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To fuse equipment or not to?
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Ken Smith
electronics forum Guru


Joined: 06 May 2005
Posts: 1727

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: ASIC costs Reply with quote

In article <tk9101tkrsunl7ss8u7e5sg9epvb4bn4rt@4ax.com>,
Mike Harrison <mike@whitewing.co.uk> wrote:
Quote:
On Wed, 2 Feb 2005 03:39:00 +0000 (UTC), kensmith@green.rahul.net (Ken
Smith) wrote:

Imagine that you have a circuit involving about fast 8 op-amps (LT1224), a
couple of fast comparitors (LT1016), about 10 discrete transistors and
about 8 polse of filtering. How much are we talking to make an ASIC out
this.

If we also have about 500 macrocells worth of CPLD, an 8051 or so and
about 4Meg of fast RAM. All this runs at about 100MHz. Is it cheaper to
make one ASIC or two.
[....]
Have you looked at the programmable analog parts from Cypress and Zetex ?

Yes but they don't look to be exactly what we need. They may be part of a
multiple chip solution though.

--
--
kensmith@rahul.net forging knowledge
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Ken Smith
electronics forum Guru


Joined: 06 May 2005
Posts: 1727

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: ASIC costs Reply with quote

In article <4200b408$1@news1.ethz.ch>, Rene Tschaggelar <none@none.net> wrote:
[...]
Quote:
Do the comparators work faster than the clock ?

The delay through one of them must vary by less than 4nS.

I can't stand any cogging in the comparitor so it must not be synced to
the clock edge unless the clock is very high. (About 10GHz)

Quote:
Is the filter faster than the clock ?
Yes as things stand it is.


Quote:
Do you need more dynamic range than say 8 bits ?

Yes, at least 16 bits looks to be needed. It may be more depending on how
the quantization interacts with the rest of the system.

--
--
kensmith@rahul.net forging knowledge
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John Larkin
electronics forum Guru


Joined: 29 Apr 2005
Posts: 4320

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: Scope Trigger for digital scope Reply with quote

On Tue, 01 Feb 2005 19:24:26 -0800, mike <spamme0@netscape.net> wrote:

Quote:
dlharmon wrote:
The ADC will be running continuously with the data being stored to
SDRAM (circular buffer). The problem with software triggering is the
aliasing of signals over 40MHz. I plan to use equivalent time
sampling. I should have noted that in the original post. I need the
trigger data so I can know where to put each data point on the screen,
and 12.5ns is not precise enough. For instance, what I need to know is
that the trigger occurred 3.4ns before the 12345678th clock cycle of
the ADC. This is one of those problems I see no digital solution to.

I realize the limitations of undersampling/equivalent time sampling,
and most of them will not matter for this particular application.

Tek has some info on equivalent time sampling here:
http://www.tek.com/Measurement/App_Notes/RTvET/ap-RTvET.html

I will be publishing this design on my website once it is built and
working.

Thanks

Darrell Harmon
http://dlharmon.com/sbc.html


Equivalent time sampling can be extraordinarily difficult and here are
some of the reasons why.

Your trigger system bandwidth has to be as high as the equivalent time
frequency response.

You have many more sources of error and jitter. Individual components
must be a LOT better than the equivalent time resolution multiple to
stay within the total very much smaller error budget.

Your trigger threshold has to be absolutely independent of the input
waveform. Small cycle-cycle variations in the input waveform can cause
catastrophic shifts in the effective trigger threshold even when those
changes happen far outside the area of interest. This is common when
looking at digital signals. Fixing this is harder than it sounds.

So, now that you have your trigger jitter plus A/D timing jitter down to
some fraction of the equivalent time clock interval and it's all
independent of input signal level and waveform, you're ready to build
the interpolator. Oh, don't forget that the aperture time of your A/D
has to be compatible with the equivalent time sampling interval.
Otherwise you'll have excellent time resoluton on a smeared out version
of the actual input.

In the TEK TDS540, they do it this way.
At the trigger event, start two fast positive ramps and store the
acquisition memory reference pointer.
At the next positive clock, start discharging the first ramp at a slower
rate and time how long it takes to discharge.
At the next negative clock, start discharging the second ramp at a
slower rate and time how long it takes to discharge.
This eliminates all the problems you get when the clock and the trigger
are almost coincident. You always have at least one good ramp interval.
But you need two of everything. And you need an absolutely symmetrical
clock.



Darrell's scheme sounds a lot simpler. ADCs are cheap these days.

Just stream samples from both ADCs into FIFOs. One ADC samples the
signal, the other samples a ramp. When you get a trigger, start the
ramp. Everything you need to know is now strolling through the FIFOs.

John
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Mark Jones
electronics forum addict


Joined: 03 Feb 2005
Posts: 61

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: [OT]: Who should God take 1st? Supreme court justice, Pat Robertson, Sponge-Bob, Dr. Dobson, Hillary or Bush? Reply with quote

Paul Burke wrote:
Quote:
Bill Sloman wrote:


Thus, we have another candidate for God's attention, though granting
Scott Stephens performances here, the Devil might be more interested
in him.

On God's recent record, he'll ignore all the obvious candidates and just
kill another 30000 kids.

Paul Burke


Oh but "they're all in a much better place now..."


-- "Welcome to the new millennium, where ingenuity is dead and SpongeBob
Squarepants rules the world..." MCJ 200406
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John Larkin
electronics forum Guru


Joined: 29 Apr 2005
Posts: 4320

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: Coil formula Reply with quote

On Wed, 2 Feb 2005 03:50:39 -0500, Active8 <reply2group@ndbbm.net>
wrote:

Quote:
On Tue, 01 Feb 2005 20:22:19 -0800, John Larkin wrote:

snip

Yup. We had about $20,000 in savings and a steady stream of
unemployment checks. No business plan; they're nonsense.

It's what investors want to see, from my reading. I take it you
didn't borrow any startup capital.

snip
was great fun all around. If you are ever offered help from VCs and
help from the Devil, go with Satan.

LOL. You trusted people called Leeches and you have a bad taste in
your mouth? I've heard nothing negative about VCs until now. What's
the deal?


No, I helped a company, a spinout of the University of Wisconsin, get
going. I designed a heap of electronics for them (they were materials
scientists, mostly) and the deal I had with the founder was that, if
the company was successful, they'd buy the electronics from us. The
electronics would have been just a couple percent of product (a $3
million electron microscope) cost. That was fair: free engineeering in
exchange for being preferred vendor for production. But the founder
spent money like a drunken sailor and burned up the 3F funding
(friends, family, fools) before he could sell anything and had to go
crawling to VCs to survive. Their contracts are a sight to behold:
they own *everything* and the founders and 3Fs get totally screwed.
And they wouldn't honor our deal. So we had a spat. Now I'm working
with their competitors, who are outselling them about 10:1.

Too bad; they were basicly nice people who made beginners mistakes and
had to sell their souls to vicious bastards. At our last meeting, in a
room full of laywers, the founder looked me in the face and lied.
There were too many knives at his back, too much at stake, for honor.

Moral: always own 51%.

John
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Scott Stephens
electronics forum addict


Joined: 21 May 2005
Posts: 62

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: [OT]: Who should God take 1st? Supreme court justice, Pat Robertson, Sponge-Bob, Dr. Dobson, Hillary or Bush? Reply with quote

martin griffith wrote:

Quote:
Hi Scott
1) I'm in Europe
2) I'm an aethist
3) I dont know or care who Pat Robertson is
4) S.E.D in an international english speaking newsgroup, not a US
newsgroup

Please could you post your very OT non electronic ideas to a more
appropriate newsgroup

Who made you the moderator? Who are you to silence me when you have a
kill-file? I'm pissed about government hypocrisy, fascism oppression and
a gang-warfare culture in America. Why shouldn't I speak my mind like
others? You don't have to feed troll.
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Scott Stephens
electronics forum addict


Joined: 21 May 2005
Posts: 62

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: [OT]: Who should God take 1st? Supreme court justice, Pat Robertson, Sponge-Bob, Dr. Dobson, Hillary or Bush? Reply with quote

Paul Burke wrote:

Quote:
Bill Sloman wrote:


Thus, we have another candidate for God's attention, though granting
Scott Stephens performances here, the Devil might be more interested
in him.

On God's recent record, he'll ignore all the obvious candidates and just
kill another 30000 kids.

Nature only managed to kill a few hundred thousand recently. It takes
governments to slaughter hundreds of millions, deliberately with
high-technology, in the name of good intentions.
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Scott Stephens
electronics forum addict


Joined: 21 May 2005
Posts: 62

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: [OT]: Who should God take 1st? Supreme court justice, Pat Robertson, Sponge-Bob, Dr. Dobson, Hillary or Bush? Reply with quote

Mark Jones wrote:

Quote:
Paul Burke wrote:

On God's recent record, he'll ignore all the obvious candidates and just
kill another 30000 kids.

Oh but "they're all in a much better place now..."

Indeed! I just love it when fundees tell you oppression and tyranny is
God's chastening for your benefit. I think any clergy that spouts such
foolishness needs a good dose of suffering and misery themselves.
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rijo1
electronics forum beginner


Joined: 24 Mar 2005
Posts: 1

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: 40 amp power supply ??? Reply with quote

Ok , you guys have talked me out of trying to build the power supply . I thank
you all for patticipating in this discussion . Rick

Tam/WB2TT wrote:

Quote:
"rijo1" <rijo1@nonemonet.com> wrote in message
news:42005573.92C0EC8E@nonemonet.com...
Hi , I need to build a 40 amp power supply that has an input voltage
of 120 volts and an output voltage of 12 volts - 13.5 volts . The power
supply will be used for amateur radio so it needs to be quiet . The
transformer I want to use will come out of a battery charger . I need to
regualte the voltage to DC at the voltages I have specified .
I don't want to use a battery charger and a battery for a power
source .
If anyone has a good design and is willing to send me schematics on
it , please send it to me . Be sure to remove no in front of (
nemonet.com.)
Thanks , Rick

Rick,

Save yourself a lot of trouble and buy a power supply meant for ham radio
use. Astron makes a linear supply that is in your current range. It is
quiet, because there is no fan. Ripple is very low. I have their 70 amp
supply, and it is built like a tank.

I had thought to build my own, but the transformer from Newark cost almost
as much as the whole Astron. See HRO, AES, or TexasTowers for prices. Note
that at 40 A, you can easily spend $50 just for the heat sinks.

Tam/WB2TT
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martin griffith
electronics forum Guru


Joined: 06 May 2005
Posts: 1098

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: [OT]: Who should God take 1st? Supreme court justice, Pat Robertson, Sponge-Bob, Dr. Dobson, Hillary or Bush? Reply with quote

On Wed, 02 Feb 2005 11:00:01 -0600, in sci.electronics.design Scott
Stephens <scottxs@comcast.net> wrote:

Quote:
martin griffith wrote:

Hi Scott
1) I'm in Europe
2) I'm an aethist
3) I dont know or care who Pat Robertson is
4) S.E.D in an international english speaking newsgroup, not a US
newsgroup

Please could you post your very OT non electronic ideas to a more
appropriate newsgroup

Who made you the moderator? Who are you to silence me when you have a
kill-file? I'm pissed about government hypocrisy, fascism oppression and
a gang-warfare culture in America. Why shouldn't I speak my mind like
others? You don't have to feed troll.

I could post my stuff about windsurfing, breadmaking, alt lifestyles,
the substantial problems in EU legislation or my favorite sunsets
here in S.E.D, and it would be pointless, it is a lack of focus on
your part. There are much better places for you to state your points
of view.

Research and define your market more carefully, and it will minimise
effort and maximise what you are trying to achieve.

regards



martin

Serious error.
All shortcuts have disappeared.
Screen. Mind. Both are blank.
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Leon Heller
electronics forum addict


Joined: 30 Apr 2005
Posts: 71

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: hobby pcb fabrication kits Reply with quote

"Rene Tschaggelar" <none@none.net> wrote in message
news:4200e186$1@news1.ethz.ch...
Quote:
Leon Heller wrote:

"Rene Tschaggelar" <none@none.net> wrote in message
news:4200b4b5$1@news1.ethz.ch...

DG wrote:


Any suggestions for starting up a little hobby setup for making PCBs? I
was thinking of getting the MG Chemicals 416-K kit. Comes with 3
sensitized copper-clad (single-sided boards), developer, ferric
chloride,
foam brushes, rubber gloves. Any reason to not use ferric chloride, and
maybe sodium persulfate instead? I'm something economical to make little
boards for PICs and some peripheral circuitry, preferable, it would be
possible to make pads for little ICs SSOP, TSOP, etc...

If you don't know answers but know websites, those are appreciated as
well.

You shouldn't target smaller structures than 15mil
trace width and 15mil trace distance. The narrower holes
shouldn't be below 28mils.


I don't have any problems with 12/12 mil tracks, and can go down to 10
mils, with my home-made PCBs.

On a whole Eurocard ? I faced the problem that etching is
somewhat uneven and while at one side the copper is still
unbroken, at the oder side it already starts to etch under
the varnish. Side means here back/front as well as left/right.

Most of my boards are a lot smaller. I have made a single Eurocard PCB using
12 mil tracks without any problems.

Leon
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keith
electronics forum Guru


Joined: 30 Apr 2005
Posts: 2060

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: A-D front end - robust and for high voltage Reply with quote

In article <Qt_Ld.134653$w62.104419@bgtnsc05-
news.ops.worldnet.att.net>, ng01@att.net.invalid says...
Quote:
"keith" <krw@att.bizzzz> wrote in message
news:pan.2005.02.02.02.54.40.96579@att.bizzzz...

Sure, but "big resistor" isn't so sensitive to "small switch resistance"
and "low bandwith" doesn't have to have the high capacitance of the
FET switches compensated for. It's all about bandwidth.

I'm sorry I haven't been very explicit about what has me baffled. What I
don't understand is how those small switches can take the high voltage
sometimes present. For low ranges I think there has to be a switch near the
top of the divider, right? If so, why doesn't it get fried when there's a
high-voltage input?

I don't believe the switches on a DMM are on the input side, rather in
t he feedback of an instrumentation amp. It would hard to maintain a
multi-megohm input resistance with a resistor divider hanging on.

Someone who is more knowledgeable (has ripped one apart;) could better
comment here. You're right though the few hundred volt input
tollerance is impressive.

--
Keith
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John Larkin
electronics forum Guru


Joined: 29 Apr 2005
Posts: 4320

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: Scope Trigger for digital scope Reply with quote

On Tue, 01 Feb 2005 19:24:26 -0800, mike <spamme0@netscape.net> wrote:

Quote:
dlharmon wrote:
The ADC will be running continuously with the data being stored to
SDRAM (circular buffer). The problem with software triggering is the
aliasing of signals over 40MHz. I plan to use equivalent time
sampling. I should have noted that in the original post. I need the
trigger data so I can know where to put each data point on the screen,
and 12.5ns is not precise enough. For instance, what I need to know is
that the trigger occurred 3.4ns before the 12345678th clock cycle of
the ADC. This is one of those problems I see no digital solution to.

I realize the limitations of undersampling/equivalent time sampling,
and most of them will not matter for this particular application.

Tek has some info on equivalent time sampling here:
http://www.tek.com/Measurement/App_Notes/RTvET/ap-RTvET.html

I will be publishing this design on my website once it is built and
working.

Thanks

Darrell Harmon
http://dlharmon.com/sbc.html


Equivalent time sampling can be extraordinarily difficult and here are
some of the reasons why.

Your trigger system bandwidth has to be as high as the equivalent time
frequency response.


It seldom is. My Tek 11801 can use a 50 GHz sampling head, but its
trigger circuit bandwidth is under 2 GHz. It won't trigger at 50 GHz,
but it will display a 1 GHz rep-rate signal with 50 GHz fidelity. You
always want a scope to have more bandwidth than the reprate of the
signal.

Quote:
You have many more sources of error and jitter. Individual components
must be a LOT better than the equivalent time resolution multiple to
stay within the total very much smaller error budget.

Random jitter adds as a square root/sum of squares sort of thing, so
things aren't all that grim. Even the old tube sampling scopes, like
the HP185, had RMS jitters below 10 ps. The 185 with the 188A
dual-channel sampling plugin had an analog bandwidth of 4 GHz, in
1964.

It's not that hard. I had a student intern build a sampler breadboard
one summer. His soldering and construction were ghastly, but we got a
very clean 70 ps (5 GHz) sampler using fairly ordinary parts. Agoston
Agoston (the guy who did the Tek SD-series heads) retired and started
a little company of his own, Hyperlabs, and did a 20 GHz sampler on
FR-4.


John
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Al
electronics forum beginner


Joined: 05 Jul 2005
Posts: 21

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: photoflash circuit Reply with quote

In article <3620drF4qed6aU1@individual.net>,
"Fritz Schlunder" <me@privacy.net> wrote:

Quote:
"Al" <no.spam@wanted.com> wrote in message
news:no.spam-AE3FC7.11040029012005@news.verizon.net...
In article <pan.2005.01.28.23.00.26.626759@example.net>,
Rich Grise <richgrise@example.net> wrote:

You want strobes? Try small airplane strobes. You can get blinded by
these.

Is that really a selling feature? Something tells me that the OP doesn't
want to be blinded...

Generally speaking though aircraft stuff easily costs ten times what it
seems it aught to cost due to special reliability requirements and the FAA
and whatnot.



If you want power, why screw around.

And the cost was not bad, $160 or so. And it will be reliable.

Al
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John Larkin
electronics forum Guru


Joined: 29 Apr 2005
Posts: 4320

PostPosted: Thu Mar 24, 2005 6:00 pm    Post subject: Re: Sine generator IC solution? Reply with quote

On Wed, 02 Feb 2005 13:15:44 GMT, Fred Bloggs <nospam@nospam.com>
wrote:

Quote:


Tony Williams wrote:
In article <41FD0BE4.2030700@nospam.com>,
Fred Bloggs <nospam@nospam.com> wrote:


You're not going to do much in the way of a 10:1 tuning range in
Wien bridge- fussy little high Q and amplitude unstable thing
that it is. These days the most practical and high performance
approach, at these frequencies, would be to generate a variable
frequency square wave at fundamental and 100x fundamental which
are then processed by cheap switching tracking filter.


An 8038-variety is still the easiest approach if
not much better than 1% THD is ok.

Your approach is nifty and could be very handy if
(say) something like a 2-phase sine/cosine was required.

Note that there is a 3-step square-wave approximation
of a sine which has zero third harmonic content, very
useful if going into a low pass filter.


The switched capacitor filters make an application like this virtually
digital- no analog involved, no tuning, no fussing with voltages, a
simple embedded programming application: Digitally Controlled Sine-Wave
Generator-
http://www.maxim-ic.com/appnotes.cfm/appnote_number/2081

I did that a couple times. It worked well, but the aliasing behavior
of switched-cap filters made them not like the square-wave input and
resulted in some output distortion. A tiny R-C antialiasing filter at
the input (just a cap to ground for the Maxim circuit) can help a lot.

But these days DDS is a whole lot nicer, especially as regards
frequency resolution, range, and parts count. Switched-cap filters can
be noisy, too.

John
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