>
>
> Josh Koffman wrote:
>
>> On Sun, Dec 13, 2009 at 4:33 PM, PICdude <picdude3@...> wrote:
>>
>>
>>> Have you looked at the LM18245 -- I picked up some of these some time
>>> ago, chosen because of their relatively higher current and voltage.
>>> AFAIR it does bipolar and unipolar.
>>>
>>>
>> Thanks for the suggestion. I don't think I'll need the higher current,
>> but I had a look anyway. They seem to be the LMD18245 by the way. In
>> any case, they seem alright, a bit pricey though. Plus they say
>> they'll only do one phase, so you'd need two of them.
>>
>> Thanks for the suggestion though!
>>
>> Josh
>>
>>
>
>

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