PRC as a amplifier in GPS question.

[Geoff C]

"Greg the Grog" <shem_an_na@very_warm_mail.com> wrote in
news:L8XPf.1951$dy4.780@news-server.bigpond.net.au:

"Geoff C" <notinterestedin@spam.com> wrote in message
news:Xns97818FC9E7816testnospamcom@61.8.0.29...
Hi,

Has anyone noticed a recent increase in board leakage in FR4 Double
sided boards? We have some high gain preamps that have worked for 8
years no probs, then found leakage on boards from an Aussie and a
Malaysian supplier. This first happened around November.

Are you saying that your circuit boards have incontinence issues (like
Phil ;-)
or are you suggesting that the dielectric constant of FR4 material is
no longer
as constant as you would like?

Should a high gain preamp design be so reliant on substrate material
properties
that manufacturing variations can adversly effect the circuit
performance?

More info pls.
Is it a matching issue, stripline calcs are no longer valid or
dieletric losses are
making your preamp not such high gain?

You say leakage, so I assume you are not flashing an LED with a 555,
but perhaps a little faster. FR4... not above 1GHz if you can get away
with it.

Testing the boards is the only option and make sure there were no
component / supplier changes around about the same time.

Matching / Q gone out the window.... I hate it when that happens.

cheers,
GtG

Frequencies are low, 100 Hz samplin and sqare wave, sensitive to a few
kHz and DC. I measured the baord with a Kiethley electrometer and it is >
100Gohm but I will test more rigorously next week. Yesterday I drilled
the PCB and air connected the opamp node, and all was OK. The f/b R is 10
meg, input is photodiode ground connected. Opamp is OPA404.
Sure, FR4 is not always suitable for high gain, but I would rather stick
with low cost FR4 and air connect the 4 connections to the node. The
board has worked fine for 8 years. Different suppliers no prob. No known
component changes. All contending components were swapped b/n a good and
bad board but prob followed PCB.
Bottom line is I have a fix. I will crunch numbers next week. Good to
have a solid explanation, but at least production is running. BTW, tried
baking and solvent cleaning, and latest baord had guarding artwork on the
sensitive node. Of course, this only works for surface currents.

 

[Who are WE?]

"Clifford Heath" <no.spam@please.net> wrote in message
news:4411180f$0$1052$afc38c87@news.optusnet.com.au...

led displays wrote:
8) Cold light, no UV and heat

Woah, 100% efficient. Better get a patent on those...

Where does it say 100%?

or just bug off, spammer.

 

[Nicholas Sherlock]

Who are WE? wrote:

"Clifford Heath" <no.spam@please.net> wrote in message
news:4411180f$0$1052$afc38c87@news.optusnet.com.au...
led displays wrote:
8) Cold light, no UV and heat
Woah, 100% efficient. Better get a patent on those...

Where does it say 100%?

It says: No UV, no heat. This stating that it converts electricity to
light with 100% efficiency.

Cheers,
Nicholas Sherlock

 

[Phil Allison]

"Omid"
<

What is X2 class?

** A mains cap.

what's it's name known in the market?

** An X2 mains cap.


Now learn to post properly - you fucking Google imbecile.

Click on "options" then "reply" !!!

Or else go drop dead.




........... Phil

 

[swanny]

Nicholas Sherlock wrote:

Who are WE? wrote:

"Clifford Heath" <no.spam@please.net> wrote in message
news:4411180f$0$1052$afc38c87@news.optusnet.com.au...

led displays wrote:

8) Cold light, no UV and heat

Woah, 100% efficient. Better get a patent on those...


Where does it say 100%?


It says: No UV, no heat. This stating that it converts electricity to
light with 100% efficiency.

No it isn't. It simply says no UV and no heat. There are other forms of
energy as well.

It might make a lot of noise ...

 

[Franc Zabkar]

On Mon, 06 Mar 2006 05:45:00 GMT, "Tom Smyth"
<TomS_13@a11.aone.net.au> put finger to keyboard and composed:

History repeating itself.... Looks like Jaycar is following the path of
Tandy (and later Dick Smith, after they successfully filled the void for a
while) with their prices slowly increasing and them selling increasing
amounts of novelties and toys. What is going to fill the void for
enthusiasts and professionals next?

What can a hobbyist build that China can't supply ready made for half
the price? Not much, I'd say.

As for careers in electronics, I think ultimately all design will be
done offshore. So what will there be left for "professionals" to do,
except to emigrate?

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

 

[Tom]

Franc Zabkar wrote:

As for careers in electronics, I think ultimately all design will be
done offshore. So what will there be left for "professionals" to do,
except to emigrate?

Retire.

Tom

 

[Andrew M]

There would be well over $300M worth of electronic equipment designed here in
Australia - the market for professional engineers is still healthy. It is true that
more product is being built offshore to allow competitiveness in world markets, but
Aussies are still highly valued as business partners, designers and innovators.

As for careers in electronics, designers don't just spit out finished products, there
are quality engineers, project managers, component manufacturers, accountants,
financiers, mechanical engineers, manufacturing engineers, technicians, assemblers,
purchasers, distributors and wholesalers etc. that all contribute to a products'
success.

-Andrew M

As for careers in electronics, I think ultimately all design will be
done offshore. So what will there be left for "professionals" to do,
except to emigrate?

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

 

[Peter Parker]

"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
news:vpi412d7ufedisu8mou850hk018r87id3h@4ax.com...

What can a hobbyist build that China can't supply ready made for half
the price? Not much, I'd say.

Heaps of things, especially if they are (i) one-offs and will never be
profitable as a comsumer item, and (ii) meet a small specialised LOCAL need,
especially for business or industry.

A recent example is an LED signal for train signal teaching purpose. The
instructor liked the prototype so much that he bought a bigger version. And
his colleague wants another version, but slightly different.

Sure this $50 signal would retail for $9.99 if mass-produced, but since
there isn't a mass market, the Chinese (or anyone else) aren't going to make
it happen.

There must be other similar unmet needs that aren't widespread enough for
mass production, yet are desired enough that people are willing to pay more
than consumer prices for them.

Peter

 

[Franc Zabkar]

On Sun, 12 Mar 2006 18:34:58 +1100, "Peter Parker" <p@p> put finger to
keyboard and composed:

"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
news:vpi412d7ufedisu8mou850hk018r87id3h@4ax.com...

What can a hobbyist build that China can't supply ready made for half
the price? Not much, I'd say.

Heaps of things, especially if they are (i) one-offs and will never be
profitable as a comsumer item, and (ii) meet a small specialised LOCAL need,
especially for business or industry.

A recent example is an LED signal for train signal teaching purpose. The
instructor liked the prototype so much that he bought a bigger version. And
his colleague wants another version, but slightly different.

Sure this $50 signal would retail for $9.99 if mass-produced, but since
there isn't a mass market, the Chinese (or anyone else) aren't going to make
it happen.

There must be other similar unmet needs that aren't widespread enough for
mass production, yet are desired enough that people are willing to pay more
than consumer prices for them.

Peter

I think you've hit the nail on the head. As far as electronics is
concerned, Australia will be left with specialty boutiques while China
and India will get the department stores. Even so, you may still be
surprised as to what constitutes a viable production quantity.

For example, a friend designs and manufactures a best selling prawning
lamp for the Australian market. The design and testing is nowhere near
as trivial as it may first appear. Many competitors have attempted and
failed to produce a reliable alternative. Because the market is
relatively small, one would have thought that he would have been safe
from serious competition. However, the Chinese have recently attempted
to copy his design, so low production volumes do not appear to be a
deterrent for them.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

 

[budgie]

On Mon, 13 Mar 2006 12:25:42 +1100, Terry Collins <newsonespam-spam@woa.com.au>
wrote:

budgie wrote:
You and I know
that the gizmo is a one-off or will never sell more than a dozen.

I think this is where you and others are wrong. The "chinese" must have
at least a million shops that they can flog their stuff to. This is why
you were told to remove identification marks. Many of these shops will
stock a box and see how it sell. That initial stock is still a good
production run.

When I say that I know the gizmo will only ever sell a dozen, I DO happen to
know my product and the market. Any chinese fab who wants to make a hundred,
thousand, or million is welcome as long as I've already sold that dozen. The
laugh will be on him.

Am I the only person to cruise these $2 shops to see what trinkets are
around?

Probably not, but my product doesn't fall into trinket category. It is a VERY
narrow niche market (remember, "a dozen"?) and even with the most comprehensive
product description/illustration on the packaging they aren't going to sell any.
I'd love to see them try.

Now if it was the next_big_thing (especially in toyland) I'd remove every mark
and clue from the artwork. But it isn't. The key here is knowing the market
before you venture into pcb fab.

 

[Joe G (Home)]

Hi David,

If you want a micro to drive VGA monitor.
http://www.pbjtech.com/ .... in QLD

For Composite video
http://www.necel.com/partic/display/english/document/osd_doc.html

These guys might have stock of both
http://www.adilam.com.au/

J


"David" <dhuisman@bigpond.net.au> wrote in message
news:j%3Rf.4981$dy4.364@news-server.bigpond.net.au...

Hi,

I am looking for a On Screen Display IC for 8-bit micro controller
application that needs to create colour graphics and text on video
monitor.

Preference for unit that can gen lock to external signal as well as
run stand-alone.

A desirable feature (but not essential) is ability to mirror text without
having to create and entire characters set that is mirrored.

The device will later be a production unit so the component source needs
to be wholesale pricing (not Farnell, RS Spares, Digikey etc).

Could someone please recommend a suitable device and possible source in
Australia

Thanks

Regards

David Huisman

 

[Peter Jakacki]

Hi David,
Someone has already mentioned noPC as a possible solution. This product
as well as many others are designed for VGA, not for genlocking PAL/NTSC
monitors.

If VGA is suitable you may consider the Thumbnail VGA module if you are
adding a component to your PCB.

http://www.pbjtech.com/products/index.html#THUMBNAIL_2106_VGA_PROCESSOR_MODULE

Unlike another VGA unit out there this one does not require special
communications framing etc. You can communicate at megabaud rates if you
like or use the SPI or I2C bus. The CPU is a 32-bit ARM7 running at
66Mhz and with the on-board firmware and Forth system is quite capable.

BTW, there is an updated version in the pipeline with on-board external
RAM (vs on-chip RAM) offering much higher resolutions and speed.

*Peter*
http://www.pbjtech.com/

David wrote:

Hi,

I am looking for a On Screen Display IC for 8-bit micro controller
application that needs to create colour graphics and text on video monitor.

Preference for unit that can gen lock to external signal as well as
run stand-alone.

A desirable feature (but not essential) is ability to mirror text
without having to create and entire characters set that is mirrored.

The device will later be a production unit so the component source needs
to be wholesale pricing (not Farnell, RS Spares, Digikey etc).

Could someone please recommend a suitable device and possible source in
Australia

 

[Craig Hart]

yopu want to relace 50c woth of cable and connectors with WHAT??

"J D" <ne1@newhere.com> wrote in message
news:121cdcc6924fr2e@corp.supernews.com...

Hey guys,

I have this keypad with 12 functions (ie 12 micro switches). It needs to
be hard wired with a cable length of 2 meters. RF/IR is out of the
question. The logic signals will go to a micro controller and will
perform functions depending on which button was pressed.

This means that my cable (connecting the keypad to the micro controller)
will need to be 14 core (including power and ground).

This is really not what, because to terminate 14 cores is really hard
work... (I'm lazy...)- not to mention the cost of a 14 pin DIN style
connector...

I'm thinking is it possible, somehow to encode the 12 lines of logic
down to maybe BCD or even 2 wire protocols. This would significantly
reduce my cable core count and makes it easier to assemble.

What do you think?

A) is there a 12 line encoder? (I've seen 4-16 decoders, but not 16-4
encoders)

B) if i could use 2 wire protocols, what would be the way to do it? i2c,
rs232/485, others?

C) dedicated micro-controller? -yuk...

thanks for any suggestion...

 

[J D]

Peter Jakacki wrote:

There are lots of ways but the one that comes to mind immediately is a
simple string of resistors fed back into the micros A/D. You can feed a
current through the string and measure the average voltage to determine
which pedal is pressed (just assuming one at a time at present). Of
course, in this arrangement you would need different value resistors.

Even without an A/D you can add a cap and just measure the RC time
constant.

Oh yeah, and of course there are all the other methods using shift
registers, encoders, I2C, micros etc etc. But the resistor approach
means that you can implement a simple 2 wire daisy chain with each pedal
shorting out the it's resistor in the chain. That way you can tell if
the loop is intact and which pedal is pressed.

An A/D ladder!! yeah.. why didn't I think of that!... nice and simple...
let's see...

1. power line
2. channel
3. ground...

wow.. only 3 wires... I like that...

 

[Craig Hart]

Assuming both AC sources share the same neutral, all you need is two diodes,
a resistor and a flashing LED. Surely your flash-rate isn't THAT critical?

The only downside is that the whole circuit is 'live' and thus needs
adequate insulation to be safe.

Oh, and power disipation would be less than 100 milliwatts.



"Mike" <erazmus@iinet.net.au> wrote in message
news:44166363$0$23288$5a62ac22@per-qv1-newsreader-01.iinet.net.au...

Hi chaps,

Had a small design challenge come up the other day:-

Flash a red or green led 250ms on/250ms off from the
240v AC and provide an 'or' function so if mains switch A
or B are on then the little sucker is powered up and flashes
(rate doesnt change if both and brightness same etc)

Four main criteria are low cost <doh>, to minimise
dissipation, no hot spots exceed 80deg C when
ambient temp is 45 deg C and finally fit in 0.5 cubic inches.
This is for mounting around an induction exhaust fan recess.

I've managed to get it down to about 0.25W but wonder if that
is the limit asymptotically for the class of low voltage devices
needing to run off 240vac, ie Regardless of compenentry there is
going to be a limit vis a vis current to drive the led and then its
just a matter of dropping the voltage by the best method for
the very lowest dissipation.

Is it likely I can get it down to 0.1W to 0.15W ?

--
Regards
Mike
* GMC/VK/VL Commodore & Calais FuseRail that wont warp or melt !
* High grade milspec ignition driver electronics now in development
* Twin tyres for most sedans, trikes and motorcycle sidecars
http://niche.iinet.net.au

 

[Omid]

Thank you All!!!

My Circuit finally worked with your help.

I used X2 Class Cap(0.01u 400V) and R (4W - 170 Ohms)
and it works correctly!
Thanks again.

 

[David]

The OSD device I am looking for would ideally have composite video (1V) out.

It will be interfaced to a PIC18F6720 8-bit microcontroller.

I am looking for IC only that will solder onto the main application PCB.

There will be several modes of operation.
1. Incoming video is bypassed via a switch and routed directly to
composite video out.
2. Incoming Video has text overlayed onto the image and appears on output
3. Graphics and text are created by the micro and the OSD IC is used to
generate comosite vide out in stand-alone mode.

Regards

David

 

[h;hjk]

Phil Allison wrote:

"Craig Hart"

Assuming both AC sources share the same neutral, all you need is two
diodes,
a resistor and a flashing LED. Surely your flash-rate isn't THAT critical?

The only downside is that the whole circuit is 'live' and thus needs
adequate insulation to be safe.

Oh, and power dissipation would be less than 100 milliwatts.




** Really - how ever did you get that ?

240 AC half wave = 170 volts rms.

With R =33 kohms ( = 10 mA peak) = 0.87 watts in the resistor.

The LED is not illuminated constantly. The duty cycle of a flashing LED
is about 10%, so divide your figure by 10, reaching a figure of less
than 100 milliwatts, as stated.

 

[Poxy]

J D wrote:

Peter Jakacki wrote:
There are lots of ways but the one that comes to mind immediately is
a simple string of resistors fed back into the micros A/D. You can
feed a current through the string and measure the average voltage to
determine which pedal is pressed (just assuming one at a time at
present). Of course, in this arrangement you would need different
value resistors.

Even without an A/D you can add a cap and just measure the RC time
constant.

Oh yeah, and of course there are all the other methods using shift
registers, encoders, I2C, micros etc etc. But the resistor approach
means that you can implement a simple 2 wire daisy chain with each
pedal shorting out the it's resistor in the chain. That way you can
tell if the loop is intact and which pedal is pressed.



An A/D ladder!! yeah.. why didn't I think of that!... nice and
simple... let's see...

1. power line
2. channel
3. ground...

wow.. only 3 wires... I like that...

Actually you only need 2: power and the signal wire. You pull the signal
wire low with a resistor so the A/D sees ground normally, and the various
switches pull the line towards the supply voltage via different resistances.
The voltage seen is based on the ratio between the pull-down resistor and
the switch's pull-up resistor.