Driver to drive?

[Spehro Pefhany]

On 6 Nov 2004 09:08:38 -0800, the renowned cffung@myrealbox.com (CFF)
wrote:

<code snipped>

Turn off the WDT or add a CLRWDT instruction in your timing routines
such that it gets hit at least every 7msec (no prescaler).


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

 

[ChrisGibboGibson]

Jim Thompson wrote:

Didn't some old capacitor/condenser microphones use RF oscillation?

I seem to vaguely recall such schemes, but my surfing has come up
nought.

Does anyone have some links?

Sennheiser used RF biasing for some of their condenser mics. Don't know of any
others who did it though. How do I know? Because if the screening was anything
but perfect they, used to beat with harmonics of the bias oscillators in tape
recorders and make a right noise.

No links but you know where to look now.

Gibbo

 

[ChrisGibboGibson]

"Richard Crowley" wrote:

"Jim Thompson" wrote ...
Didn't some old capacitor/condenser microphones use RF oscillation?

I seem to vaguely recall such schemes, but my surfing has come up
nought.

Yes, I seem to recall that some early designs used RF, but likely
nothing in the last 50 years.

I'm *pretty* sure they still make them. Mainly because they sound great.

Gibbo

 

[Rich The Philosophizer]

On Sat, 06 Nov 2004 14:38:43 +0000, Paul Burridge wrote:

On Sat, 06 Nov 2004 01:35:29 GMT, Rich The Philosophizer
null@example.net> wrote:

Well, I have heard that they have a ritual where they mutilate
their male children.

There was a program on TV 'bout it 2 nights ago. In this case, the
snip went too far and the poor boy ended up with no dick! So he was
raised as a girl until age 13 when it all came out. He's been screwed
up ever since. I think it's time all forms of genital mutilation were
criminalised. The situation with young girls in central Africa is
equally despicable. A job for the International Criminal Court,
perhaps?

Child mutilation must be stamped out! Send the Marines!

;^j
Cheers!
Rich

 

[steve]

Jamie Morken <jmorken@shaw.ca> wrote in message news:<qYVid.100511$9b.21073@edtnps84>...

Is that board some type of navigation control for a model rocket? I
fly radio control planes, I couldn't find anything on the site that
talks about it.

It is a homebuilt inertial measurement unit using the Analog Devices
adxrs gyros and adxl accelerometers and a 16bit ADC, and an atmega32
with 4MB of datalogging flash.

Jamie,

Very nice homebuilt, I am wondering how did you solder the BGA device?
Oven? Or an pcb assembly shop?

steve

cheers,
Jamie

 

[ChrisGibboGibson]

Guy Macon wrote:

Joerg wrote:

How can you cancel a post to an unmoderated newsgroup? Just curious.

Send a post using this syntax:

(start)

Newsgroups: sci.electronics.design,sci.electronics.misc
Subject: cmsg cancel <Xqbjd.5537$zx1.2586@newssvr13.news.prodigy.com
Message-ID: <cancel.Xqbjd.5537$zx1.2586@newssvr13.news.prodigy.com
Control: cancel <Xqbjd.5537$zx1.2586@newssvr13.news.prodigy.com
References: <Xqbjd.5537$zx1.2586@newssvr13.news.prodigy.com
Supersedes: <Xqbjd.5537$zx1.2586@newssvr13.news.prodigy.com
X-Cancelled-By: notthisjoergsch@removethispacbell.net
Approved: notthisjoergsch@removethispacbell.net
Sender: notthisjoergsch@removethispacbell.net
From: notthisjoergsch@removethispacbell.net
X-No-Archive: Yes

cancel <Xqbjd.5537$zx1.2586@newssvr13.news.prodigy.com

(end)

****************************************************

Here is a template, ready for you to enter your info:

Newsgroups:
Subject: cmsg cancel
Message-ID: <cancel.
Control: cancel
References:
Supersedes:
X-Cancelled-By:
Approved:
Sender:
From:
X-No-Archive: Yes

cancel

Or just click the cancel button on the newsreader.

In both cases hope no one read it first, which they will have done.

Gibbo

 

[ChrisGibboGibson]

And this *very* recent one came a close second....

You do know that the original ritual called for the circumciser to
staunch the blood flow with his mouth? And then someone was supposed
to eat the foreskin- not sure who.


Does that explain why the israeli government acts like a bunch of
cocksuckers?

Gibbo

 

[Al Borowski]

This link is useful:
http://www.piclist.com/techref/piclist/codegen/delay.htm

cheers,

Al

 

[ChrisGibboGibson]

"Frank Bemelman" wrote:

"ChrisGibboGibson" <chrisgibbogibson@aol.com> schreef in bericht
news:20041106181450.21699.00000226@mb-m12.aol.com...
Guy Macon wrote:


Joerg wrote:

How can you cancel a post to an unmoderated newsgroup? Just curious.

Send a post using this syntax:

(start)

Newsgroups: sci.electronics.design,sci.electronics.misc
Subject: cmsg cancel <Xqbjd.5537$zx1.2586@newssvr13.news.prodigy.com
Message-ID: <cancel.Xqbjd.5537$zx1.2586@newssvr13.news.prodigy.com
Control: cancel <Xqbjd.5537$zx1.2586@newssvr13.news.prodigy.com
References: <Xqbjd.5537$zx1.2586@newssvr13.news.prodigy.com
Supersedes: <Xqbjd.5537$zx1.2586@newssvr13.news.prodigy.com
X-Cancelled-By: notthisjoergsch@removethispacbell.net
Approved: notthisjoergsch@removethispacbell.net
Sender: notthisjoergsch@removethispacbell.net
From: notthisjoergsch@removethispacbell.net
X-No-Archive: Yes

cancel <Xqbjd.5537$zx1.2586@newssvr13.news.prodigy.com

(end)

****************************************************

Here is a template, ready for you to enter your info:

Newsgroups:
Subject: cmsg cancel
Message-ID: <cancel.
Control: cancel
References:
Supersedes:
X-Cancelled-By:
Approved:
Sender:
From:
X-No-Archive: Yes

cancel


Or just click the cancel button on the newsreader.

Which only works on your own messages. You can also cancel
others messages, but it is a bit more work. Typically the work
of automated cancel-bots. I have once written one (revartson)
for a dutch newsgroup, with permission of 99% of the group.
Dangerous tool.

In both cases hope no one read it first, which they will have done.

Yes, you need to be quick

You can cancel others' messages?

I vote you for group moderator.

Gibbo

 

[John Larkin]

On Sun, 07 Nov 2004 03:57:28 GMT, "Ratch" <Watchit@Comcast.net> wrote:

Such was the feeling in Germany circa 1939.

Yes, but what was the reason behind that feeling,

Standard bigotry.

and what did they do
about it?

Standard concentration camps and gas chambers.

John

 

[Steve]

Just wanted to post and thank everyone who helped out. We swapped the
transistors and removed to two 1k base limiting resistors and now the
circuit works perfectly...just like we wanted it to work.

 

[Ban]

Kevin Aylward wrote:

Well, I am currently playing around with simulations of an audio amp
using state of the art bipolar (ft=50Mhz, 15A, 230V, 150W) and its a
no contest. Mosfets switch much faster. I can get 1000V/us (500W
@8ohms) with mosfets, only about 100V/us with bipolar.


Well, with 500W into 8R you will have a +/-90V peak swing, which corresponds

to a slew rate of 11V/us at 20kHz.
max. slew = dU/dt = 2pi*f*Upeak, so what is the problem with these bipolars?
I like the Sanken 2SA1216/2SC2922.

--
ciao Ban
Bordighera, Italy

 

[Kevin Aylward]

Ban wrote:

Kevin Aylward wrote:

Well, I am currently playing around with simulations of an audio amp
using state of the art bipolar (ft=50Mhz, 15A, 230V, 150W) and its a
no contest. Mosfets switch much faster. I can get 1000V/us (500W
@8ohms) with mosfets, only about 100V/us with bipolar.


Well, with 500W into 8R you will have a +/-90V peak swing, which
corresponds to a slew rate of 11V/us at 20kHz.
max. slew = dU/dt = 2pi*f*Upeak, so what is the problem with these
bipolar?

Well, first its difficult to get those magic specs that those audio
goldern ears dudes like. Secondly, its a marketing game, not a reality
game.

Thirdly, this slew rate limit is a bit misleading. You need say, at
least twice what this number says in practice. When an amp is slewing
everything collapses. Class A stages don't want to be run to their full
swings. If an amp is collapsing at 20khz, its recovery time might well
be significant.

I can tell you this, if an amp slews at say, only 25khz, its 20khz/19khz
imd will be quite large. It all goes hand in hand, a low distortion amp
at hf, requires a larger slew rate than what might be implied by simple
overload calculations. That is, an amp that has 0.01% at 20khz, implies
indirectly an associated faster slew rate. The fast slew rate is a
*side* effect of obtaining good hf performance. This seems to be missed
by everyone since Baxendale made his observation of records only
requiring 0.5V/us.

I like the Sanken 2SA1216/2SC2922.

I am aware of these, but I don't have their spice models. I have looked
at the 2SC4001 and 2SA1546 as well, of which I also don't have models
for. I am playing with the Motorola MJL4281/MJL4302. I did have to
adjust the models a bit. Their hfe was a bit optimistic.

My spice designs so far with the mos are quite good. One with a simple
design is doing < 0.01% at 20khz, the second one, with with an extra
special custom feedback loop, is < 0.0004% at 20Khz, acording to spice.
At which point I will say, this. Its hard to accurately analyse x-over
in spice, so I dont know what this will do to the figures yet.
Simulation time for this would take way too long. I use the ac small
signal distortion feature of SS, a feature not available in LTSpice.
This feature I think is indispensable. It allows one to at check that
the class A driver stuff is not limiting performance, and I can assure
you that D.Self's "Blameless" amplifier
(http://www.dself.dsl.pipex.com/ampins/dipa/dipa.htm), isn't. Its just
can't cut it with this level of performance. Indeed below 1khz 1'm
getting, -140db distortion!

Once I'm finished playing, I will post some of the schematics. My ouput
stage is rather novel.

Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.

 

[Pooh Bear]

john jardine wrote:

"Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:418C837D.38906D0B@hotmail.com...
Rich Grise wrote:

On Fri, 05 Nov 2004 21:49:15 +0000, Pooh Bear wrote:

Pinchy wrote:

I am building a waveformgenerator. To increase the output current I
intend to use a push pull class amplifier (NPN - PNP) in the feedback
loop of the last opamp. Hence it has to go up to 100 kHz I am
looking
for the most recommended transistorset to build this stage. It
should
be able to provide up to 15 V / 50 ohm (output resistance) = 300 mA
in
order to get an automatic shortcut protection circuit (50 ohm acting
as a load)

The combination BC457 - BC557 (100 mA) is not suitable. The other
BD139 - BD140 (5A) is giving trouble in high frequency range as the
junctions of these are getting pretty big. The last option is a
BC141
- BC161 (1A) but those are getting pretty old. Has anyone a better
idea (European parts) ? Is it usefull to bypass the collector - base
junction with Schottky diodes (as in digital 74LS, ALS, AS, ...) to
inprove the discharge speed of the collector junction ?

What's the special requirement for 'pro-electron' designation type
devices
exclusively ? Nothing really good that I can think of.

Scared to use anything that starts 2N ? MJ even !

Probably availability of Right- or Left-pondian parts.


I suspect from the grin that you know that's a non-issue. I'm in the UK
and only
use a couple of BC parts regularly in my designs. They happen to be widely
used
worldwide.

The OP may be less well versed in component availability I suspect.

Graham

In UK, for prototyping and development purposes, most people will select
from the RS or Farnell catalogues. If you look at (say) the Farnell "GP amps
and switches" transistor pages it's 95% BC... and ZTX... numbers. So for
simplicity and stock availability, these'll be bought in the first instance.
There's no pro-electron bias, it's just a function of whichever supplier is
giving Farnell/RS the best purchasing deals.

For low power devices - you're possibly mainly right. We used to buy certain
MPSAs from Farnell though.

Look at high power and there's hardly a pro-electron designation device to be
seen. Mainly 'cos there aren't any of note. Indeed I'm barely aware of any
newish pro-electron designation types at all.

Many power devices of note are manufacturer part no type - like the MJs.

For volume production of course it's only the price that matters and each
device can be looked at for possible re-spec using worldwide sources.

Also, there are quite specific devices that are application specific. I would be
lost without certain 2 SAs for example.


Graham

 

[Pooh Bear]

Kevin Aylward wrote:

Well, I am currently playing around with simulations of an audio amp
using state of the art bipolar (ft=50Mhz, 15A, 230V, 150W) and its a no
contest. Mosfets switch much faster. I can get 1000V/us (500W @8ohms)
with mosfets, only about 100V/us with bipolar.

And such slew rates are relevant to audio in *which* way ?


Graham

 

[Pooh Bear]

Klaus Vestergaard Kragelund wrote:

The reason MOSFETs are used in switch-mode
supplies are more that they are easy to drive (no gate current).

My arse !

Of course the low capacitance is a second order effect

You *have* to be kidding !

The gate power required to drive MOSFETs at modern switching frequencies is a
MAJOR consideration.

Why do you think certain semi makers make specialist gate drivers ! ?


Graham

 

[Terry Given]

Steve wrote:

Just wanted to post and thank everyone who helped out. We swapped the
transistors and removed to two 1k base limiting resistors and now the
circuit works perfectly...just like we wanted it to work.

Well done. Thanx for letting us know it worked

Cheers
Terry

 

[Jamie Morken]

Hi Steve,

steve wrote:

Jamie Morken <jmorken@shaw.ca> wrote in message news:<qYVid.100511$9b.21073@edtnps84>...


Is that board some type of navigation control for a model rocket? I
fly radio control planes, I couldn't find anything on the site that
talks about it.

It is a homebuilt inertial measurement unit using the Analog Devices
adxrs gyros and adxl accelerometers and a 16bit ADC, and an atmega32
with 4MB of datalogging flash.


Jamie,

Very nice homebuilt, I am wondering how did you solder the BGA device?
Oven? Or an pcb assembly shop?

Thanks! It was my first time working with BGA, I used a toaster oven
(works better than great!)

cheers,
Jamie

steve

cheers,
Jamie

 

[Kevin Aylward]

Pooh Bear wrote:

Kevin Aylward wrote:

Well, I am currently playing around with simulations of an audio amp
using state of the art bipolar (ft=50Mhz, 15A, 230V, 150W) and its a
no contest. Mosfets switch much faster. I can get 1000V/us (500W
@8ohms) with mosfets, only about 100V/us with bipolar.

And such slew rates are relevant to audio in *which* way ?

One-upmanship/specmanship. Its the challange dude.

Why do people Climb Mt. Everest?

Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.