PRC as a amplifier in GPS question.

[D from BC]

On Sat, 3 May 2008 22:04:53 +1000, "David L. Jones"
<altzone@gmail.com> wrote:

I just saw Ironman at the movies - awesome stuff.
Oodles of leading edge technology gadgets in it, some plausible, others not
so plausible.
Definitely a must-see movie for any electronics and techno gadget buff.
Gotta love any movie with soldering iron action.
Deserves all the rave reviews it's been getting.

Dave.

Superman is just some guy flying around in his underwear. It's too
fantastic.

Ironman is a technological achiever working with cool sh*t.
(I'm sure many are in electronics just for the cool factor.)

Some appeal of Ironman is that it's about a man and his machines.
Like boys playing with dump trucks in the sand box.

Question is: Is this a date movie?

I think not..


D from BC
British Columbia
Canada

 

[dmm]

On Sun, 4 May 2008 09:42:53 +1000, "David L. Jones" <altzone@gmail.com> wrote:

"Trevor Wilson" <trevor@_SPAMBLOCK_rageaudio.com.au> wrote in message
news:683s1nF2qlt53U1@mid.individual.net...

"David L. Jones" <altzone@gmail.com> wrote in message
news:481c54f7$1@dnews.tpgi.com.au...
I just saw Ironman at the movies - awesome stuff.
Oodles of leading edge technology gadgets in it, some plausible, others
not so plausible.
Definitely a must-see movie for any electronics and techno gadget buff.
Gotta love any movie with soldering iron action.
Deserves all the rave reviews it's been getting.

**If it's nearly as good as No Country For Old Men, I might go see it. So,
the question is: Is it nearly as good (I don't expect it to be as good)?

Hmm, hard to compare with a dark evil guy going around shooting people with
a pneumatic air gun.
But ironman has more cool weapons and toys. So yeah, it's almost as good I
recon, definitely more fun. Ironman is funny too, real funny.
If you are after performances, Robert Downey Jr is simply brilliant.

Dave.

It's already on the 'net.

Btw, Dave, how's the Calcwatch release coming?

For those on sed who don't know about Dave's watch,
http://www.calcwatch.com/index.html

regards
David

 

[Kev]

Saab C900 Viggenist wrote:

Kev <kevcat@optunet.com.au> writes:

Jason James wrote:
"Toby Ponxenby" <me@privacy.net> wrote in message
news:fv0oto$j1h$2@registered.motzarella.org...
On Sun, 27 Apr 2008 07:27:19 +1000d, Jason James Blathered on
in48139e32$0$23382$c30e37c6@pit-reader.telstra.net:

"Mot Adv" <mot.adv@internode.on.net> wrote in message
news:8ZqdnemFgYWjMY_VnZ2dnUVZ_u-dnZ2d@internode...
400Mhz, future of UHF CB et al
Discussion:-

http://www.austech.info/communication-devices/4945-12-5khz-uhf-
cb.html#post40513
See Page 36 of the Pdf download re 12.5Khz channel spacing, see link
within.
http://www.acma.gov.au/WEB/STANDARD/pc=PC_311117

The closing date for submissions is 18 July 2008.
Any increase in operating freq, will cause an increase in path-loss or
propagation loss. There are advantages ie more channels can be obtained.
A rough formula is: Prop-loss in dbs = 32 + 20log km (in kilometres) +
20log f (megahertz)
To find the difference in path loss due freq increase, keep the distance
the same, then include the original freq in use. Note the answer,..then
insert the new freq. Subtract first value from the second,..and you have
your loss due freq increase in dbs. To obtain a useful value which
conveys an easily, you need to understand decibels (db). For example 30
db is 1000 times the original figure, 3db is twice the original figure.
Google up a db to linear conversion.

Jason

Jason
But... but..
The mooted idea is to decrease the channel intervals - that won't change
anything but the 'requirement' for radios to be better at what they do in
terms of adjacent channels being a problem.
True, there will have to be reduced BW to stop adjacent ch splashing
dev.peaks into the ones either side. plus any reduction in channel spacing
will mean less deviation and therefore a degradation of Sig/Noise.


Will this mean the end of those piss poor Uniden radios that have a
front end so open you can hear every transmission in the 400-500MHz range??

Not just Unidens. GME's products are designed deliberately so that
additional listen-only channels can be programmed anywhere betweek about 450
MHz and 520 MHz. Dunno if that's by design or just a 'feature' that they
decided to use to commercial advantage. I'd say it's by design.

Craig.

yeah but the Uniden radios will let you hear every signal all at the
same time, and on every channel you select
so all you hear is a terrible crashing warbling screeching noise
and that is not a feature it's by design, a very bad design



Kev

 

[Klompmeester]

"Rod Speed" <rod.speed.aaa@gmail.com> wrote in message
news:67nnauF2paok8U1@mid.individual.net...

Saab C900 Viggenist <c900@lios.apana.org.au> wrote
Snapper <snapper1@y7mail.com> wrote

Who of you owns a GPS, or more specifically a car navigator?

Tom Tom, a Netherlands based company has reported 80 percent reduction
in revenue.

Hardly surprising given the price drops you list below
when you allow for the cost to the manufacturer as well.

One of the reasons cited is that while prices have dropped, volume
of sales hasn't increased in proportion to maintain profit levels.

It would be a hell of a lot more surprising if it had with that sort of a
price drop, stupid.

This is because the market is probably saturated, an analyst said.

Wota terminal fuckwit. The other obvious change over
time is the vast number of cheap chinese knockoffs
you can get now which use the same map databases.

Thing is, I know of very few people who own GPSes

Virtually everyone I know has one.

and I move in circles where people tend to buy gadgets and modern
appliances.

Your problem.

So, who is buying the bloody things.

Anyone with a clue.

Anyone with a clue uses a roadmap and their memory.

 

[David L. Jones]

"Klompmeester" <whowhere@andwhy.com> wrote in message
news:KMGdnVbhl5ztQYDVnZ2dnUVZ_u6dnZ2d@internode...

"Rod Speed" <rod.speed.aaa@gmail.com> wrote in message
news:67nnauF2paok8U1@mid.individual.net...
So, who is buying the bloody things.

Anyone with a clue.

Anyone with a clue uses a roadmap and their memory.

They can be incredibly useful.
For instance, try navigating in a foreign country on the wrong side of the
road with a paper street directory, it's a nightmare, especially if you are
going to small non-tourist/non-signposted locations. With the GPS you barely
have to take your eyes and concentration off the road, even more so when you
are the only one in the car. Only a fool would hire a car these days and not
spring the small extra for the GPS option.

I don't have one in my own car yet, because I see less need for it in my own
city which I know well. But every time I've hired a car and GPS in another
country I've been completely sold on their incredible usefulness.

Dave.

 

[legg]

On Mon, 5 May 2008 21:24:43 +1000, "Phil in Melbourne"
<reply@tonewsgroup> wrote:

This is where the question comes in. I am looking at the option of using the
IRS2001 to switch the high side fet. But looking at the datasheet, I am
confused. How can the IRS2001 generate a voltage greater than VCC without
actually being connected to the high side voltage????? There is no talk of a
charge pump in the description and in any case it does not know what
potential the fet is connected to..

Maybe it is not suitable for my application as the IRS2001 seems to be used
for switch mode power supplies? I can't make sense of the first diagram on
the datasheet.

here is a link to the datasheet:

http://www.irf.com/product-info/datasheets/data/irs2001spbf.pdf

For your application, VCC will connect to "up to 200V" in the

application schematic, on page #1. The drive supply VB is
conventionally bootstrapped using the diode in the same drawing.

RL

 

On May 5, 7:24 am, "Phil in Melbourne" <reply@tonewsgroup> wrote:

So I would have thought that this would be a simple problem but the more
information I get the more I get confused......

I want to PWM a whole lot of LEDs. The current consumption of the bank of
LEDs is in the order of 15 Amps, at 12V.

For reasons I won't go into, my only option is to use a high side mosfet.

I have chosen an N-channel MOSFET (IRL3803) mainly because of its huge
current capability and very low on resistance of 7 milli ohms.

I am hoping to use PWM at a reasonably high frequency, say 20khz or higher,
and I want to use an efficient MOSFET driver IC that is designed for the
job.

Why so high? If it's just for brightness control, you don't need that
surely?

 

[Jamie]

Mark wrote:

On May 5, 9:36 am, a7yvm109gf...@netzero.com wrote:

On May 5, 7:24 am, "Phil in Melbourne" <reply@tonewsgroup> wrote:


So I would have thought that this would be a simple problem but the more
information I get the more I get confused......

I want to PWM a whole lot of LEDs. The current consumption of the bank of
LEDs is in the order of 15 Amps, at 12V.

For reasons I won't go into, my only option is to use a high side mosfet.

I have chosen an N-channel MOSFET (IRL3803) mainly because of its huge
current capability and very low on resistance of 7 milli ohms.

I am hoping to use PWM at a reasonably high frequency, say 20khz or higher,
and I want to use an efficient MOSFET driver IC that is designed for the
job.

Why so high? If it's just for brightness control, you don't need that
surely?


if you strobe LEDs too slow, then it causes a strobe effect if there
is any movement... if you scan your eye past some LED rear car lights
you can get the strobe effect and it is very annoying... even if the
LED is not moving, your eye is always moving

I don't know how fast you need to pulse to avoid this but a few
hundred Hz is too slow. 5 kHz might be OK I don't know...

At 5 kHz you might get audio interference so that is a good reason to
go to 20 kHz.

Mark
32 frames/Sec I believe is the minimum needed to prevent strobe flash in

the human eye.. or some figure like that.



http://webpages.charter.net/jamie_5"

 

[Klompmeester]

"David L. Jones" <altzone@gmail.com> wrote in message
news:481e36ea@dnews.tpgi.com.au...

"Klompmeester" <whowhere@andwhy.com> wrote in message
news:KMGdnVbhl5ztQYDVnZ2dnUVZ_u6dnZ2d@internode...

"Rod Speed" <rod.speed.aaa@gmail.com> wrote in message
news:67nnauF2paok8U1@mid.individual.net...
So, who is buying the bloody things.

Anyone with a clue.

Anyone with a clue uses a roadmap and their memory.

They can be incredibly useful.
For instance, try navigating in a foreign country on the wrong side of the
road with a paper street directory, it's a nightmare, especially if you
are going to small non-tourist/non-signposted locations. With the GPS you
barely have to take your eyes and concentration off the road, even more so
when you are the only one in the car. Only a fool would hire a car these
days and not spring the small extra for the GPS option.

I don't have one in my own car yet, because I see less need for it in my
own city which I know well. But every time I've hired a car and GPS in
another country I've been completely sold on their incredible usefulness.

No question that they can be useful devices, but would you buy one and take
it with you? Not likely when purchasing a map for every continent gets
expensive.

 

[Klompmeester]

"Just JT" <Johnnythor@Hotmale.com> wrote in message
news:481e3fc0$0$28635$9a6e19ea@unlimited.newshosting.com...

"Klompmeester" <whowhere@andwhy.com> wrote:

Anyone with a clue.

Anyone with a clue uses a roadmap and their memory.

~~~~~~~~~~~~~~~
Anyone with a clue won't need a roadmap/street directory either.

Dial a taxi?

 

[swanny]

Fred Bloggs wrote:

So I would have thought that this would be a simple problem but the
more information I get the more I get confused......


I want to PWM a whole lot of LEDs. The current consumption of the bank
of LEDs is in the order of 15 Amps, at 12V.

For reasons I won't go into, my only option is to use a high side mosfet.

I have chosen an N-channel MOSFET (IRL3803) mainly because of its huge
current capability and very low on resistance of 7 milli ohms.

I am hoping to use PWM at a reasonably high frequency, say 20khz or
higher, and I want to use an efficient MOSFET driver IC that is
designed for the job.

I understand that to switch an N channel mosfet on the high side of
the supply line, I have to drive the gate with 10V **more** than the
supply voltage. This is correct yes?

This is where the question comes in. I am looking at the option of
using the IRS2001 to switch the high side fet. But looking at the
datasheet, I am confused. How can the IRS2001 generate a voltage
greater than VCC without actually being connected to the high side
voltage????? There is no talk of a charge pump in the description and
in any case it does not know what potential the fet is connected to..

Maybe it is not suitable for my application as the IRS2001 seems to be
used for switch mode power supplies? I can't make sense of the first
diagram on the datasheet.

here is a link to the datasheet:

http://www.irf.com/product-info/datasheets/data/irs2001spbf.pdf



OK so if the above IC is not suitable, I have been looking at the MAX621.

http://datasheets.maxim-ic.com/en/ds/MAX620-MAX621.pdf

This one looks to be more straight forward. But I'm not sure how this
IC will go with 20Khz switching. There are many **low side** mosfet
drivers that are in the 2 to 7 amp range to ensure that the mosfets
are hard on or hard off within a few nS. This one doesn't look like it
will do anywhere near that switching current.


Any other ideas for a high side N channel driver IC that packs a punch?


You're going about this all wrong, no one makes a dimmable LED supply
like this, the main reason being your excessive ripple current resulting
in unnecessary heating and exponential reduction in LED lifetime.
Another good reason for not doing it this way is to avoid the fairly
huge current spikes resulting from what will be a hefty equivalent load
capacitance producing enough EMI to be detected in another galaxy. And
you want to go to all this trouble to produce a crap design because it's
the only thing you understand. Do some background reading:
http://powerelectronics.com/mag/710PET24.pdf and put more effort into
your planning.

Somebody stuffed up Fig. 2, didn't they.

 

[John Popelish]

Jamie wrote:

32 frames/Sec I believe is the minimum needed to prevent strobe flash in
the human eye.. or some figure like that.

Fine for a stationary source you are staring at. But all
you have to do is blink and you will see a trail of dots
(especially if the LED is very much brighter than its
surroundings) at 32 flashes per second, and a lot faster,
too. If you haven't seen the effect, I suggest you try it.

--
Regards,

John Popelish

 

[terryc]

On Mon, 05 May 2008 21:24:43 +1000, Phil in Melbourne wrote:

I want to PWM a whole lot of LEDs. The current consumption of the bank of
LEDs is in the order of 15 Amps, at 12V.

Can you explain why you can not just break this down into multiple units
all centrally driven? say 15 units drawing 1amp each, or 30 units drawing
500mA?

 

[Rod Speed]

David L. Jones <altzone@gmail.com> wrote:

On May 6, 9:39 am, "Klompmeester" <whowh...@andwhy.com> wrote:
"David L. Jones" <altz...@gmail.com> wrote in
messagenews:481e36ea@dnews.tpgi.com.au...





"Klompmeester" <whowh...@andwhy.com> wrote in message
news:KMGdnVbhl5ztQYDVnZ2dnUVZ_u6dnZ2d@internode...

"Rod Speed" <rod.speed....@gmail.com> wrote in message
news:67nnauF2paok8U1@mid.individual.net...
So, who is buying the bloody things.

Anyone with a clue.

Anyone with a clue uses a roadmap and their memory.

They can be incredibly useful.
For instance, try navigating in a foreign country on the wrong side
of the road with a paper street directory, it's a nightmare,
especially if you are going to small non-tourist/non-signposted
locations. With the GPS you barely have to take your eyes and
concentration off the road, even more so when you are the only one
in the car. Only a fool would hire a car these days and not spring
the small extra for the GPS option.

I don't have one in my own car yet, because I see less need for it
in my own city which I know well. But every time I've hired a car
and GPS in another country I've been completely sold on their
incredible usefulness.

No question that they can be useful devices, but would you buy one
and take
it with you? Not likely when purchasing a map for every continent
gets
expensive.

What's your point?

I'd simply weigh up the cost of a map vs the cost of hiring.

And anyone with a clue gets the maps for free.

If I was going for a 6 month driving tour through Europe it would almost
certainly be cheaper to simply buy the GPS and/or map rather than rent
a GPS over their. If it's just one week, almost certainly cheaper to rent.

Not if you get the map for free it wouldnt be.

Don't need it when you get back? resell it on ebay. I've done that many
times with gear I've taken on trips. Some times I've even re-sold at a profit.

I know people who share their GPS and/or maps with friends when
they go overseas to save cost, just like sharing a lonely planet guide.

 

[David L. Jones]

On May 6, 9:39 am, "Klompmeester" <whowh...@andwhy.com> wrote:

"David L. Jones" <altz...@gmail.com> wrote in messagenews:481e36ea@dnews.tpgi.com.au...





"Klompmeester" <whowh...@andwhy.com> wrote in message
news:KMGdnVbhl5ztQYDVnZ2dnUVZ_u6dnZ2d@internode...

"Rod Speed" <rod.speed....@gmail.com> wrote in message
news:67nnauF2paok8U1@mid.individual.net...
So, who is buying the bloody things.

Anyone with a clue.

Anyone with a clue uses a roadmap and their memory.

They can be incredibly useful.
For instance, try navigating in a foreign country on the wrong side of the
road with a paper street directory, it's a nightmare, especially if you
are going to small non-tourist/non-signposted locations. With the GPS you
barely have to take your eyes and concentration off the road, even more so
when you are the only one in the car. Only a fool would hire a car these
days and not spring the small extra for the GPS option.

I don't have one in my own car yet, because I see less need for it in my
own city which I know well. But every time I've hired a car and GPS in
another country I've been completely sold on their incredible usefulness.

No question that they can be useful devices, but would you buy one and take
it with you? Not likely when purchasing a map for every continent gets
expensive.

What's your point?

I'd simply weigh up the cost of a map vs the cost of hiring.
If I was going for a 6 month driving tour through Europe it would
almost certainly be cheaper to simply buy the GPS and/or map rather
than rent a GPS over their. If it's just one week, almost certainly
cheaper to rent.

Don't need it when you get back? resell it on ebay. I've done that
many times with gear I've taken on trips. Some times I've even re-sold
at a profit.

I know people who share their GPS and/or maps with friends when they
go overseas to save cost, just like sharing a lonely planet guide.

Dave.

 

[David L. Jones]

On May 6, 1:34 pm, "Rod Speed" <rod.speed....@gmail.com> wrote:

David L. Jones <altz...@gmail.com> wrote:



On May 6, 9:39 am, "Klompmeester" <whowh...@andwhy.com> wrote:
"David L. Jones" <altz...@gmail.com> wrote in
messagenews:481e36ea@dnews.tpgi.com.au...

"Klompmeester" <whowh...@andwhy.com> wrote in message
news:KMGdnVbhl5ztQYDVnZ2dnUVZ_u6dnZ2d@internode...

"Rod Speed" <rod.speed....@gmail.com> wrote in message
news:67nnauF2paok8U1@mid.individual.net...
So, who is buying the bloody things.

Anyone with a clue.

Anyone with a clue uses a roadmap and their memory.

They can be incredibly useful.
For instance, try navigating in a foreign country on the wrong side
of the road with a paper street directory, it's a nightmare,
especially if you are going to small non-tourist/non-signposted
locations. With the GPS you barely have to take your eyes and
concentration off the road, even more so when you are the only one
in the car. Only a fool would hire a car these days and not spring
the small extra for the GPS option.

I don't have one in my own car yet, because I see less need for it
in my own city which I know well. But every time I've hired a car
and GPS in another country I've been completely sold on their
incredible usefulness.

No question that they can be useful devices, but would you buy one
and take
it with you? Not likely when purchasing a map for every continent
gets
expensive.

What's your point?

I'd simply weigh up the cost of a map vs the cost of hiring.

And anyone with a clue gets the maps for free.

Don't expect me to admit that I've gotten maps for free before do
you? ;-)

Dave.

 

[Rich Grise]

On Mon, 05 May 2008 21:24:43 +1000, Phil in Melbourne wrote:

For reasons I won't go into, my only option is to use a high side
mosfet.

Aw, c'mon! Why not? This could turn out more interesting than the rest
of the thread!

Thanks,
Rich

 

[Rich Grise]

On Mon, 05 May 2008 20:05:47 -0400, John Popelish wrote:

Jamie wrote:

32 frames/Sec I believe is the minimum needed to prevent strobe flash in
the human eye.. or some figure like that.

Fine for a stationary source you are staring at. But all
you have to do is blink and you will see a trail of dots
(especially if the LED is very much brighter than its
surroundings) at 32 flashes per second, and a lot faster,
too. If you haven't seen the effect, I suggest you try it.

It shows up on scrolling marquees very dramatically - when it's
scrolling, the letters look tilted, but I believe that's an artifact
of the strobing. If you move your eyes to follow the letters, they
square up.

Cheers!
Rich

 

[nospam]

Rich Grise <rich@example.net> wrote:

On Mon, 05 May 2008 21:24:43 +1000, Phil in Melbourne wrote:

For reasons I won't go into, my only option is to use a high side
mosfet.

Aw, c'mon! Why not?

Probably because it is some stupid contraption to go on a car with only the
chassis available as a -ve earth. Probably blow up on the first load dump
it sees anyway .

--

 

[krw]

In article <s9MTj.40$wj3.23@newsfe06.lga>,
jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net says...

Mark wrote:

On May 5, 9:36 am, a7yvm109gf...@netzero.com wrote:

On May 5, 7:24 am, "Phil in Melbourne" <reply@tonewsgroup> wrote:


So I would have thought that this would be a simple problem but the more
information I get the more I get confused......

I want to PWM a whole lot of LEDs. The current consumption of the bank of
LEDs is in the order of 15 Amps, at 12V.

For reasons I won't go into, my only option is to use a high side mosfet.

I have chosen an N-channel MOSFET (IRL3803) mainly because of its huge
current capability and very low on resistance of 7 milli ohms.

I am hoping to use PWM at a reasonably high frequency, say 20khz or higher,
and I want to use an efficient MOSFET driver IC that is designed for the
job.

Why so high? If it's just for brightness control, you don't need that
surely?


if you strobe LEDs too slow, then it causes a strobe effect if there
is any movement... if you scan your eye past some LED rear car lights
you can get the strobe effect and it is very annoying... even if the
LED is not moving, your eye is always moving

I don't know how fast you need to pulse to avoid this but a few
hundred Hz is too slow. 5 kHz might be OK I don't know...

At 5 kHz you might get audio interference so that is a good reason to
go to 20 kHz.

Mark
32 frames/Sec I believe is the minimum needed to prevent strobe flash in
the human eye.. or some figure like that.

Not at all. Movies use 24fps, but open the shutter two or three
times per frame to eliminate the flashing. TV interlaces 30Hz
frames with 60Hz fields for similar reasons.

--
Keith