Driver to drive?

[Tony Williams]

In article <zyp0esd0odqo.dlg@news.individual.net>,
Active8 <reply2group@ndbbm.net> wrote:

530s weren't the thing to use. It was convienient
to drop the subckt in just to examine methods of controlling
things. Despite the potentially crappy model for this purpose,
I've demonstrated that I can control the idle current and the
offset. It's more effort at control than any MOSFET amps I've
found on the web. Notice there isn't much of that and even less
in the way of audio MOSPOWER parts. Seems like everything is
geared to class D now. Even the VMOS guides I found from the
'80's only touch on audio apps. The things just weren't designed
for that.

For HEXFETs it might be useful to consider a scheme
that biasses the MOSFETs at just below Vgs(threshold)
and have a Class A(B) driver stage with enough current
capability to supply the crossover load current itself.

Something that might even take advantage of the need
to bias the MOSFET Vgs at about 2V.


+------------+--- V+
+AC | |
| |/ |
+---|npn |
_|_ |\e |--+d
D1\_/ +--------||N
| | |--+s
| [R1] |
| | |
[R3] +------------+----[Rload]--- 0v
| | |
| [R2] |
_|_ | |--+s
D2\_/ +--------||P
| |/e |--+d
+---|pnp |
| |\ |
-AC | |
+------------+--- V-

The two transistors would be a TO-220 pnp/npn pair,
dissipating about 5-10W?, so mounted on the heatsink.

R1/R2 would be a relatively low value, say 50 ohms as
a first guess, with about 2V across each. So R3 would
be about 1k, with 4mA bias current through it.

The bipolar AC drive assumes active pull up/down
driving, as per the recent thread(s) on taking the
outputs from the supply rails of an opamp.

--
Tony Williams.

 

[xray]

On Mon, 27 Dec 2004 12:08:56 GMT, "Clarence_A" <no@No.com> wrote:

Had nothing to add

 

[Clarence_A]

"xray" <notreally@hotmail.invalid> wrote in message
news520t0du4c22th0gfl70vtamqovi5ordku@4ax.com...

On Mon, 27 Dec 2004 12:08:56 GMT, "Clarence_A" <no@No.com> wrote:

Had nothing to add

See? Your learning.

BTW: "PLONK!"

Just like Kevin Aylward.

 

[Leon Heller]

Jim Douglas wrote:

I am looking for something basic to use at home for small projects. I have
downloaded a few examples, PCB Wizard I like, Eagle Layout Editor seems too
much. Has anyone used the PCB Wizard product? Any other recommendations?

I am also using the student version of CircuitMaker, which is GREAT! I
understand at one time it had with it a product "TraxMaker"? but sure can't
find it in the version I have?

Have a look at Easy-PC: http://www.numberone.com

Leon

 

[Winfield Hill]

xray wrote...

Winfield Hill wrote:

I think the stuff that changes over time should be put on line.
e.g. the list of preferred commonly used parts.

That's a good idea, but it assumes we'll keep it up to date. <sigh

If there came to be an AOE web page, there could be a forum for these
kinds of questions and ideas categorized to some (evolving) extent.
Might be a FAQ or file section which tracks (among other things) the
suggestions for current nifty parts.

We have created AoE web pages, http://www.artofelectronics.com
but they doesn't have a user-comment engine. Just an email address,
which points to my mailbox at work. We do keep and use the comments
and suggestions which arrive there. And I try to answer most email.

[ snip good web-page suggestions... ]

Ok, enough propositions. It would be great to see something like
this evolve around AoE.

It would, do you have a suggestion for forum software?


--
Thanks,
- Win

 

[RST Engineering (jw)]

You've got it, and many thanks for your help. BTW, how do you like
Easy-PC. I hate to throw away six years of building a library for
Circuitmaker, but it looks like Protel is doing their best to kill the
sucker off.

If I hadn't been a beta tester for Microcode back in the old days and been
given a free production copy, I sure as hell wouldn't have purchased that
piece of trash.

Jim

I've got the latest version of Easy-PC. I'll generate the Gerbers for you
if you email them to me.

Leon
--
Leon Heller, G1HSM
leon.heller@dsl.pipex.com

 

[John Larkin]

On 24 Dec 2004 19:19:08 GMT, Ian Stirling <root@mauve.demon.co.uk>
wrote:

John Larkin <john@spamless.usa> wrote:
On Fri, 24 Dec 2004 07:07:05 GMT, Scott Stephens <scottxs@comcast.net
wrote:



And what method will the aristocracy employ to correct my deviant
thought?

The cruelest and most effective: they will ignore you.

Those who the gods would destroy, they first make mad.

Unless they were neurotic loonies already.

John

 

[Don Lancaster]

John Perry wrote:

Michael Black wrote:


...
Cookbook with 1974 copyright. Even better, he used the concept in his
Psych-Tone in the February 1971 issue of Popular Electronics, page 25,
to generate random musical tones. (But I see nothing in his RTL Cookbookb
from 1969)

My copy of S. W. Golomb's _Shift_Register_Sequences_ is copyright 1967, and
his reference list goes back to 1801 (abstract algebraic theoretical
underpinnings), with obviously applicable references to 1953.

I happened upon Golomb's book while researching background material on that
same HP Journal article (for other purposes), which described a
pseudorandom-modulated probe signal that increased the range and accuracy
of one of their time-lapse-detection fiber optic test equipments.

I, too, seem to have lost the original hpj article and all direct references
to it.

--
j point e point perry at
cox point net

The original source for the pseudorandom sequences used in the TTL and
CMOS cookbooks and the psyctone was E.J Watson's listing in Mathematical
Computing 16, 1962 pages 368-369.

I thought everyone knew that.

The PsycTone came about at Goodyear Aerospace when a cubical mate was
applying these sequences to a multi-million dollar aerospace project and
I told him I thought I could make them squawk.

See http://www.tinaja.com/glib/atg1.pdf


--
Many thanks,

Don Lancaster
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
voice: (928)428-4073 email: don@tinaja.com

Please visit my GURU's LAIR web site at http://www.tinaja.com

 

[David Harmon]

On Mon, 27 Dec 2004 11:44:12 -0700 in sci.electronics.design, Don
Lancaster <don@tinaja.com> wrote,

The original source for the pseudorandom sequences used in the TTL and
CMOS cookbooks and the psyctone was E.J Watson's listing in Mathematical
Computing 16, 1962 pages 368-369.

I thought everyone knew that.

My copies of the TTL and CMOS cookbooks appear to be the editions
without the bibliography.

 

[Rich Grise]

On Sun, 26 Dec 2004 23:12:26 -0700, hamilton wrote:
....

The next thing to look at is the voltage drop across each LED.
If you bought the LEDs from R.S., then on the back of the package will
be the voltage and current rating for that LED.

Most LEDs are about 2.0 volts each. ( more or less, check the packaging )

At 12.0 volts, 6 LEDs can be strung together with out damaging them.

Only if you are very, very lucky.

Do not attempt to drive LEDs with a constant-voltage source, without
a current limiting resistor. In this case, if we take battery voltage
as a nominal 13.6, then that's 1.6 V you have to drop, at 20 mA is
1.6/.02 = 80 ohms. So 82 ohms, 1/4 watt will work, but at 14.2V,
you'll have 27 mA. So go for 20 mA at 14.6V (this is how high the
voltage gets when it's charging), you want 14.6-12, 2.6/.02= 130R;
RS has a 100 and a 220, so two 220s in parallel will give you 110R;
2.6/110=23.6 mA, so you should be OK.

If however your supply goes to 13.6 volts, some of the LEDs may get
damaged. ( burn out ) Maybe not right away, but one may burnout and then
the whole string will go out.

With no current limit, you are guaranteed to destroy LEDs.

Also, if the LEDs are going to be in fixed positions relative to your
holes, just do one board and line them up right.

Good Luck!
Rich

 

[Winfield Hill]

Fritz Schlunder wrote...

Have you tried hanging one or more extra LC low pass filter(s) on the
output of the DC/DC converter modules? In my experience playing with
DC/DC converters this extra LC filter can sometimes greatly improve
at least the aesthetic appearance of the output voltage as viewed on
an oscilloscope.

Indeed, it's not too hard to get the switching-converter output noise
voltage basically down to zero, when measured across that last filter
capacitor with a good probing system. But a short distance away,
where used, the noise may well be high again, due to several causes.
One is noisy ground currents. Another is noisy magnetic fields.
Either can be a killer and can be VERY hard to completely eliminate.

Are you familiar with and have addressed the other considerations
when using high resolution AD converters?

http://ww1.microchip.com/downloads/en/AppNotes/00688b.pdf

A nice reference.


--
Thanks,
- Win

 

[John Larkin]

On Mon, 27 Dec 2004 21:09:33 GMT, Rich Grise <richgrise@example.net>
wrote:

A lot of people say "use a pic." If you're using a stepper motor, and
want to index to 0, don't use a hall sensor. Use an optical interruptor
with a narrow slot; you don't have to mess with analog thresholds and
signals buried in noise and stuff.

Or even a reed switch.

Or just a hard stop. At powerup, run the stepper enough steps to
guarantee running up against the stop, then you know where you are.
You can either just stall the motor (no harm done) or slip a coupling
of some sort (belleville washer junction or whatever) if you prefer.

John

 

[Rich Grise]

On Sat, 25 Dec 2004 15:55:11 -0800, John Larkin wrote:

On Sat, 25 Dec 2004 23:25:10 +0000, John Woodgate
jmw@jmwa.demon.contraspam.yuk> wrote:


Darwinian evolution **works**. Unresolved questions are whether it is
the only type of evolution on Earth (or the only possible type anywhere)
and how it worked in specific detailed cases. Or didn't work, e.g. why
there are no animals with wheels.


If paved roads occurred naturally, there would be.

I've read that there are actually wheel-like structures - notably,

some little protein that spins and unwinds the double-helix for
mitosis. But that's not really an animal with wheels. )-;

Cheers!
Rich

 

[Guy Macon]

Rich Grise wrote:

Don't mail it to an accomplice. Mail it to a notary, and ask them to
record the date and stamp it, then come to the show.

Even better!

Rig the boombox so that when the accomplice puts the tape into
the boom box and hits "play", it does the magic - you don't need
to touch anything. Of course, you have to play it all the way
through, and then _not_ do the magic again, i.e. "Play" now
means "play".

Yup. That's what I wrote. The secret sequence is to arm it again
before the next show.

 

[RST Engineering (jw)]

I think I may have you beat. My original DOS copy was on a 5" floppy and
the label on the disk itself was done with a dot matrix printer. I don't
remember whether or not I kept either the serial or my customer number, as I
was NOT particularly impressed with Dos version 1.0 or whatever it was.

Jim


"Leon Heller" <leon.heller@dsl.pipex.com> wrote in message
news:41d06eca$0$16572$cc9e4d1f@news-text.dial.pipex.com...

I used Easy-PC for years from when it first came out (Customer Number
13114). WestDev bought Number One when it eventually went bust, noticed
that I was the longest-serving original customer and asked me if I would
be interested in beta-testing their new Pulsonix software. They recently
gave me a copy of the latest Easy-PC V8 to try out and I was quite
impressed with it. I much prefer Pulsonix, of course.

Leon

 

[ssparling]

Try using Electronics Workbench, Iuse it to test all my projects.
L8TR,
Mod

 

[James Meyer]

On 27 Dec 2004 22:15:16 -0800, jkeagle13@aol.com wroth:

I was told by a specialist per these specifications that we needed
a 50hp phase converter. If anyone has a spare they can donate or knows
of a possibility for a donation, or can point us in the right
direction, or has any other helpful information for the project we
would deeply appreciate every little thing we can get at this point!

---- assuming that the original poster will come back to read replies ---

The government should have plenty of surplus mobile generators
available. You know, the ones that have diesel engines and can be towed around
behind a big truck. I'll bet you could arrange to "borrow" one of those with
suitable output power specifications to allow you to connect directly to your
sirens for free.

Jim

 

[Dbowey]

Jon Yaeger posted:

(big snip)

<< Aristotle understood the universe.

Ptolomy understood the universe.

Plato understood the universe.

Da Vinci understood the universe.

Newton understood the universe.

Einstein understood the universe.

Get my point? >>

--

Maybe. By omission, you mean you and Hawking don't?

 

[Frithiof Andreas Jensen]

"martin griffith" <martingriffith@yahoo.co.uk> skrev i en meddelelse
news:289js05155e8vh020ukn1npej0tvqn9lgt@4ax.com...

On 22 Dec 2004 08:29:28 -0800, in sci.electronics.design
..
I wonder what they send bck to china in the containers? I cant imagine
the chinese need much from the EU or US

Paint, for example ;-)

Used Car Tires is another: People pay here to get their tires taken away,
the Chinese pay to get the worn tires - as long as they are round and hold
air, they are Fine!

Scrap Metal, Plastics, and whatever other Junk it does not pay to recycle
here (or costs too much in disposal tax).

Off it goes.

 

[Jon Yaeger]

in article 20041228100042.08096.00002490@mb-m07.aol.com, Dbowey at
dbowey@aol.com wrote on 12/28/04 10:00 AM:

Jon Yaeger posted:

(big snip)

Aristotle understood the universe.

Ptolomy understood the universe.

Plato understood the universe.

Da Vinci understood the universe.

Newton understood the universe.

Einstein understood the universe.

Get my point?

--

Maybe. By omission, you mean you and Hawking don't?

I certainly don't! Hawking speaks for himself.

;-)