HDTenEightyP/NetNews huggingface dataset:
From: cchapman@matd.gatech.edu (Charles H. Chapman)
Newsgroups: sci.electronics
Subject: Re: Isolated Connector for IEEE Bus?
Keywords: Advices sought
Date: 27 Aug 92 17:34:03 GMT
Organization: Georgia Institute of Technology

In article <4893@news.duke.edu> fang@phy.duke.edu (Fang Zhong) writes:
>From: fang@phy.duke.edu (Fang Zhong)
>Subject: Isolated Connector for IEEE Bus?
>Keywords: Advices sought
>Date: 27 Aug 92 02:07:36 GMT
>
>	I work on small signals of less than micro volts.  I use a computer
>to control my experiment and take data via IEEE bus.  One of the equipments
>in my setup is a digial ratio transformer made my Eaton Advanced Electronics.
>This equipment was designed so poorly that a ten-times larger noise was
>added to my circuit if I added it to my IEEE bus.  
>	I would like to find a way to add the digital ratiotran to the IEEE
>while the noise is isolated only to the ratiotran.
>	Will an optical isolation work in my case?
>

Hewlett Packard makes IEEE-488 bus extenders that have a fiber optic
option available.  You use a bus extender at each end of the fiber optic
cable (up to several miles in length I believe) to convert back to normal
IEEE-488 signals.

Chuck


Charles H. Chapman  (GTRI/MATD)             (404) 528-7588
Georgia Institute of Technology, Atlanta Georgia, 30332
uucp:     ...!{allegra,amd,hplabs,ut-ngp}!gatech!matd!cchapman
Internet: cchapman@matd.gatech.edu
From: agodwin@acorn.co.uk (Adrian Godwin)
Newsgroups: sci.electronics
Subject: Re: Success! Resist Pen Works in HP Plotter!
Keywords: resist pens, pcb, etching
Date: 1 Sep 92 13:27:43 GMT
Organization: Acorn Computers Ltd, Cambridge, UK

In article <78655@ut-emx.uucp> david@moe.ece.utexas.edu (david lee) writes:
>
>I admit that this is only a temporary solution, since not everyone has
>an HP 7470A plotter. The goal is to fill a drafting pen (which is intended
>for use with plotters) with a suitable resist ink. The following paragraph
>addresses the ink issue.
>

How about using the standard pen to draw on a photosensitive resist, which is
then developed and etched in the usual way ? It's more trouble than drawing
direct on the PCB, but it does avoid the problem of fitting an unsuitable pen
into a random plotter.

I'd like to go one further than David and avoid the need for chemicals 
altogether : machining the copper surface directly. The cutter would have
to be extremely small to do a useful job, but perhaps some sort of spark
erosion system might do it. 
Does anyone here have experience of spark erosion machines ? What sort of 
voltage and current is used, and how much material can reasonably be removed ?

-adrian

-- 
Adrian Godwin : agodwin@acorn.co.uk : adrian@fangorn.demon.co.uk : g7hwn@gb7khw
ObDisclaimer  : I believe this rubbish .. don't imagine that anyone else does.
From: u9dmlb@ohm.york.ac.uk (Duncan McL Barclay)
Newsgroups: sci.electronics
Subject: Re: Minimum speed on processors
Date: 27 Aug 92 20:18:44 GMT
Organization: Electronics Department, University of York, UK

In <1992Aug27.135703.26001@zip.eecs.umich.edu> johnwitt@cdrom.engin.umich.edu (John P Wittkoski ) writes:



>For a 33MHz 68030, there is a minimum clock speed listed for it in
>the databooks. I think it's somewhere around 25Mhz for a 33MHz version, but I
>don't have my databook handy.

>My question is: why is there a minimum?
>One possibility I have heard is that the on-chip registers and/or cache
>are dynamic in nature, and since the chip is geared for 33MHz, it divides
>this down to whatever rate is needed for the refresh circuitry. Therefore,
>if you go below the minimum, the refresh rate slows to below the minimum
>needed for the refresh.

Yup, you're about right. Sometimes the circuitry is a standard dymanic
RAM cell, othertimes slightly different. Apart from the minimun clock
speed required one can tell if the CPU is 'dynamic' by the single step
circuitry (usually shown in data sheets) the 68ks have a halt pin
or something similar to single step the processor. You maybe able to use
this as a bodge to get a slower processor, but you will still need to
satisfy the minimum clock requirement.

Incidently the Z80 was static so nice and easy to debug, just have a manual
clock.

>Now, is there someone out there who knows about this? I'm interested
>specifically in the 68xxx CPUs, but any general info would be helpful.
>For example:
>1. Is the guess I made above accurate, or is there some other reason?
>2. If the reason above is correct, does it apply to the registers, the
>   cache, or both (or neither?)
>3. If it's just a testing parameter, how far could I crank the clock speed
>   down? 20Mhz? 16,8,2,1???

> Just curious.

Well thats what makes this group intersting, discussions.

Raggy

-- 
Raggy                 | God smiles upon the little children, the alcoholics, and
u9dmlb@ohm.york.ac.uk | the permanantly stoned. S.King.
Newsgroups: sci.electronics
Subject: contacting N.O. Sokal, Design Automation Inc. 
From: mathiega@elec.canterbury.ac.nz (Grant A. Mathieson)
Date: 26 Aug 92 10:41:00 +1200
Distribution: world
Organization: Electrical Engineering, University of Canterbury, New Zealand
Keywords: Class E dc-dc conversion

Since reading a paper...

"Class-E Resonant Regulated DC/DC Power Converters: 
Analysis of Operation, and Experimental Results at 1.5 MHz"
Redl, R., Molnar, B., and Sokal, N.O., IEEE Power Electronics 
Specialists Conference 1983

...I have developed an interest in Class-E techniques for 
Power Conversion, which mimic those used in Class-E RF 
Power Amplifiers. 
Please share any knowledge you have about Class-E methods,
or how to contact any of the above Authors. In particular, 
Nathan O. Sokal, President Design Automation, Inc., 809 
Massachusetts Ave., Lexington, MA, USA. Ph (617) 862-8998 
(9 year old phone number). 
email me directly, if possible.
GAM
Grant A. Mathieson
From: karol+@pitt.edu (Filip Gieszczykiewicz)
Newsgroups: sci.electronics
Subject: Re: Supplier Wanted for Aircraft Mike Plugs (3/16")
Summary: solution?
Date: 2 Sep 92 05:53:58 GMT
Followup-To: sci.electronics
Organization: The Last Jedi

In article <1992Aug27.102217.8682@stc.nato.int> you write:
>Does anyone know where I can find a supplier for jack plugs and
>sockets for the microphone/push-to-talk of "standard" aircraft headsets?
>(By "standard", this includes David Clark headsets, at least!)

	Greetings. I've been there... I've looked and called
	all magazines & outlets and NONE have these. I ended up
	buying "push-to-talk" conversion kits and splicing
	in... not pretty but if done right (heat-shrink tubing,
	solder, strain-relief) it will work (as has my friend's
	which I made in '90 and sees about 4 hours/day use :-)

	If you DO find a source, I would be grateful if you
	could pass the info down - I don't feel like spending
	$39 per "kit" (that's plug, socket, & switch that mounts
	on the yoke). I've lately seen a few "mic cable extention"
	cables for (cheapest $14.95) - if you don't get better
	info this is the way to go. The sockets are the in-line
	type so I had to make a box for an array of 8 of them and
	then pot the box with epoxy (kinda permanent) so that they
	would stay in place. Works like a charm but I'd love a
	more "professional" construction :-)

	Take care.
-- 
________________________________________________________________________________
________________________________________________________________________________
_______________________karol@unix.cis.pitt.edu__________________________________
________________________________________________________________________________
From: johna@psdcae1.gvg.tek.com (John Abt)
Newsgroups: sci.electronics
Subject: Re: Filtering TV Commercials
Date: 4 Sep 92 15:04:20 GMT
Organization: Grass Valley Group, Grass Valley, CA


In <1992Sep03.042045.5095@ecst.csuchico.edu> rmintz@ecst.csuchico.edu (Rich Mintz) writes:
>I'm interested in building a device (or making my 386sx 
>act like one) that will be able to distinguish television 
>commercials from television programs. I've talked to a 
>few people and have heard of a couple of ways it is said 
>that this can be done.
 
>First, I was told that the audio during commercial 
>announcements on tv is boosted higher than that used for 
>normal programs (for obvious reasons). However, I've 
>tried all kinds of analysis with volume levels, averages 
>over specific periods of time, etc, using my computer's 
>sound card (with stereo capability), with no luck at 
>finding any dependable pattern to distinguish    ads from 
>shows.

There is no control of levels during commercial playback. However,
there are several factors that do make it seem like this is done.
The biggest one is that most program material, when leading  "into"
a commercial, has soft audio levels which trail off. Then the spot
starts, usually with full levels, and the effect is that it is louder.
Also, commercials are usually played-back from a different machine.
Whenever the "source" is switched, the level will change some. 
The machines which playback commercials often do have the levels
set high - but this is not a plot, it`s merely because the
operator doesn`t want any clients complaining about low levels.
Compression is used, but it tends to be significant only on the
obnoxious "shouting" type of spots (e.g., used car).

The bottom line is this: The broadcast TV industry makes its
money from commercials. If there were any reliable way of 
defeating that process, you can rest assured that it would be
fixed in rather short order.

Actually, something that would prove more useful, especially
given the upcomming presidential mud fest, is the bullshit filter.

John Abt
Newsgroups: sci.electronics
From: hbg6@phx.mcd.mot.com (John Schuch)
Subject: Re: Filtering wind noise
Organization: Motorola Computer Group, Tempe, Az.
Date: Mon, 31 Aug 1992 20:47:16 GMT

In article <1992Aug28.030426.6210@newsserver.rrzn.uni-hannover.de> riepe@ifwm11.ifw.uni-hannover.de (Michael Riepe) writes:
>In article <24875@castle.ed.ac.uk>, cam@castle.ed.ac.uk (Chris Malcolm) writes:
>|> In article <dfAW02=71de601@JUTS.ccc.amdahl.com> drp40@cd.amdahl.com writes:
>|> 
>|> >I'd like to be able to use two-way radios for skydiving.  Problem
>|> >is, 120mph of wind hitting up against a microphone would probably
>|> >mask out any voices.  Anyone have any ideas of how to get around
>|> >this?
>|> 
>|> 	1) A throat mike under clothing.
>|> 
>3) Use 2 mikes connected to a differential amplifier.


From the ad in this months "Mobile Radio Technology" magazine:


The Sonic Throat Microphone allows hands free communication in high
noise, severe enviroments. Police Special Operations and Fire Hazmat
Teams can maintain radio contact under adverse conditions.

Call or FAX for more information on Sonic Products

Sonic Communications, Inc.
4 Colonial Center Box 287
New Ipswitch, NH, 03071

(603) 878-1944
(603) 878-1773 (fax)


( I don't know them, I just saw the ad. )
John

Newsgroups: sci.electronics
From: johnh@macadam.mq.edu.au (John Haddy)
Subject: Project Design Time (repost)
Organization: Macquarie University, School of Mathematics, Physics, Computing and Electronics
Date: Sun, 30 Aug 1992 22:36:24 GMT

I suspect that the local news feed chewed up my last attempt to post this. If it
didn't then please forgive the second post!




I would like to ask for opinions on this issue:

How long, on average, would you consider a project design/construction to take?
i.e. how many man-weeks?

I refer to a project capable of being designed by one engineer and constructed by
two technical staff.

I know this is an open ended question, with not enough details to answer
precisely; but I'm after a "gut-feel", not a project plan. Projects are
non-trivial (trivial means a circuit that can be knocked up in under a week or
two with no worries) and require an engineer's skill (i.e. they're not the sort
that an experienced technician would be expected to handle), often with
background research required (e.g. magnetic properties of toroid materials, ECL
circuit design, high voltage electronics [10kV-20kV at several amps] etc).

Project design time in this case refers to:

1	Project specification
2	Design and schematic capture, with simulation and breadboarding where
		necessary
3	Printed circuit artwork design (on a CAD system)
4	Printed circuit fabrication, drilling and loading (assume in-house
		fabrication takes one day)
5	Circuit test and revision/modification
6	Chassis work (hole drilling, PC mounting, etc)
7	Front panel design and fabrication (Scotchcal or similar)
8	Final test and shipment ('out the door')

Also, how long would a repeat build take. That is, use an existing design. This
would be equivalent to steps 4..8 above, without the circuit revision or front
panel design elements.

My reason for asking is that a director here is under the impression that the
output of one engineer and two technicians here has been lower than it should.

Personally, I believe that their output has been beyond expectation. However, so
as not to bias your opinion, I'll not quote the details now.

I will summarise if there is enough interest.

John Haddy

----------------------------------------------------------------------------

      |  _  |_   _   |_|  _   _|  _|              Electronics Department
    |_| (_) | | | |  | | (_| (_| (_| \/           School of MPCE
    ---------------------------------/-           Macquarie University
                                                  Sydney, AUSTRALIA 2109

    Email: johnh@mpce.mq.edu.au, Ph: +61 2 805 8959, Fax: +61 2 805 8983

----------------------------------------------------------------------------
From: elliott@optilink.UUCP (Paul Elliott x225)
Newsgroups: sci.electronics
Subject: Re: 68HC705KICS - Worth of try?
Date: 26 Aug 92 18:39:52 GMT
Distribution: sci
Organization: DSC/Optilink Access Products

I, too was told that the Motorola development kit is no longer available
at any price.  I hope Moto changes their mind on that, or at least
releases the design and software so third parties can recreate it.
I would be willing to pay significantly more than $50 for it.

The chip itself looks usefull, but certainly very limited.  For the
price, it could easily become a "super-PAL", and replace lots of
random logic where speed isn't critical.  I am considering using
one to debounce, encode, and serialize a keypad for use with a
remote lock.  The limited program store and RAM will restrict 
applications, but there should be lots of jobs that this thing
will do nicely.


-- 
--------     Paul Elliott - DSC Optilink - Petaluma, CA USA      ----------
     {uunet,pyramid,tekbspa}!optilink!elliott -or- elliott@optilink.com
    "If I had known it was harmless I would have killed it myself." - PKD
From: jsevinsk@digi.lonestar.org (John Sevinsky)
Newsgroups: sci.electronics
Subject: Re: Rigging up a sound card so that it will do voice mail
Date: 28 Aug 92 19:26:02 GMT
Organization: DSC Communications Corp, Plano, TX

In article <1992Aug27.010101.13945@u.washington.edu> gunthar@milton.u.washington.edu (John Jacobson) writes:
>I am thinking about rigging up my computer so that it will :
>    - Determine whether an incoming call is voice or modem
>    - Channel it either to the modem  < or >
>    - Start up the computer to output a recorded message to the
>      <out> so that the caller would know to leave a message.
>    - open up a voice file for input and then record the message
>      to that file.
>    - Increment a message counter

If you look in a DAK catalog, the have (or used to have; it's an old catalog)
a board for your PC called a "PC Switchboard."  It has:

* A 999 box voice mail system
* A 9600 baud FAX machine
* A 2400 baud modem

This might be what you're thinking about.

John
Newsgroups: sci.electronics
From: eric@telebit.com (Eric Smith)
Subject: Re: Isolated Connector for IEEE Bus?
Organization: Telebit Corporation
Date: 28 Aug 92 15:27:21

>>On Thu, 27 Aug 1992 17:14:32 GMT, dvsg0223@uxa.cso.uiuc.edu (David Salamon) said:
> Before you try something like that, note that your problems are most likely
> due to a ground loop.  The IEEE bus has two ground lines, called "shield"
> and "digital ground".  They shouldn't be hooked together anywhere, and your
> instrument should not be using "shield" ground as its true ground.  Digital
> ground should be the only ground that is connected between machines.  The
> shield should be left unconnected unless you are sure all instruments have
> their cases hooked to the power line ground, in which case it is safe to hook
> shield to the instrument cases.

It seems to me that the shield ground of the cable(s) should be connected to
the fram ground of exactly one machine, or you could have ground loops.  

Also, the data (digital) ground should be connected to the true (power line)
ground in exactly one place, preferrably the same point as the cable shield.
Unfortunately this is hard to do, as most equipment ties the data ground to
the power line ground.

Cheers,
Eric
From: stuart@tellabs.com (Rick Stuart)
Newsgroups: sci.electronics
Subject: Comp monitor high voltage out (& Re: Computer monitor)
Keywords: monitor high voltage computer
Date: 27 Aug 92 17:46:44 GMT
Distribution: usa
Organization: Tellabs, Inc., IL
Originator: stuart@sunc19

In article <ssomaroo.714255819@unpcs1> ssomaroo@unpcs1.cs.unp.ac.za
(Shyamal Somaroo) writes:

>I used to own a Commodore 128 computer and had a monitor for it.
>Now I use the monitor as a television screen and wonder if it
>is possible for me to use it with my CGA card since I have a black
>and white screen at the moment.

Sounds like your Commodore monitor accepts composite signals, the CGA
card produces RGB signals.  To turn RGB into composite, you need to
build a modulator (Trivial if you have the parts and know-how, other
wise not worth it, *I* think.)  Besides, used CGA monitors should run
less than $100.

>Also if it is possible could I use it with a VGA card and if so
>how do I do it?

If you are using it as a TV monitor, it runs at about 15kHz.  VGA monitors
run at about 35kHz.  Trying to run your Commodore monitor at this speed
might shorten it's life to a few moments!

______________________
On to *my* question...

I have a Teknika CGA/EGA/PGA (almost VGA) multisync monitor (MJ-503).
The other night the high voltage died (or so I assume).  What advice do
*you* have for me.  I'm looking for feed-back like...

"Capacitors sitting between the fly-back primary and the power
transistor oscillator are the first to go."

                                ...or....

"Have you examined the case of the conversion diode between the
fly-back and anode of the picture tube?"

If the feed back is good, I'll collect and post them!

                                ...thanks, Rick Stuart
                                           Lisle, IL
Newsgroups: sci.electronics
From: sergeb@cco.caltech.edu (Serge J. Belongie)
Subject: Need phone line sp
Organization: California Institute of Technology, Pasadena
Date: Thu, 3 Sep 1992 19:13:24 GMT

Hello,
 
I need to know some of the specifications for phone line levels, namely:

Vac, Vdc for:	Phone Onhook
		Phone Offhook (dialtone)
		Phone Offhook (button pressed)
		Phone Onhook (ring incoming at ??hz)

I have made some rather crude measurements myself with a multimeter,
but they seem to change each time I measure them.  I tried checking
the CCITT standards ftp sites, but they seem to have all disappeared.
Any help with this information would be greatly appreciated.

Serge

Newsgroups: sci.electronics
From: kilian@cray.com (Alan Kilian)
Subject: MC68HC11 processor types and math
Organization: Cray Research, Inc.
Date: 31 Aug 92 13:59:39 CDT

O.K. Here's everything I know about different versions of MC68HC11s:
I think the MC68HC811A8 is the greatest, but I don't know what it costs.

+------------------------------------------------------------------------------+
| PART NUMBER | EPROM | ROM | EEPROM | RAM |  Comments                         |
+------------------------------------------------------------------------------+
| MC68HC11A8  |  ---  |  8K |   512  | 256 | Family built around this device   |
| MC68HC11A1  |  ---  | --- |   512  | 256 | 'A8 with ROM disabled             |
| MC68HC11A0  |  ---  | --- |   ---  | 256 | 'A8 with ROM and EEPROM disabled  |
| MC68HC811A8 |  ---  | --- | 8K+512 | 256 | EEPROM emulator for 'A8           |
| MC68HC11E9  |  ---  | 12K |   512  | 512 | 4 input capture, 512 ram, 12K ROM |
| MC68HC11E1  |  ---  | --- |   512  | 512 | 'E9 with ROM disabled             |
| MC68HC11E0  |  ---  | --- |   ---  | 512 | 'E9 with ROM and EEPROM disabled  |
| MC68HC811E2 |  ---  | --- |    2K  | 256 | No ROM part for expanded systems  |
| MC68HC711E9 |  12K  | --- |   512  | 512 | One-time programmable version 'E9 |
| MC68HC11D3  |  ---  |  4K |   ---  | 192 | Low cost 40-pin version           |
| MC68HC711D3 |   4K  | --- |   ---  | 192 | One-time programmable version 'D3 |
| MC68HC11F1  |  ---  | --- |   512  | 1K  | Non-multiplexed 68-Pin            |
| MC68HC11K4  |  ---  | 24K |   640  | 768 | >1Meg memory space PWM, CS, 84-Pin|
| MC68HC711K4 |  24K  | --- |   640  | 768 | One-time programmable version 'K4 |
| MC68HC11L6  |  ---  | 16K |   512  | 512 | Like the 'E9 more ROM, I/O 64/68  |
| MC68HC711L6 |  16K  | --- |   512  | 512 | One-time programmable version 'L4 |
+------------------------------------------------------------------------------+
Notes:
1) On the E2, and F1 parts the EEPROM is relocatable to the top of any 4K page.
   Relocation is done with the upper 4 bits of the CONFIG register.
2) I think the L6 part comes in 64 or 68 pin versions.
3) The E9 part only comes in 52 pin PLCC
4) The A8 comes in either 52 pin PLCC or 48 pin DIP. 
   On the 48 pin DIP version Port E bits 4,5,6,7 (Analog inputs 4,5,6,7) are
   not available. That's where they get the extra 4 pins from.
5) The suffix for 52 pin PLCC is "FN"
   The suffix for 48 pin DIP  is "P"
6) There are a million versions of all these. 2, 3, and 4 MHZ BUS speeds
   and a lot of other things. I have a "Motorola roadmap" that lists 36
   different suffixes.
7) There is an 'N4 version with 24K ROM, 768 RAM, 640 EEPROM, 8-bit A/D,
   8-bit D/A, 6 PWMs, 16 bit math co-processor, 62 bits of I/O and a 4MHZ
   non-multiplexed bus. Good luck finding this guy!
-- 
 -Alan Kilian           kilian@cray.com 612.683.5499 (Work) 612.729.1652 (Home)
  Cray Research, Inc.   655 F Lone Oak Drive, Eagan  MN, 55121 
                        "It's based on actual math". -Dilbert
Newsgroups: sci.electronics,alt.guitar
From: luthe@jach.hawaii.edu (Rusty Luthe)
Subject: Re: Building effects units for guitars
Reply-To: luthe@jach.hawaii.edu
Organization: UK/Canada/Netherlands Joint Astronomy Centre, Hilo, HI
Date: Fri, 4 Sep 1992 20:19:40 GMT

Hi,

Get the book Electronics Projects For Musicians by Craig Anderton. I've
built almost every circuit in there and not only do they work but are
very useful. Especially the Envelope Follower. That coupled to the
Phaser project are really nice. 
For those who were following the thread the Envelope Filter question
I would recommend reading Craigs discussion on the subject. Very
informative. Better yet build one and try it out yourself!
Gee I miss the days of build it yourself synths and guitar effects.
DSP technology has brought that all to an end, unless you are willing to
get into the nitty-gritty of DSP which is a very complex field and software
intensive.

Aloha,
Rusty