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'[OT] Wire Wrapping'
1999\01\28@221137 by Sean Breheny

face picon face
Hi all,

I recently have seen quite a bit of talk about wire wrapping and I have a
very basic question about it: why do people like it as a prototyping
technique?

For my own prototyping, I use breadboards (the plug-in kind) for
non-sensitive stuff and then copper-plated standard grid boards, and
sometimes etch my own boards. It would seem to me, naively, that wire
wrapping is no better than breadboarding, since the lead lengths really
can't be kept much shorter (hence inductance is still a problem), and no
ground plane is available in either case (so "star" grounds are the only
way to avoid ground loops in either case). I must admit to never even
having tried it, but it must be at least a bit harder than just plugging
things into a breadboard. I also very rarely have intermittant contact
problems with breadboards (maybe I'm just lucky?)

I appreciate any answers people can give me because I would consider
switching my prototype technique if there is a significant advantage (one
of my favorite types of circuits to work on, in addition to PICs, are RF
circuits, and of course, I have trouble getting higher than a 10MHz BW with
circuits on plug-in breadboards because of, mainly, I would suspect
parasitic capacitance between rows of contacts. Perhaps this is less on
wire wrapped boards?)

Thanks,

Sean

+-------------------------------+
| Sean Breheny                  |
| Amateur Radio Callsign: KA3YXM|
| Electrical Engineering Student|
+-------------------------------+
Save lives, please look at http://www.all.org
Personal page: http://www.people.cornell.edu/pages/shb7
spam_OUTshb7TakeThisOuTspamcornell.edu  Phone(USA): (607) 253-0315 ICQ #: 3329174

1999\01\29@071816 by Bob Drzyzgula

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face
On Thu, Jan 28, 1999 at 10:09:59PM -0500, Sean Breheny wrote:
> Hi all,
>
> I recently have seen quite a bit of talk about wire wrapping and I have a
> very basic question about it: why do people like it as a prototyping
> technique?

Personally, I suck at ad-hoc soldering on grid boards :-)
I use the solderless breadboards as a sort of scratch pad
to try out ideas and check my thoughts, but they are kind
of problematic when one wants to test an entire circuit
in the intended environment.

> I appreciate any answers people can give me because I would consider
> switching my prototype technique if there is a significant advantage (one
> of my favorite types of circuits to work on, in addition to PICs, are RF
> circuits, and of course, I have trouble getting higher than a 10MHz BW with
> circuits on plug-in breadboards because of, mainly, I would suspect
> parasitic capacitance between rows of contacts. Perhaps this is less on
> wire wrapped boards?)

In the previous thread on wire wrapping, there was some
discussion about bandwidth limits of the technique. I
usually don't drive PICs above 4MHz, so it hasn't been
a problem. Also, the meLabs Pic Protoboards and the
Dontronics SIMM boards provide places to solder the
oscillator circuit into nice short PCB traces, which is
usually the fussiest part of what I do. In both  of those
designs there are nice transitions to a decent-sized grid
board for ad hoc work.

--Bob

--
============================================================
Bob Drzyzgula                             It's not a problem
.....bobKILLspamspam@spam@drzyzgula.org                until something bad happens
============================================================

1999\01\29@084732 by dave vanhorn

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face
At 07:07 AM 1/29/99 -0500, Bob Drzyzgula wrote:
>On Thu, Jan 28, 1999 at 10:09:59PM -0500, Sean Breheny wrote:
>> Hi all,
>>
>> I recently have seen quite a bit of talk about wire wrapping and I have a
>> very basic question about it: why do people like it as a prototyping
>> technique?
>
>Personally, I suck at ad-hoc soldering on grid boards :-)
>I use the solderless breadboards as a sort of scratch pad
>to try out ideas and check my thoughts, but they are kind
>of problematic when one wants to test an entire circuit
>in the intended environment.


Me, I use a copper clad board, plain. I "dead bug" the chips to it, taking
their ground pins directly to the copper.
The other pins are spread out, and connected with wire-wrap wire, soldered
on.  This has served well for high current switchers, a VHF 1W transmitter,
and a bunch of various others. (Currently an FM band synthesized transmitter)
I've standardized on an 8" x 12" board, which I made a slotted cabinet for,
with slots every 1/2". This allows me to swap projects on and off the bench
fairly fast.  If the project is Atmel 8515 based, I put down dual row
headers to connect to their development board, otherwise I put a tie in for
ICP or a socket for the CPU using a surfboard.

1999\01\29@093107 by Martin McCormick

flavicon
face
       The thing I like about perforated board and wire wrap
sockets is that if you like what you have made, you can just continue
to use it for decades and it will work.  When the need for the device
has passed, the components can largely be reused including the circuit
board.  I don't know of anything else that is as open-ended as this.

       Making PCB's is the only way to fly for mass-producing
circuits once they have been finalized, but the wire-wrap technology
is for a different purpose and serves that purpose very well.

Martin McCormick WB5AGZ  Stillwater, OK
OSU Center for Computing and Information Services Data Communications Group

1999\01\29@102403 by Reginald Neale

flavicon
face
Sean asked:
>
>I appreciate any answers people can give me because I would consider
>switching my prototype technique if there is a significant advantage (one
>of my favorite types of circuits to work on, in addition to PICs, are RF
>circuits, and of course, I have trouble getting higher than a 10MHz BW with
>circuits on plug-in breadboards because of, mainly, I would suspect
>parasitic capacitance between rows of contacts. Perhaps this is less on
>wire wrapped boards?)
>
 Sean:

 My opinion - wire-wrapped boards probably aren't going to be a whole
 lot better for RF circuits. For general prototyping, wire-wrapping
 is still a viable choice but it's not the solution to every problem.

 I don't use wire-wrap as much as I used to, but that's mostly because
 there is not as much occasion for building boards that are IC
 connection-intensive as opposed to component-intensive. It used to make
 sense to wire-wrap big blocks of discrete logic, but they have largely
 been replaced by PICs and other embedded micros where many of those
 functions are implemented in software.

 In theory, it's easy to make changes on a wire-wrap board. In practice,
 every time I have to make a change, it involves a lot of bottom wraps
 on multi-level wrapped pins. :-(

 Not sure whether this has already been mentioned, but wire-wrapped
 boards are not good in situations where the board is likely to get any
 rough handling. The pins are long and skinny, so they are easily bent
 and short together. The wire itself is tiny.  Because it's solid
 vs. stranded, it breaks easily if flexed.

 My personal evaluation of the effort involved in making or changing
 soldered connections vs. wire-wrapped ones is that it's close to a
 wash. If you're getting good results with your present prototyping
 technique, I'd stick with it.

 Just my .02 - hope this is helpful,

 Reg Neale

1999\01\30@050849 by paulb

flavicon
face
Sean Breheny wrote:

> and no ground plane is available in either case (so "star" grounds are
> the only way to avoid ground loops in either case).

 You've got me puzzled there.  What are these "ground loops" you are
trying to avoid?
--
 Cheers,
       Paul B.

1999\01\30@140726 by Byron A Jeff

face picon face
>
> Hi all,
>
> I recently have seen quite a bit of talk about wire wrapping and I have a
> very basic question about it: why do people like it as a prototyping
> technique?
>
> For my own prototyping, I use breadboards (the plug-in kind) for
> non-sensitive stuff

Breadboards are out for one simple reason: complete lack of stability. It's
simply too easy to pull a wire out of place.

I did breadboarding in college, including a 6802 based microcomputer. The
wiring problems turned me off to them forever.

> and then copper-plated standard grid boards, and
> sometimes etch my own boards.

I think I told my soldering story a couple of weeks ago. I got a RatShack
(probably my first mistake) grid board to put a Xmas light controller on.
I had quite a time with solder bridges even using the fine tipped soldering
iron and the .022 diameter solder. Next time I'll wire wrap it.

> It would seem to me, naively, that wire
> wrapping is no better than breadboarding, since the lead lengths really
> can't be kept much shorter (hence inductance is still a problem), and no
> ground plane is available in either case (so "star" grounds are the only
> way to avoid ground loops in either case).

Correct on the inductance, and also on the ground plane. If it's a big project
I'll create a power bus by soldering all the pins of a dual wire wrap header
together, then pull power and ground from the wire wrap pins underneath.

> I must admit to never even
> having tried it, but it must be at least a bit harder than just plugging
> things into a breadboard. I also very rarely have intermittant contact
> problems with breadboards (maybe I'm just lucky?)

The contacts didn't bother me as much as wires coming aloose. with wire wrap,
once a pin is wrapped, you literally have to destroy the wire to get it
detached from the pin. The secure mechanical connection is better than
breadboards and frankly better than solder. Again my perspective is from an
admittedly bad solderer. But I've had enough cold solder connections to
not wish for anymore.

>
> I appreciate any answers people can give me because I would consider
> switching my prototype technique if there is a significant advantage (one
> of my favorite types of circuits to work on, in addition to PICs, are RF
> circuits, and of course, I have trouble getting higher than a 10MHz BW with
> circuits on plug-in breadboards because of, mainly, I would suspect
> parasitic capacitance between rows of contacts. Perhaps this is less on
> wire wrapped boards?)

If done carefully. But I think that for the RF work, PCB boards are best.
But I don't do RF work. All of my electronics are microcontroller based. And
I can't remember the last time that I hand wrapped a uC board that didn't
work. I've had less than stellar results with automatic tools such as
Slit-N-Wrap and wire guns.

For me wire wrap represents the flexibility of breadboards coupled with the
mechanical stability of solder. I can experiment and modify a board and use
exactly the same board as a permanent fixture once it's done. The only thing
I wish I could get is the same board depth as solder.

So that's my thoughts on it.

BAJ

1999\01\30@142011 by dave vanhorn

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face
At 06:23 PM 1/30/99 +1000, Paul B. Webster VK2BZC wrote:
>Sean Breheny wrote:
>
>> and no ground plane is available in either case (so "star" grounds are
>> the only way to avoid ground loops in either case).
>
>  You've got me puzzled there.  What are these "ground loops" you are
>trying to avoid?


If a circuit grounds at two different points, then it is suceptible to
current flowing in the ground.
(Ground IS a signal!)  For example, I have a project where I am running a
stepper motor at 1A, next to a head amplifier with a gain figure of 7000.
If I let the head amp have more than one ground point, it could pick up
some voltage from the stepper's ground return current. The current in
ground becomes a voltage, if ground's resistance is not zero. (It never is).
If you tap ground at two points, there will be a voltage differential when
current is flowing. That voltage differential is then applied to your
circuit as if you inserted a voltage source in series with your grounds.

Since the head amp has only one ground point, it dosen't matter how much
current is flowing in ground, I don't see two points, therefore I don't
develop any voltage drop.  How you do this, is to take a functional block
of circuitry, and connect the grounds within it with large low Z traces,
then take one point, and connect it out to system ground with a single
trace, hopefully to a point where no current is flowing. In my case, I used
the neg lead of my main power supply cap as the "star point".  Each section
powered from that voltage has a single return trace to that point, or
whichever power supply cap they draw from. The power supply caps are
similarly linked.

It's just like your mom told you, only with current.. Put things back where
you got them from ! :)

1999\01\30@154715 by Larry Dewey

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face
At 02:06 PM 1/30/99 -0500, you wrote:
>>
>> Hi all,
>>
>> I recently have seen quite a bit of talk about wire wrapping and I have a
>> very basic question about it: why do people like it as a prototyping
>> technique?
>>
>> For my own prototyping, I use breadboards (the plug-in kind) for
>> non-sensitive stuff
>
>Breadboards are out for one simple reason: complete lack of stability. It's
>simply too easy to pull a wire out of place.
>
>I did breadboarding in college, including a 6802 based microcomputer. The
>wiring problems turned me off to them forever.
>

I've been using a breadboard for prototyping circuits for about five years,
and I'm very happy with the results.  Circuits are so easy to rewire when
the inevitable mistakes are discovered.  Usually my initial circuit looks
like a rat's nest of wires, but as it matures, I replace the ones that are
longer than necessary with wires that lay flat on the board.  This makes
the circuit more accessible and more mehanically stable.  It looks better too.

The only draw-back to the system that I have now is making mechanically
sound connections to outside devices such as an lcd module, power supply,
and db9 connectors.  As my board sprouts more of these, I'm going to have
to address this problem before long.

Larry
KG7LO
44 years old
PICing in Port Townsend, Washington

1999\01\31@193126 by Sean Breheny

face picon face
Hi all,

At 02:08 PM 1/30/99 -0500, you wrote:
>At 06:23 PM 1/30/99 +1000, Paul B. Webster VK2BZC wrote:
>>Sean Breheny wrote:
>>
>>> and no ground plane is available in either case (so "star" grounds are
>>> the only way to avoid ground loops in either case).
>>
>>  You've got me puzzled there.  What are these "ground loops" you are
>>trying to avoid?
>
>
>If a circuit grounds at two different points, then it is suceptible to
>current flowing in the ground.
>(Ground IS a signal!)  For example, I have a project where I am running a
>stepper motor at 1A, next to a head amplifier with a gain figure of 7000.

Yes, this is what I meant by ground loops. I am in the midst of a project
right now where this sort of thing affected me greatly. It was a real
learning experience! I just completed a design for an adjustable 3Amp power
supply. I wanted to keep output ripple below 5mV. If I used different
ground points for my voltage reference and my main output ground, and there
was a significant current flowing between them, I saw not only about a
100mV drop in the output voltage, but more importantly, a 50mV ripple.
Making these grounds the same point decreased it to 5mV. I even find this
true with little 78xx regulators. They are really decent regulators if you
make sure that you connect the return line from the stuff "downstream"
directly to the 78xx's GND pin. If you connect it further back, like back
at the rectifier, there will be a voltage error and a ripple voltage
proportional to the current and the resistance of the intervening wire. I
saw this first hand on my scope.

Regarding breadboards: I understand what Byron is saying about mechanical
stability, but usually this isn't a real problem for me. Just as Larry
pointed out, if one resists the temptation to use arbitrary length wires
and actually uses ones of appropriate length, this usually isn't a problem.
Just like Larry, the only time I really have a problem is when I try to
attach external components. It would be nice to find breadboards with mass
termination connectors built in. Anyone seen these?

Thanks to everyone for the comments. I think I will stay with breadboards
for now, but consider wire wrap for anthing that requires especially strong
mechanical connections in the prototype stage.

Sean

+---------------*----------------+
| Sean Breheny                   |
| Amateur Radio Callsign: KA3YXM |
| Electrical Engineering Student |
+---------------*----------------+
Save lives, please look at http://www.all.org
Personal page: http://www.people.cornell.edu/pages/shb7
shb7spamKILLspamcornell.edu  Phone(USA): (607) 253-0315 ICQ #: 3329174

1999\01\31@202532 by Steve Pillwein

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face
Larry Dewey wrote:

> The only draw-back to the system that I have now is making mechanically
> sound connections to outside devices such as an lcd module, power supply,
> and db9 connectors.  As my board sprouts more of these, I'm going to have
> to address this problem before long.
>
> Larry
> KG7LO
> 44 years old
> PICing in Port Townsend, Washington

A similar problem was hampering my ability to try different experiments when
I got started learning with PICs.  I soldered a ribbon cable to my LCD, but
found it was too time-consuming having to insert those tiny wires into the
breadboard.
It also wasn't very portable.  Then I came up with this solution:

I took a strip of   0.10" spaced single header and soldered the ribon cable to t
he

header.  I split the ribbon cable into three sections: 8-pin header for the data
lines,
3-pin for the control lines, and 3-pin for the power connections.  I used hot-me
lt

glue over the solder joints to re-inforce the cable so it can be inserted and
removed
quickly.  This arrangement is now quite conveniently inserted and removed and
makes prototyping with a breadboard less labour-intensive.

After reading PIC' up the Pace and author David Benson's suggestion of makiing a
n
84
on a board for experimenting, I made a PC-board with a 16C84, a 4mhz oscillator,
a

reset button, and an in-circuit programming header that interfaces with my PIC-1
a
programmer.  All the port lines and power connections are brought out to a
90-degree
0.10" header which plugs easily into a breadboard and frees up a lot of breadboa
rd

real-estate for the rest of the circuit.  I call it the '84-Board.

I have a few small breadboards that I can now have different prototypes on, and
it's just a matter of reprogramming the PIC and plugging '84 board into the
circuit
on the breadboard I'm working on.  Debug-test cycle is also much faster.

Steve

1999\01\31@225358 by Steve Pillwein

flavicon
face
My apologies if this is a repeat
posting.....I've had problems sending
this
to the list:


Larry Dewey wrote:

> The only draw-back to the system that
I have now is making mechanically
> sound connections to outside devices
such as an lcd module, power supply,
> and db9 connectors.  As my board
sprouts more of these, I'm going to have

> to address this problem before long.
>
> Larry
> KG7LO
> 44 years old
> PICing in Port Townsend, Washington

A similar problem was hampering my
ability to try different experiments
when
I got started learning with PICs.  I
soldered a ribbon cable to my LCD, but
found it was too time-consuming having
to insert those tiny wires into the
breadboard. It also wasn't very
portable.  Then I came up with this
solution:

I took a strip of   0.10" spaced single
header and soldered the ribon cable to
the header.  I split the ribbon cable
into three sections: 8-pin header for
the
data lines, 3-pin for the control lines,
and 3-pin for the power connections.  I
used hot-melt glue over the solder
joints to re-inforce the cable so it can
be
inserted and removed quickly.  This
arrangement is now quite conveniently
inserted and removed and makes
prototyping with a breadboard less
labour-
intensive.

After reading PIC' up the Pace and
author David Benson's suggestion of
makiing an 84 on a board for
experimenting, I made a PC-board with a
16C84, a 4mhz oscillator, a reset
button, and an in-circuit programming
header
that interfaces with my PIC-1a
programmer.  All the port lines and
power con-
nections are brought out to a 90-degree
0.10" header which plugs easily into a
breadboard and frees up a lot of
breadboard real-estate for the rest of
the
circuit.  I call it the '84-Board.

I have a few small breadboards that I
can now have different prototypes on,
and it's just a matter of reprogramming
the PIC and plugging '84 board into the
circuit on the breadboard I'm working
on.  Debug-test cycle is also much
faster.

Steve


'[OT] Wire Wrapping'
1999\02\01@042354 by Mark Willis
flavicon
face
Sean Breheny wrote:
> Hi all,
>
> I recently have seen quite a bit of talk about wire wrapping and I have a
> very basic question about it: why do people like it as a prototyping
> technique?
> <snipped>

 For several reasons, I use wire-wrap:

 I have kitties here.  Breadboards + little clawed paws = loose wires
all over the floor.  (See also "rough handling" <G>)

 Wirewrap's cheaper, more permanent and can be left in place easier
(Price a piece of perfboard vs. a solderless breadboard.)

 It's not a problem for slower logic circuits etc. (In some ways, it's
a real advantage to prototype/test/debug a circuit on wire-wrap or
breadboard - if you get it working right there, then re-do the
production circuit in PC board, you're going to have already solved most
all problems that might occur - and most stuff I've been doing is Serial
or Parallel port connected projects so not RF speed.  I agree on RF not
being optimal for wire-wrap unless you REALLY plan it out in advance.  I
try to minimize wire runs as best I can, anyways.)

 It's a lot easier, for prototyping purposes, to cut pieces of
perfboard out of my way to make a weird connector, a tab of a
transformer, or whatever, fit - if you have a transformer or the like
loose off a breadboard, it can break free easily.  Moto-tool or nibbler
are wonderful tools, also an X-Acto knife or scalpel work well for
shaving holes larger.

 Mark, .....mwillisKILLspamspam.....nwlink.com, Kent, WA

1999\02\01@065922 by paulb

flavicon
face
Steve Pillwein wrote:

> I used hot-melt glue over the solder joints to re-inforce the cable so
> it can be inserted and removed quickly.

 *Not* a wise move.  I just did that in my little light sequencer and
now want to get the stuff off so I can do the job properly with epoxy
(as I did when I made my first computer project 20 years ago with the
SC/MP ... sob!).

 Why?  Because the hot-melt does not harden sufficiently to prevent the
wires moving at the solder junction and breaking, and will make it even
harder to repair when they do!  In particular, the pressure of insertion
pushes individual pins up and down within the header pin strip.

 The thermoplastic carrier of the pin strip is purely to hold the pins
until soldered into a PCB; it is not made to withstand mechanical
stress, especially after soldering.  It may look like a neat "plug", but
it isn't!  Encapsulated in solid *epoxy* however, it will suffice.

 Next faux pas - the header pins may fit in the nylon "breadboard", but
they won't fit in anything else, especially not a machined-pin IC socket
or a piece cut therefrom.  Bother!  My second-line protyping is, you
see, Veroboard (matches the breadboard in some ways) but I wanted a
socket to fit the header "plug".

> After reading PIC' up the Pace and author David Benson's suggestion of
> makiing an 84 on a board for experimenting, I made a PC-board with a
> 16C84, a 4mhz oscillator, a reset button, and an in-circuit
> programming header that interfaces with my PIC-1a programmer.  All the
> port lines and power connections are brought out to a 90-degree
> 0.10" header which plugs easily into a breadboard and frees up a lot
> of breadboard real-estate for the rest of the circuit.  I call it the
> '84-Board.

 Resembles a Simmstick!  http://www.dontronics.com/dt101.html
--
 Cheers,
       Paul B.

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