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'[EE] Wire wrapping insight needed!'
2005\03\05@212302 by Senior Design

picon face
Hi all,

My senior project design team is about to build a wire-wrapped
prototype of our final project. I was hoping that some of you may lend
a few [much needed] words of advice. Here's some general background
information:

0. We've never wire wrapped anything before...
1. We'll be using a PIC demo board (the 64/80-pin PIC18F8XX20 board)
at 20MHz to drive control signals for now... and the PIC by itself
only later when it's PCB time.
2. We'll be using a perforated board with 2-sided copper planes.
3. We've purchased solid AWG 30 twisted pair wire for wrapping.
4. We have a simple Radio Shack manual wire wrapping tool.

I'm obviously making implications with these statements -- i.e., that
we plan on using a power and ground plane, effectively shielding our
[very thin] signal wire using the twisted pair ground-ground concept,
etc. However, please don't take anything for granted. We don't really
know what we're doing :)

Any and all suggestions will very much be appreciated... wire sizes,
distances, power and ground methodologies, preserving clock integrity,
etc. I want to be able to do this right the first time, and I need a
lot of help from all of you experienced engineers.

Thanks so much!
Julian

2005\03\05@221701 by Bob Axtell

face picon face
I once did all my breadboarding in wire-wrap wire... but

Wirewrapping is no longer very popular as a way to breadboard stuff, because
it adds inductance and capaitance in the wiring over and above what other
breadboard techniques use. In fact, it is about 50% cheaper to simply layout
the design and commit a PCB layout without silkscreen or solder mask.

BUT.. if you are committed:

1. Use 30-guage Silver-plated Kynar wire. Use a commercial wirewrap gun and
purchase the correct wire-wrap bit for the guage.

2. Purchase unwrap tools. Its very difficult to remove wires placed in
error unless
these are used.

3. When making power and GND connections, use extremely short wires and
solder then when wrapped, to keep the connection resistance as low as
possible.

4. When making a signal connection, make the route as straight a path as
possible.,
Resist the natural tendency to neatly lace everything. Then you lace,
the wires cross-
couple and can cause some strange effects.

Have fun!

--Bob Axtell

Senior Design wrote:

{Quote hidden}

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2005\03\05@225514 by Herbert Graf

flavicon
face
On Sat, 2005-03-05 at 21:23 -0500, Senior Design wrote:
> Hi all,
>
> My senior project design team is about to build a wire-wrapped
> prototype of our final project. I was hoping that some of you may lend
> a few [much needed] words of advice. Here's some general background
> information:

In my fourth year I had an analog course where we had to hand build
something out of discrete MOS transistors. This "something" had to be a
significant building block on an analog IC, so something like an Op amp
or current mirror alone wouldn't be enough. I built an ADC (four bit,
successive approximation, worked quite well, to save on number of gates
I built my latches out of transmission gates, but I digress...).

Anyways, we were told that we were NOT permitted to use a breadboard, it
must be built using either wire-wrap or soldered together, with
soldering being a STRONG recommendation over wir-ewrap.

Some students choose the wire-wrap method, and they wasted ALOT of time
getting their circuits to work at all.

So, with all that said, MUST you use the wire-wrap technique? There are
MANY reasons soldering is a FAR better idea, especially if you have alot
of connections to make.

TTYL

-----------------------------
Herbert's PIC Stuff:
http://repatch.dyndns.org:8383/pic_stuff/

2005\03\06@000455 by William C. Wilson, Jr.

flavicon
face

> Hi all,
>
> My senior project design team is about to build a wire-wrapped
> prototype of our final project. I was hoping that some of you may lend
> a few [much needed] words of advice. Here's some general background
> information:

Along with keeping signal lines as straight as possible, power lines
as short as possible, and soldering the power lines...

You will probably be using some wire wrap sockets for your chips.
It is often helpful to superglue the sockets to the board so they
don't move around on you while you get them wrapped. If you can't
use superglue or don't want to use it, then just lightly wirewrap
the 4 corners of the socket first, make all of the other connections,
and then undo the corners and do those connections.

6 to 8 turns around a wirewrap post is the usual number of turns
to take to ensure a tight connection.

Since you are new to wirewrapping, you might want to practice a
little while on some scrap posts or wire before you actually do
it on your circuit. Practice will teach you what not to do.

I usually get the colored 30 gauge Kynar wire. That way I can
use one color for signals, one color for ground, etc. I always
connect my grounds first and then the other power lines. This
prevents me from connecting the chip up backwards later on.

If you goof up and have to unwrap a connection do not reuse that
piece of wire.

A small pair of wiresnips or manicure scissors are nice to have around
to trim up the extra bit of wire on the posts.

Good luck
--
Cris Wilson
Clemson University
Daniel 212
.....crisKILLspamspam@spam@clemson.edu

2005\03\06@063958 by Lee Jones

flavicon
face
>> My senior project design team is about to build a wire-wrapped
>> prototype of our final project. I was hoping that some of you may lend
>> a few [much needed] words of advice. Here's some general background
>> information:

I distributed power & ground lines using larger gage wire.  A
great source of 24 gage wire is scrap UTP network cable.  And it
automatically comes in 8 distinct color patterns.  After stripping
end, wrap bare wire around pin (physical strength), then solder it.


> You will probably be using some wire wrap sockets for your chips.
> It is often helpful to superglue the sockets to the board

Agreed.  I used epoxy.  Trying to wirewrap to pins on a socket
that's moving all over the place is difficult & very frustrating.


> Since you are new to wirewrapping, you might want to practice a
> little while on some scrap posts or wire before you actually do
> it on your circuit. Practice will teach you what not to do.

Definitely practice.  Turns of wirewrap wire must be adjacent to
each other on the pin -- no space between turns and don't let the
wirewrap wire overlay a previous turn.  Either a loose wrap or a
bunched wrap (wire in 2 or more layers on pin) is cause to rip up
and redo that wire segment.  The sharp edge of the pin has to bite
into the wirewrap wire to make a gas tight bond.

This skill takes a while to learn using a manual tool (the kind
that you twist with your finger tips).  Twisting while putting
just the right amount of down-force is hard to "get".  A power
wrapping tool usually has a spring-loaded bit that makes this
easier.  Not easy... but easier to get right.  It does take a
while to learn the "feel" with either tool.

You do need a hand tools though.  One end is for wrapping (which
you don't use), one end is for unwrapping (which you WILL use),
and usually has a wire stripper designed specifically for 30 gage
kynar coated wire in the middle.  That stripper alone is reason
to have the manual tool.


> I usually get the colored 30 gauge Kynar wire.

You used to be able to get kits of various lengths of wire with
both ends pre-stripped.  Stripping the ends of each piece of wire
will consume vaste amounts of your time; buy the pre-stripped.
Then you just have to strip a few ends of those few really long
runs of wire that every circuit has. :-)

With pre-cut & pre-stripped wire assortments, you get really good
pretty quickly at looking at your board and "knowing" what length
of wire you need for that next wrap.  And it seems like there is
_always_ another wrap to do while you are building the board.


> If you goof up and have to unwrap a connection do not reuse that
> piece of wire.

Right.  A wirewrap wire can be used once & only once.  (If you
screw up a long wire, you can restrip the end(s) and reuse it.
But it's usually not worth it.)


> A small pair of wiresnips or manicure scissors are nice to have
> around to trim up the extra bit of wire on the posts.

Properly done, all the bare wire will be tightly wrapped around
the pin.  I used the "modified wrap" where you wrapped ~1 turn of
the insulated wire (before the bare wire) around the pin to improve
physical strength of the joint.


Don't daisy chain.  What I mean by that is ... if you are sending
a signal to many pins, like a clock, do not wire from pin A to pin
B (1st wire), then pin B to pin C (2nd wire), then pin C to pin D
(3rd wire), etc.  If you find you made a mistake on pin B, you have
to remove EVERY wire past that point in your rework.

Instead alternate in 2 layers: (1st layer) wire from pin A to pin B,
pin C to pin D, pin E to pin F, then (2nd layer) pin B to pin C,
pin D to pin E, etc.  This lets you replace any wire in that path
and never have to rip up & redo more than 2 other wires.


One trick I used to try & keep from forgetting wires.  Every time
you finish wrapping both ends of a wire on your board, highlight
that path segment on your schematic.  When all the lines on the
schematic are highlighted, you are done.  Never highlight before
wrapping; always highlight afterwards.  Failure mode (forgot to
hightlight a line) means you'll double check a wire segment and
find it's already in place.  A missing wire can be hard to find.


Given the current cost of prototype PC boards, you really should
look into it as an alternative to wirewrapping.

                                               Lee Jones

2005\03\06@090841 by Senior Design

picon face
Thanks for your all of your replies thus far.

To address some common points...

Yes, I do indeed have to wirewrap. What I'm _not_ going to pursue is a
breadboarded prototype. The idea is that we want to get a PCB built,
but if it fails or we run out of time, etc., we can use our prototype
-- and while breadboards are not acceptable, wire-wrapped designs are.
So, with that said:

It was recommended that perhaps I solder instead of wirewrap. And, I
[sort of] can do that. I will be using wire-wrapped sockets to solder
discrete components in place, with tiny (0.5") wires wrapped from the
pins of the ICs' adaptors to the appropriate socket's pin. I believe
this is the best method of "placing" discrete components. Please
correct me if I'm wrong.

For power and ground, I will be using the common ground plane and
power planes on either side of the perforated board. I want to use
larger wire (AWG 14 or so) to solder a _very_ short (< 0.5") wire from
the appropriate IC pin to the plane. Again, if this is the wrong
method, please let me know.

Finally, does anyone have advice on clock integrity? I have to
distribute a 15MHz clock to a few points, and I'm afraid I'll lose it.
Should I place some resistance at the driver (30 Ohms or less)? And
what length must I keep this to?

Finally, I've heard that using 30 gauge, solid twisted pair wire is
the best bet, because one wire can connect pin to pin while its
twisted pair can connect ground plane to ground plane at similar
points, thus shielding the wire over its distance. Is this a generally
safe method of preserving signal integrity at ~ 20MHz?

Thanks again, everyone. I appreciate your help.

Julian

2005\03\06@125042 by Dave VanHorn

flavicon
face

>
>You will probably be using some wire wrap sockets for your chips.
>It is often helpful to superglue the sockets to the board so they
>don't move around on you while you get them wrapped. If you can't
>use superglue or don't want to use it, then just lightly wirewrap
>the 4 corners of the socket first, make all of the other connections,
>and then undo the corners and do those connections.

When I did WW, I did power and ground distribution first, with decoupling
caps, and I soldered the power pins to the vectorboard.  Then everything
else in different colors according to function, and what wire colors I had
on hand.
Absolutely don't bundle.  This is one case where "neat" is BAD.


2005\03\06@150221 by olin_piclist

face picon face
Senior Design wrote:
> 0. We've never wire wrapped anything before...

I would keep it that way.  Wire wrapping is something dinasours did.  In
recent years the price of small quantity PC board fabrication has come done
dramatically.  Some places even have student discounts.  If you can stick to
2 layers, then you should be able to get 4-5 boards of reasonable size of
under $100.  It will be more work to do your first PC board than to wire
wrap one, but it is a much more valuable skill.  It won't be nearly as
intimidating the second time.

It will also sound a lot better in an interview if you said you made PC
boards for your senior project rather than wire wrapped it.  If someone came
to me out of school and talked about their senior project being wire
wrapped, I would immediately think the professor hasn't kept up, and wonder
what else you didn't learn.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\03\06@171428 by Bob Axtell

face picon face
Senior Design wrote:

<respectful snip>

{Quote hidden}

These speeds are really out of the wirewrap realm. I think you will have
trouble
unless you terminate the ends of the wire to reduce ringing and crosstalk.

I'm sorry we weren't very supportive, but most of us have  wirewrapped some
and have gotten past it. It's just no longer "state of the art".

--Bob

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2005\03\06@215154 by Herbert Graf

flavicon
face
On Sun, 2005-03-06 at 09:08 -0500, Senior Design wrote:
> Finally, does anyone have advice on clock integrity? I have to
> distribute a 15MHz clock to a few points, and I'm afraid I'll lose it.

15MHz? Unless you are REALLY familiar with wire-wrapping I would stop
right there, 15MHz opens you up to allot of "fun" with wire wrapping
that you shouldn't waste your time with (even more so if you have ANY
analog in your system, thing of all those wire wrap wires cris-crossing
as wonderful points of noise being injected to other parts of the
circuit).

At 15MHz I would, AT LEAST, solder things together, but even that would
make me a little wary (especially if you have quite a few chips).

At 15MHz I would STRONGLY suggest using a PCB, making one is quite easy,
even for a beginner, and you will be fighting far fewer gremlins with a
well designed PCB then you would with any sort of wire wrapping. TTYL


-----------------------------
Herbert's PIC Stuff:
http://repatch.dyndns.org:8383/pic_stuff/

2005\03\06@215620 by Bob Axtell

face picon face
Herbert Graf wrote:

{Quote hidden}

I don't recall ANY of my stuff working on a WW breadboard above
4.9152Mhz ....

--Bob

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2005\03\06@215657 by Jake Brownson

picon face
Wow, I don't know why everybody is complaining about WWing. In my
Junior level microprocessors I just completed, and in my PLDs class
Sophomore year we did _plenty_ of wire wrapping. It is much easier
than soldering everything, and though we ran fairly slow clocks
(16MHz) there were never concerns with EMI or anything, though we did
discuss that at faster speeds there might be some. All you need for
wire wrapping is the $7 wire wrapping tool from Radio Shack, some
wire, and some posts, don't waste your money on some fancy electric
wrapper or a separate removal tool. A good stripper (not that kind) is
handy, but I used the little one that comes w/ the WW tool for 3 terms
with no problem.

As some have said already, but I'll confirm:
* Probably don't use 30 AWG wire for your power lines
* Keep high frequency/noisy lines far away from the sensitive ones, and short
* If you need a long HF line or one close to other wires, try to run
it perpendicular to other wires
* You can spend 10 mins practicing and be just fine

If I were going to make a relatively complicated design
(connection-wise anyway) I would most likely choose wirewrapping for
prototyping, and then develop a PCB for it when I knew it was working,
but a carefully wirewrapped board is perfectly presentable, and
debuggable.

As for the speed concerns, try an experiment with a 40MHz freq
generator going to a post, and hook up an osc to a loose wire or
something, and see how much EMI you get.

(I'm no expert w/ EMI and HS problems, so listen to someone else on
that if they know better)

~Jake B

2005\03\06@220312 by Bob Axtell

face picon face
Jake Brownson wrote:

{Quote hidden}

Mr Design, go for it. Us 'ole guys have been proven wrong before... I am not
afraid of being proven wrong...I can take it. I'm from Arizona (I don't
shave,
I have a tiny hammer- I pound 'em in and bite 'em off from the inside).

<G>

--Bob Axtell

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2005\03\06@222804 by Jake Brownson

picon face
> Mr Design, go for it. Us 'ole guys have been proven wrong before... I am not
> afraid of being proven wrong...I can take it.

So what do you "ole guys" use for prototyping? Just solder everything?
Or is there some other technique I don't know about? I have done a few
prototypes with soldering too, and found it to be very messy, and if
there was a problem I always had to go back and double check my solder
joints in addition to everything else. With WWing I have never had a
problem due to a faulty connection (forgotten ones yes, but that's
another story). There's no hot iron to worry about burning yourself or
others with, if you remove a connection there's no leftover solder,
and I was able to wire much more quickly with WW than soldering, but
maybe that's just lack of skill with an iron. Oh and is it just me or
does soldering require 3 hands most of the time? One to hold the
solder, one for the iron, and one to hold the wire.

For small tests or playing around I do like breadboards. I have yet to
make a PCB, but I'll be taking a PCB class here sometime, and I'm have
a project going for which I plan on eventually making a PCB for, so
we'll see how that works out, but I can't imagine ordering a PCB w/o
hooking up the circuit some other way first.

Always enjoy learning new things,
Thanks :)

~Jake B

2005\03\06@230019 by Robert Rolf

picon face
An important part of a successful WW project is the
layout. THINK about what kind, and where your signals
are running. Think about signal flow, and lay out the chips to
minimize wiring length between them.
Keep the high frequency clock and associated
circuits close together so the signal runs are short.
Use star grounds to the clock driver(s) so that inductance
and ground bounce is minimized. Bypass EVERYTHING with
good quality caps. You'll save yourself a lot of grief
in the long run.

Build up the circuit in sections, if possible, and
test for correct performance as you go.
e.g. clock divider chains.

I built a 24 x 80 character video terminal in the mid 70's
using ww. 14.31818 MHz clock and no problems because the
high frequency circuits were laid out appropriately.

In the late 70's the CBC television broadcast delay
center was run entirely on racks worth of wire wrapped
combinatorial logic so it CAN be made reliably.

And don't forget the very speedy PDP 8 series of computers
the were entirely wire wrapped backplanes and controllers.
Async clocks at more than 2 MHz.

Robert

Jake Brownson wrote:

{Quote hidden}

2005\03\06@230331 by Mark Rages

face picon face
On Sun, 6 Mar 2005 19:28:04 -0800, Jake Brownson <jbrownsonspamspam_OUTgmail.com> wrote:
> > Mr Design, go for it. Us 'ole guys have been proven wrong before... I am not
> > afraid of being proven wrong...I can take it.
>
> So what do you "ole guys" use for prototyping? Just solder everything?
> Or is there some other technique I don't know about?

This 'ole guy' just double-checks the design, crosses his fingers and
sends a PCB out to fab...  especially for developing a commercial
product which is gonna be PCB anyway.  If you get lucky, you'll be 95%
right, and some work with an x-acto knife and soldering iron will get
your prototype working.  Then make a rev B board and you're in
business.

The first PCB you design takes forever.  After you've learned the
software it's not bad at all.

What is your time worth?  Does your design have any parts that only
come in SMT packages?

Regards,
Mark
markrages@gmail
--
You think that it is a secret, but it never has been one.
 - fortune cookie

2005\03\06@235821 by Herbert Graf

flavicon
face
On Sun, 2005-03-06 at 19:28 -0800, Jake Brownson wrote:
> > Mr Design, go for it. Us 'ole guys have been proven wrong before... I am not
> > afraid of being proven wrong...I can take it.
>
> So what do you "ole guys" use for prototyping?

Certainly not an "ole guy" but most of my prototyping has been
soldering, usually using a type of "breadboard" type PCB.

For more critical work I've actually just created a custom PCB, for some
designs (where most of the dirty work is software) a PCB can be faster
then any other method (provided you do put in SOME room for modding
things).

> Just solder everything?
> Or is there some other technique I don't know about? I have done a few
> prototypes with soldering too, and found it to be very messy, and if
> there was a problem I always had to go back and double check my solder
> joints in addition to everything else.

I'm sorry, but I haven't had to "double check" my solder joints for
quite a while. I'd say if you got more practise soldering you wouldn't
have to either. Soldering, if you're experienced, is very reliable.

> With WWing I have never had a
> problem due to a faulty connection (forgotten ones yes, but that's
> another story). There's no hot iron to worry about burning yourself or
> others with,

If you can't be careful with an iron I don't know what to say...

> if you remove a connection there's no leftover solder,

Solder wick, very quick to use, I can probably disconnect and clean up a
joint in as fast a time as it takes you to remove a wire-wrapped
connection (and I'm even faster if we're sticking to through hole
stuff...)

> and I was able to wire much more quickly with WW than soldering, but
> maybe that's just lack of skill with an iron. Oh and is it just me or
> does soldering require 3 hands most of the time? One to hold the
> solder, one for the iron, and one to hold the wire.

It does simply sound like lack of experience with the iron. And no,
three hands are rarely needed. About the only time I haven't figured out
a way to get away with only two hands is soldering wires onto DB9, that
first wire always needs my pair of vise grips... after the first wire
I'm OK though.

> For small tests or playing around I do like breadboards. I have yet to
> make a PCB, but I'll be taking a PCB class here sometime, and I'm have
> a project going for which I plan on eventually making a PCB for, so
> we'll see how that works out, but I can't imagine ordering a PCB w/o
> hooking up the circuit some other way first.

Breadboards in my experience can often times be more trouble then
they're worth. I've bumped into quite a few bugs in the past due to
breadboards (mostly coupling and capacitive loading issues, some cross
talk problems too, along with power issues). I do almost all my
prototyping with solder breadboards, PCBs with patterns already etched
and holes already drilled, just a matter of soldering the parts in, and
the odd wire to connect things together.

> Always enjoy learning new things,
> Thanks :)

TTYL


-----------------------------
Herbert's PIC Stuff:
http://repatch.dyndns.org:8383/pic_stuff/

2005\03\07@034250 by William Chops Westfield

face picon face

On Mar 6, 2005, at 7:28 PM, Jake Brownson wrote:

>> Mr Design, go for it. Us 'ole guys have been proven wrong before...
>> I am not afraid of being proven wrong...I can take it.
>
> So what do you "ole guys" use for prototyping?

PCBs.  At $100 or less for a prototype board (actually, several
boards) and less than a week turnaround, WW doesn't make sense.
And that's supposing you don't make your own PCB.  (do you know
how little engineering time, or even technician time, you can
buy for $100?)  (At some professional engineering level, the prototype
boards have fine pitch packages and 12 layers, and the need to
use a PCB for the prototype as well as production is "obvious."
The point is that it makes a lot of sense for smaller circuits, too.
I spent some significant dollars on an LPKP circuit board router
(mechanical etching thing) so that I could go from computer to
finished board at a high level of 'convenience.'  I'm still not
sure it was a good idea.  I think in the several years I've owned
the machine, I could have had every board I've made as a hobbyist
on it (which is not as many as I'd like, but still) made
professionally and still had money left over...

Arguably, back when WW was common, designing PCBs took more skill
than WW (hey, places hired high schools students like me to do WW
on prototypes, but the PCB layout guy was a skilled ancient :-)
But now there are cheap (or free) high quality packets like CadSoft
Eagle, and I don't think that it's a lot harder to come up to speed
with Eagle than it is to come up to speed from nothing with WW,
especially if you're talking about a 20MHz design and needing
twisted pair.  I WW'ed my senior design project, but that was
three or four chips on the periphery of an 5Mhz (?) system.
I WW'ed a keyboard encoder (ala TV Typewriter cookbook) that
was perhaps a dozen SSI chips.  And the aforementioned summer
job in HS.  None involved twisted pairs.  I'd be real nervous
using WW with signals that ran faster than about 2MHz.

The rats-nest vs neatly-routed wire argument is somewhat controversial.
The job said "be neat" (but things were slower then.)  The "serious"
designs allegedly tell you what length of wire to use for each
connection, cause the wire's delay is part of the system design.
(Cray-1 backplane, for example.)  debugging is simplified with a
neater layout, I think.

You can combine techniques.  Lay out the high frequency parts, power,
and decoupling and parts of the design that are "certain" on a PCB,
then use WW sockets for an wrap the rest.  This gives you the sort
of 'evaluation board' that many vendors now offer.  And in fact I've
seen an increasing number of projects in the 'senior design project'
class built on top of such evaluation boards (which is yet another
possibility.)

BillW

2005\03\07@064746 by Alan B. Pearce

face picon face
>So what do you "ole guys" use for prototyping? Just solder everything?

With modern PCB CAD packages such as Eagle, it is just as quick, or probably
quicker, to lay out a PCB and send it off to get a prototype one made. Less
errors, and if you do need to change the wiring, then it is easier to cut
the track and run a jumper wire. Jumper wires on PCB's is the best use for
wire wrap wire these days.

Just wait until you need to dig into the rats nest of wires to find the one
that you wired wrong. On a PCB CAD package if the wire is wrong, then it is
shown wrong on the schematic.

2005\03\07@064954 by Alan B. Pearce

face picon face
>In the late 70's the CBC television broadcast delay
>center was run entirely on racks worth of wire wrapped
>combinatorial logic so it CAN be made reliably.
>
>And don't forget the very speedy PDP 8 series of computers
>the were entirely wire wrapped backplanes and controllers.
>Async clocks at more than 2 MHz.

Do not forget that were not hand wire wrapped, but done by machines working
from CAD packages that verified the connections the same way that PCB CAD
packages do. That is a very different scenario to the hand wrap that is
being proposed.

2005\03\07@065101 by ThePicMan

flavicon
face
At 15.14 2005.03.06 -0700, you wrote:
{Quote hidden}

Usually I make prototypes using microboards (you know, those vetronite
prototyping boards full of holes, every 2.54mm).. I don't know the exact
english name.
I place the components and then use 30 AWG (or bigger, for power/ground)
wirewrap kynar wires, BUT solder it to the components and microboard.

Do all the scary things (expecially MHz wise) that I've been reading in
this thread about wirewrapping apply also to my (very common AFAIK) way
to make prototypes?

I like to prototype this way, and only then start working on the PCB..

I've been making PIC boards (using 40MHz oscillator ICs) this way and
never encountered any problem. Have I been lucky, so to speak?

Greets,
TPM

2005\03\07@074308 by Jake Anderson

flavicon
face
eagle takes about a day to "not suck" at it
you probably wont do everything right but eh close enough

one off projects I make I wire up on "strip board"? and solder.
thing to watch on that is to make sure you have all the tracks cut you are
meant to
I place all the chips solder them in then mark the track cuts with a marker
(remember you must cut the tracks down the centre of the IC, *that's* why
its getting warm ;->, and that 20V bridge way off to the other side with the
tracks running to your MSSP serial input pin wont help either)
then wire it up and cut the tracks (adding cut track marks as I wire)
projects wired up that way have flown in many of my hobby scale rockets (up
to H class) and in 100G acceleration sounding rockets.



> {Original Message removed}

2005\03\07@081639 by olin_piclist

face picon face
Jake Brownson wrote:
> So what do you "ole guys" use for prototyping? Just solder everything?

Of course, how else do you expect to connect the various eyelets on the
bottom of the tube sockets together?  The easiest way is to use the
components, like resistors and capacitors, to make the connections.  This is
where 1/2W resistors really help, instead of those newfangled 1/4W jobbies.
Just make sure that any high impedence lines, like the grid connections, are
run close to the chassis so they don't pick up as much noise.  Also keep the
front end circuit with a 12AUX7A or similar as far from the power back end
as possible to avoid unwanted pickup feedback.  For the same reason, you
probably want to give the front end it's own filtered 200V supply, and maybe
filtered DC for the filliments.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\03\07@082255 by olin_piclist

face picon face
> There's no hot iron to worry about burning yourself or
> others with,

That's really no problem once you learn to hold the fat end, not the pointy
end.  If it still bothers you, then you should consider a different career.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\03\07@090435 by alan smith

picon face
> > So what do you "ole guys" use for prototyping?
> Just solder everything?

Actually...yes.

Simple circuit....do a PCB.  Pretty cheap if you do a
double sided no silk screen or solder mask.  Time you
use to do the wire wrap can be made up with doing a
board.

Back in the day....i hated wirewrap.  So I did solder
everything.  I used belwire, just burned off the
insulation, tinned the wire and soldered.  Fast and
more reliable.




       
               
__________________________________
Celebrate Yahoo!'s 10th Birthday!
Yahoo! Netrospective: 100 Moments of the Web
http://birthday.yahoo.com/netrospective/

2005\03\07@091802 by Russell McMahon

face
flavicon
face
> Of course, how else do you expect to connect the various eyelets on
> the
> bottom of the tube sockets together?  The easiest way is to use the
> components, like resistors and capacitors, to make the connections.

> Also keep the
> front end circuit with a 12AUX7A or similar as far from the power
> back end
> as possible to avoid unwanted pickup feedback.  For the same reason,
> you
> probably want to give the front end it's own filtered 200V supply,
> and maybe
> filtered DC for the filliments.

A word of caution here. When running any sort of power - say dual
807's on up, you have to watch rigidity on long HT runs as the
conductors tend to "suck together" - if your modulation strikes a
mechanical resonance you can get some nasty arcing. If you're worried
about this you can run the finals at reduced voltage while
prototyping - say not over 500 or 600 volts.

Also, it pays to use something like an AVO for measuring screen grid
and plate circuits. Those wimpy modern yellow plastic meters have a
tendemcy to emulate an arc welder internallyu when you put 1000 volts
on them on the 1000 volt range.

Wire wrapping isn't really necessary in a formal sense. You just poke
the wire end through the hole in the tag strip and twist it around a
few times. Soldering is nice but optional. Do trim the ends of the
wire if you want to avoid corona discharge though. Whatever you do
don't let the wire ends drop down into the tube bases between the
pins. Can be very exciting.

If the 200 volts Olin mentions is a bit much for interfacing with the
solid state sections you can always try 6CW4's. These are quite happy
on 30 volts. This is a bit marginal for OC71s though so you may have
to compromise.

Hope that helps.



       RM






:-)

2005\03\07@092136 by John Ferrell

face picon face
"12AUX7"? I think you mean 12AX7...
Also, a good 250 watt soldering gun is helpful...

John Ferrell
http://DixieNC.US

{Original Message removed}

2005\03\07@092558 by Paul James E.

picon face

Negative on the DC for the filaments.   Modern (60's to now) tubes have
heaters that are designed for AC.   If you use DC, there is a chance of
premature failure of the heater because of migration.  The heater is
designed to run off AC. The cathode then is the common return point.
This way, you don't get the AC hum. The 12AU7 may have a center tapped
heater.  If this is the case, you can connect 12.6 VAC to the ends of the
heater and the CT will be left unconnected.  The current in this
configuration should be about 150ma.   Or you can connect the ends
together and place 6.3 VAC from the ends to the CT.  In this
configuration, you will draw around 300 ma.   I'm quoting this from memory,
so I could be wrong about the CT heater.  I know the 12AX7 has a CT heater.
And this tube is similar in construction and function.

Anyway, use AC for the heater.

                                                  Regards,

                                                    Jim




{Quote hidden}

> --

2005\03\07@093157 by Howard Winter

face
flavicon
picon face
Olin,

On Mon, 7 Mar 2005 08:16:51 -0500, Olin Lathrop wrote:

> Jake Brownson wrote:
> > So what do you "ole guys" use for prototyping? Just solder everything?
>
> Of course, how else do you expect to connect the various eyelets on the
> bottom of the tube sockets together?  

ROFL!

>...<
> For the same reason, you
> probably want to give the front end it's own filtered 200V supply, and maybe
> filtered DC for the filliments.

Huh!  What's wrong with AC straight from the 6.3V transformer winding, as God and Marconi intended?   :-)

Cheers,

Howard Winter
(my grandfather owned a "Wireless Shop" in London before WWII, but sadly he died before I was old enough to
chat to him).


2005\03\07@093252 by Rob Young

picon face

>> There's no hot iron to worry about burning yourself or
>> others with,
>
> That's really no problem once you learn to hold the fat end, not the
> pointy
> end.  If it still bothers you, then you should consider a different
> career.
>
But what about when it is time to break into the big musical number and you
are swinging the iron around singing "Puttin' on the Ritz"!

Rob

2005\03\07@094716 by Michael Rigby-Jones

picon face


>-----Original Message-----
>From: @spam@piclist-bouncesKILLspamspammit.edu [KILLspampiclist-bouncesKILLspamspammit.edu]
>Sent: 07 March 2005 13:23
>To: Microcontroller discussion list - Public.
>Subject: Re: [EE] Wire wrapping insight needed!
>
>
>> There's no hot iron to worry about burning yourself or
>> others with,
>
>That's really no problem once you learn to hold the fat end,
>not the pointy end.  If it still bothers you, then you should
>consider a different career.

And don't forget, if you drop the iron DO NOT TRY TO CATCH IT!

Mike

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2005\03\07@095243 by Paul James E.

picon face

Update...I said earlier the the current draw would be 150ma and 300ma
respectively.  After I sent it, I realized iot should have been 300ma
and 600ma respectively.   I don't have a tube manual handy at this moment,
but I believe this to be correct.

                                                Regards,

                                                  Jim



{Quote hidden}

> --

2005\03\07@100140 by Dan Crews

picon face
Just to add my voice to the Cacophony,

I've switched to making my own PCB's for prototyping and haven't looked back.  

I use the pulsar toner-transfer system that needs tape,  access to a
laser printer(or photocopier), and a clothes iron(you have bought one
by now, haven't you?).  a PCB can be printed and masked in 5 min. and
etched in about 10.

http://www.pulsar.gs/index.html

setup cost:

Toner-transfer paper:  $15 from digikey, mouser or . . . (+ ~$5 for shipping)
plated board:       $5.00 from radio-shack
Ferric chloride:        $5.00 from radio-shack
etching tray, sponges, gloves, steel wool, tape, skittles, and other
needed lab gear: $5-10

so for about $30-40 you can get up to speed and make your own pcb's
with a time cost of the artwork time +15 min.  At that point, if a
minor mistake is made, you kick yourself for five minutes, rework the
artwork for five, and recreate in 15, and you're back up and running
in under a 1/2 hr.

Dan Crews, E.I.T.
(RemoveMEcrews.danTakeThisOuTspamgmail.com)  <><

2005\03\07@100703 by Howard Winter

face
flavicon
picon face
Mike,

On Mon, 7 Mar 2005 14:46:49 -0000, Michael Rigby-Jones wrote:
>...<
> And don't forget, if you drop the iron DO NOT TRY TO CATCH IT!

Being a habitually clumsy person (when I was a kid my father wondered whether I was brain-damaged, because my
hand-eye coordination was so poor - the jury is still out! :-) I have had a *lot* of practice at catching
things.  I have found that I can decide on a course of action in the time between dropping/knocking something
and it hitting the floor.  Courses of action range from getting out of the way (dropped knives, cups
containing coffee, heavy objects), trying to catch it (empty cups, buttered toast, non-sharp objects) catching
the cable (soldering irons, wall-wart PSUs) or trying to break the fall with my foot (breakables where I'm too
late to catch them - usually cups / glasses).  My best result was getting my foot under a falling raw egg high
enough that it slowed it down, then lowering my foot with it on top so it survived!  I can't seem to stop
being clumsy, but I have developed a very good recovery technique!  :-)

Of course, the First Thing you learn as an electronics hobbyist is which end of a soldering-iron gets hot...
and I have the scars to prove it!  :-#

Cheers,


Howard Winter
St.Albans, England


2005\03\07@101711 by Wouter van Ooijen
face picon face
> And don't forget, if you drop the iron DO NOT TRY TO CATCH IT!

You are all sissies. When I started soldering I did not have one of
those nice low-wattage irons. I used my mothers 150 Watt iron (she did
some metal works as hobby). Now that is an iron to fetch at the slender
side! (Which I often did, otherwise it would fall on the carpet and that
would mean big trouble! Now I my only problem was to hide the smell of
burned flesh...).

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu



2005\03\07@103647 by Midgley John

flavicon
face
I'm deeply ashamed to admit that I use stripboard - the kind of thing that AoE would call "strictly bush-league" (whatever that means).

Whereas I used to use an acre of stripboard and work it out as I went along, I now use a combination of TinyCAD for the schematic and then I import the netlist into VCAD which is a stripboard layout aid. There I a can mess about to my heart's content, shoehorning circuits into a tiny area - and they work 1st time too!

John

{Original Message removed}

2005\03\07@110729 by Alan B. Pearce

face picon face
>Of course, the First Thing you learn as an electronics
>hobbyist is which end of a soldering-iron gets hot...
>and I have the scars to prove it!  :-#

It's not nick-named "the hotrod" for nothing ... :)))

Alan (lacking V8 power)

2005\03\07@110939 by Alan B. Pearce

face picon face
>"12AUX7"? I think you mean 12AX7...

's all right, he knows the 12AU7 and 12AX7 come in the same package, and are
pin compatible, he's just forgot about the 12AT7 ... also pin compatible ...

Does our uni student have the feeling of an apprentice sent to the stores
for a "long weight" ???

2005\03\07@114233 by William Chops Westfield

face picon face
On Mar 7, 2005, at 3:37 AM, ThePicMan wrote:
>
> I've been making PIC boards (using 40MHz oscillator ICs) this way and
> never encountered any problem. Have I been lucky, so to speak?
>
>
Well, generally the only part of a 40MHz PIC design that actually
RUNS at 40MHz is the oscillator itself, and some of the internal
logic.  Right away stuff is divided down to only running at 10MHz,
and the fastest you can toggle a pin from SW is what, 5MHz? (and
that's rarely done.)  Your average microcontroller is like a
microprocessor evaluation/prototype board, all inside one chip.

This is relevant to the original question, too.  You have to
pay attention to HOW MUCH of your design is high frequency.  Having
a little section over here where you generate video doesn't mean
you have to use twisted pairs all over the board.  You need to be
aware of which parts of the circuit have HF issues, which parts have
high current issues, and which are the parts where you can relax.
(This carries over onto PCBs and other design techniques too, though
perhaps starting at higher frequencies.)

BillW

2005\03\07@120926 by William C. Wilson, Jr.

flavicon
face

>> > So what do you "ole guys" use for prototyping?
>> Just solder everything?

For me, it depends on what I'm prototyping.

If it is small, I'll breadboard it first to make sure it works.
Then I'll either wirewrap, solder, or do a PCB based on how quickly
I need to get it working, how long I need it work, and the environment
that it works in.

If it's something that I'm only going to use and maybe only use it
for an hour or two to test/play with it and it won't fit on a bread
board I'll wirewrap it. Then I can disassemble it when I'm done.

If it is an emergency repair, I'll wirewrap the parts, solder the
wraps if possible, and then order up a PCB. But I can wirewrap quicker
than I can solder. The other people I work with will just solder
and order a PCB.

If it is more than 100 connections, I use a PCB because it is easier
to debug.

Something to remember is that with experience, you won't be
prototyping the little stuff. When I first started I would
breadboard something as simple as an Hbridge to do motor control
just to make sure I was doing it correctly. These days I could
draw that circuit from memory and order a PCB.

Also with experience, most people develop a library of circuits
and parts that they know work and they just import them into
their prototype. I'm prototyping a specialized printer at the
moment with a PCB that would have scared me to death years ago,
but for the "prototype PCB" I imported the power supply layout,
the motor control layouts, the sensor layout, and most of the
microcontroller layout from circuits that I've done in the past.
So 90% of the PCB protyping plus parts list was done in about
30 minutes. Another 5% of the prototype PCB will be tweaking what I
imported (different resistor here, different capacitor there, etc).
After that is done, I'm going to order a PCB of what I have and
then breadboard the remaining 5% of the prototype, connect the
breadboard to the ordered PCB, make whatever changes need to be
made, then order up the finalized PCB.


--
Cris Wilson
Clemson University
Daniel 212
spamBeGonecrisspamBeGonespamclemson.edu

2005\03\07@130047 by olin_piclist

face picon face
John Ferrell wrote:
> "12AUX7"? I think you mean 12AX7...

I don't have my RCA manual in this office, so I'll have to check later.  I
do remember there were two version, one was a special lower noise version of
the other.  The low noise version was a popular front end for microphone
amplifiers.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\03\07@131118 by Martin McCormick

flavicon
face
Jake Brownson writes:
>Wow, I don't know why everybody is complaining about WWing. In my
>Junior level microprocessors I just completed, and in my PLDs class
>Sophomore year we did _plenty_ of wire wrapping.

       I'll put in my $0.02, here.  It may well be that a beautiful
fabricated multi-layer circuit board is the state of the art, but is
this really the best approach for a class unless that is the purpose
of the class?  Unless one is lucky and it works the first or second
time, the amount of time spent trouble-shooting it and the expense of
new material not to mention that most precious commodity which is time
will quickly slow down what might be an otherwise simple project.

       My Master's degree is in Occupational and Adult Education
which does not, of course, make me all-knowing about everything, but
we had more than one discussion in the course of study about what
makes for good technical education.  If you are trying to teach
specific concepts, anything that raises issues that are not related to
the concepts being tought are distractions.  Some are unavoidable, but
nonetheless, they provide noise which dilutes the signal.

       Wire wrapping isn't state of the art any more, but it doesn't
take a tremendous amount of skill to master.  Fabricating boards is
easier than it used to be, but it still requires skill and practice
along with some specialized materials and tools that may or may not be
available.

       I agree with the technical reasons given by several why WW
isn't good in a production environment, but it is still good enough
to provide a viable alternative for students or hobbiests.

       Follow the guidelines given by several others on the list for
keeping noise out of your circuit and the wire-wrap version will most
likely work just fine.

Martin McCormick WB5AGZ  Stillwater, OK
OSU Information Technology Division Network Operations Group

2005\03\07@133214 by Mike Hawkshaw

flavicon
face
From: "Paul James E."
Subject: Re: [EE] Wire wrapping insight needed!

>  Negative on the DC for the filaments.   Modern (60's to now) tubes have
>  heaters that are designed for AC.   If you use DC, there is a chance of
>  premature failure of the heater because of migration.
This is true for directly heated cathodes, but there are some tubes that
have an indirectly heated cathode and it is quite OK to use DC on those. For
example high power klystrons for UHF TV that we have in service use DC
fills. The warm up time is of the order of 5 minutes.

>  The heater is
>  designed to run off AC. The cathode then is the common return point.
>  This way, you don't get the AC hum. The 12AU7 may have a center tapped
>  heater.......
I've never heard of this, but for AC heaters in tubes where hum is a
problem, it is usual to connect the centre of a linear potentiometer to
ground, and then one of the fills connections to each of the ends. The pot
is then adjusted for least hum on the output. This circuit was called a hum
dinger, though the term has fallen into dis (re) use.

Cheers...Mike.


2005\03\07@133755 by olin_piclist

face picon face
Howard Winter wrote:
> Huh!  What's wrong with AC straight from the 6.3V transformer winding,
> as God and Marconi intended?   :-)

I'm not so sure about Marconi, but maybe DeForest.  Anyway, I agree that
it's fine to use AC when the heater is designed that way most of the time.
I do remember seeing a very sensitive circuit that had filtered DC even for
AC fillaments just to get a little less noise.  Maybe it was a bad, design,
I don't know.  At the time was a kid eagerly soaking up what the supposed
experts were doing.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\03\07@140934 by Peter L. Peres

picon face


On Sun, 6 Mar 2005, Jake Brownson wrote:

> * Keep high frequency/noisy lines far away from the sensitive ones, and short

I like to use twisted pair ww wire for that. About 1 turn/in, the shield
wire is grounded at the source and sometimes also at the target. I don't
know what impedance such a line has but it caused no trouble at up to
30MHz.

Peter

2005\03\07@141026 by Richard.Prosser

flavicon
face

I still am - although not a kid anymore - unfortunately.
(Which is why I continue with the list).

RP



At the time was a kid eagerly soaking up what the supposed
experts were doing.






2005\03\07@141128 by Bob Ammerman

picon face
There were 12AU7, 12AT7 and 12AX7 at a minimum. All were dual triodes. I
couldn't say what made them different one from the other.

[One of my earliest electronics projects was building a flip-flop using a
12A?7 tube.]

Bob Ammerman
RAm Systems.


{Original Message removed}

2005\03\07@161108 by Paul James E.

picon face

The bulk of the tubes I speak of here have indirectly heated cathodes.
Which was my point in my previous post.  With an indirectly heated cathode,
the heater (filament) is run off AC.  If run off DC, migration will weaken
one end (anode end I believe) of the heater.  And due to the fact that the
cathode is heated, thermal inertia of the cathode sleeve keeps the
temperature relatively steady.    And the cathode is the common point in
the circuit.

In filament tubes, the filament is designed to be operated off DC, such
as in battery tubes (ie..1S4, 1T4, 3V5, etc.), and it acts (is) the
cathode.  Or at least one side of it anyway.  Also, the old two digit
(actually three) tubes 01A, 03, 05, etc run off DC.  Because batteries
was the only practical source of current for them at the time.

But modern small receiving tubes, not counting transmitting tubes, or
magnetrons, cyclotrons, TWT's etc. that you'll run in today are designed
to be operated off AC.   Typically 6.3 or 12.6 VAC at 600ma and 300ma
respectively.

                                                  Regards,

                                                    Jim





{Quote hidden}

> --

2005\03\07@170711 by Russell McMahon

face
flavicon
face
> And don't forget, if you drop the iron DO NOT TRY TO CATCH IT!

Learning NOT to catch falling soldering irons is a painfully acquired
anti-reflex art (I found).


       RM


2005\03\07@172314 by Mike Hord

picon face
> > And don't forget, if you drop the iron DO NOT TRY TO CATCH IT!
>
> Learning NOT to catch falling soldering irons is a painfully acquired
> anti-reflex art (I found).

Indeed.  I learned the anti-reflex in the hardest possible manner...
Having no stand to prop up my iron and needing to reach
something, I popped the blunt end into my mouth and reached
across my work with my right hand (to the left).  Unable to find
the desired object by groping, I glanced to the left, poking the
tip of the iron into my left hand.

The anti-reflex lesson came a moment later when I tried to
catch the iron, which was falling because I (quite naturally)
opened my mouth to express my dismay at having stabbed
my tender paw with a sharp object covered in melted lead.

Two lessons for the price of one!

Mike H.

2005\03\07@181454 by Ben Hencke

picon face
I did the same thing for a while, skipping any kind of fancy transfer
paper. I just photocopied it onto plastic transparencies, then ironed
them onto the boards. Sure, I had to go back with an etching pen and
fix 20% of the traces, but its all good fun at the end of the day. For
50 cents an 8x10 you can't beat the price! The only time I had trouble
was when someone left the photocopier set to 95% reduction and I
couldn't figure out why all the parts wouldn't fit in the holes.

My $1/50
- Ben


On Mon, 7 Mar 2005 10:01:39 -0500, Dan Crews <TakeThisOuTcrews.danEraseMEspamspam_OUTgmail.com> wrote:
{Quote hidden}

> -

2005\03\07@185025 by olin_piclist

face picon face
Paul James E. wrote:
> The bulk of the tubes I speak of here have indirectly heated cathodes.
> Which was my point in my previous post.  With an indirectly heated
> cathode, the heater (filament) is run off AC.  If run off DC, migration
> will weaken one end (anode end I believe) of the heater.  And due to
> the fact that the cathode is heated, thermal inertia of the cathode
> sleeve keeps the temperature relatively steady.    And the cathode is
> the common point in the circuit.

This is all true, but there are still legitimate cases where you run an AC
heater on DC.  AC heater really means it is completely insulated from the
cathode.  However, there is still some capacitance.  Depending on the
cathode impedence, this can end up in the signal as hum.  Yes, in theory
both sides ballance out if you use the center tap, but in practise it's
never perfect.  Any voltage noise on the cathode only is directly on the
grid-cathode voltage, which is the signal that gets amplified by the tube.
The usual method of dealing with this is to ground the cathode in very
sensitive front end circuits, but a DC heater voltage is just another tool
in the bag of tricks.

By the way I scanned the 12AU7-A data sheet and put it at
http://www.embedinc.com/temp/12au7a.tif.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\03\07@225732 by Tony Smith

picon face
> -----Original Message-----
> From: piclist-bouncesEraseMEspam.....mit.edu [EraseMEpiclist-bouncesspammit.edu]On Behalf
> Of Michael Rigby-Jones
> Sent: Tuesday, 8 March 2005 1:47 AM
> To: Microcontroller discussion list - Public.
> Subject: RE: [EE] Wire wrapping insight needed!
>
> >That's really no problem once you learn to hold the fat end,
> >not the pointy end.  If it still bothers you, then you should
> >consider a different career.
>
> And don't forget, if you drop the iron DO NOT TRY TO CATCH IT!
>
> Mike


I was amazed at the size of the blister that resulted from picking up a 100
watt iron by the hot end.  Looked like a blown up glove.

Having learnt that lesson, I moved on to motorcycles & women.  More scars.

Tony

2005\03\07@225924 by William Chops Westfield

face picon face
On Mar 7, 2005, at 10:11 AM, Martin McCormick wrote:

> Wire wrapping isn't state of the art any more, but it doesn't
> take a tremendous amount of skill to master.

But successfully designing and building a HIGH FREQUENCY design
using WW *is* difficult, and the claim is that it is (now) at least
as difficult as having a PCB designed and made.  The "state of the
art" comment shouldn't have been made; it's irrelevant to the
discussion (as you point out, one doesn't need start-of-the-art
tools except for SOTA designs...)

There aren't really and "good" manufacturing methods for school
projects, IMO.  Protoboards will do for some projects, and WW
for others, but if this project actually has 16Mhz running around
enough for Twisted pair WW to be a realistic solution, it doesn't
fall into either of those categories, IMO.  With a production
quality PCB costing less than the average engineering textbook,
and not being significantly harder to learn than WW (a point
that can be argued), the PCB is not a solution that should be
eliminated without some careful thought.

No one has mentioned WW procedures.  It the absence of software
that actually generates a wire-list for you, you can wrap from
a schematic; highlight each wire as you wrap it, and every 10
wires or so you do continuity check of those wires and highlight
with a different color.  Some schematics are lousy for this, not
showing connections directly.  First level Debugging tends to
consist of going over the schematic looking for connections that
you missed and  don't even think you've wrapped...

BillW

2005\03\08@044010 by Alan B. Pearce

face picon face
>There were 12AU7, 12AT7 and 12AX7 at a minimum. All
>were dual triodes. I couldn't say what made them
>different one from the other.

I couldn't tell you which was which, but one was general purpose, one low
noise, and one ruggedised (think low microphonics for guitar amplifiers).

2005\03\08@074322 by olin_piclist

face picon face
William Chops Westfield wrote:
> The "state of the
> art" comment shouldn't have been made; it's irrelevant to the
> discussion (as you point out, one doesn't need start-of-the-art
> tools except for SOTA designs...)

Except when one is doing it to learn.  Learning a state of the art technique
as apposed to something hardly used anymore is valuable in itself.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\03\08@075426 by Bob Axtell

face picon face
Olin Lathrop wrote:

> William Chops Westfield wrote:
>
>> The "state of the
>> art" comment shouldn't have been made; it's irrelevant to the
>> discussion (as you point out, one doesn't need start-of-the-art
>> tools except for SOTA designs...)
>
>
> Except when one is doing it to learn.  Learning a state of the art
> technique
> as apposed to something hardly used anymore is valuable in itself.
>
>
> *****************************************************************
> Embed Inc, embedded system specialists in Littleton Massachusetts
> (978) 742-9014, http://www.embedinc.com

A perfect explanation, Olin. No clearer words are possible.

--
Note: To protect our network,
attachments must be sent to
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2005\03\08@094134 by John Ferrell

face picon face
Yes! The 12AT7 brings back fond memories of my first Ham TV transmitter...
The older I get, the harder it is to stay on topic!

John Ferrell
http://DixieNC.US

{Original Message removed}

2005\03\08@095427 by John Ferrell

face picon face
As I recall:
12AX7-- Twin triode audio tube very rugged construction to minimize
microphonics
12AT7-- Twin triode with reasonable power dissipation. Could be used as high
as about 600mhz in Ham applications
12AU7-- Pentode RF/IF/Mixer applications

No, I don't want to go back. THESE are the good old days.

John Ferrell
http://DixieNC.US

{Original Message removed}

2005\03\08@100223 by John Ferrell

face picon face
Ooops! That was a 12AU6... Once again the memory slips a digit.
John Ferrell
http://DixieNC.US

----- Original Message -----
From: "John Ferrell" <RemoveMEjohnferrellspam_OUTspamKILLspamearthlink.net>
To: "Microcontroller discussion list - Public." <RemoveMEpiclistTakeThisOuTspamspammit.edu>
Sent: Tuesday, March 08, 2005 9:57 AM
Subject: Re: [EE] Wire wrapping insight needed!


{Quote hidden}

>> --

2005\03\08@105805 by Dan Crews

picon face
I'll agree, transparencies can work, but I've had inconsistant
results.  I got a few projects running with it, but finally gave it up
for something more reliable. not the first tiem I've migrated!  I
started using plain copy paper -- then rice paper -- then wax paper --
then transparencies.

>From what I've learned, TT is all about technique, and some things
make technique easier than others.

The pulsar paper is only $1 a sheet, and in addition, I can easily use
a scrap taped to a sheet of copy paper (transparency scraps tend to
slip as they go through, smearing the artwork).  I can usually make
5-10 boards (all at diffrent times) from a single 8.5x11, while it's
1:1 with transparencies (unless I want to fill the sheet, but that
doesn't help itterations and future projects).

in the end there's a lot of give-and-take in TT technique, and I've
found the "special paper" tends to give more than it takes.


Dan Crews, E.I.T.
(crews.danSTOPspamspamspam_OUTgmail.com)  <><


On Mon, 7 Mar 2005 15:14:45 -0800, Ben Hencke <spamBeGonebrainstarSTOPspamspamEraseMEgmail.com> wrote:
> I did the same thing for a while, skipping any kind of fancy transfer
> paper. I just photocopied it onto plastic transparencies, then ironed
> them onto the boards. Sure, I had to go back with an etching pen and
> fix 20% of the traces, but its all good fun at the end of the day. For
> 50 cents an 8x10 you can't beat the price! The only time I had trouble
> was when someone left the photocopier set to 95% reduction and I
> couldn't figure out why all the parts wouldn't fit in the holes.
>
> My $1/50
> - Ben

2005\03\09@052656 by ThePicMan

flavicon
face
At 09.57 2005.03.08 -0500, you wrote:
>As I recall:
>12AX7-- Twin triode audio tube very rugged construction to minimize microphonics
>12AT7-- Twin triode with reasonable power dissipation. Could be used as high as about 600mhz in Ham applications
>12AU7-- Pentode RF/IF/Mixer applications
>
>No, I don't want to go back. THESE are the good old days.

Expecially for portability! *g* ;->



>John Ferrell
>http://DixieNC.US
>
>{Original Message removed}

2005\03\09@074923 by olin_piclist

face picon face
> 12AX7-- Twin triode audio tube very rugged construction to minimize
> microphonics
> 12AT7-- Twin triode with reasonable power dissipation.
> Could be used as high as about 600mhz in Ham applications
> 12AU7-- Pentode RF/IF/Mixer applications

Actually they were all twin triodes, the difference being noise level,
microphonics, power dissipation like you mentioned.  See
http://www.embedinc.com/temp/12au7a.tif.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\03\09@120103 by jrem

picon face
I have attained excellent results using magazine paper in a laser
printer.  Try some different magazines until you find the paper that's
right, the best stuff is clay soaked or something, the toner comes off
nice and doesn't smush out like it does when using Avery crack-and-peel
backing . . .

best of all is it's free.

Another good trick is using a spring-loaded center punch for the hole
location, then dremel for a drill, I can knock out a board in no time
flat.  But wire wrapping is still way cool in my book.

Regards, John.




--- Dan Crews <KILLspamcrews.danspamBeGonespamgmail.com> wrote:
{Quote hidden}

> --

2005\03\09@135014 by jrem

picon face
I believe the gain spec changed on each tube, there are AT, AY, AU, and
AX7's.



--- Bob Ammerman <@spam@rammerman@spam@spamspam_OUTverizon.net> wrote:
{Quote hidden}

> {Original Message removed}

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