Network

S

[email protected]

Jan 1, 1970
0
I want to do make some prototype microcontroller boards with an 8051,
memory, latches, ... I think there will be about 10 ICs. I am new to
wire wrapping and need to purchase the tools, wire, and prototyping
board.

Can someone give me advice on what tools, prototyping boards to use?

Also best practices advice would be nice. I realize the importance of
decoupling caps, but what about things like:

choosing boards with ground planes, power buses, and connecting power
and ground pins.

what wire gages to use. Same for power, ground, and signal?

Any tricks for connecting data and address buses?

Specific manufacturers and part #s for tools and boards would be great.

Scott

T

Tim Wescott

Jan 1, 1970
0
I want to do make some prototype microcontroller boards with an 8051,
memory, latches, ... I think there will be about 10 ICs. I am new to
wire wrapping and need to purchase the tools, wire, and prototyping
board.

Can someone give me advice on what tools, prototyping boards to use?

Also best practices advice would be nice. I realize the importance of
decoupling caps, but what about things like:

choosing boards with ground planes, power buses, and connecting power
and ground pins.

what wire gages to use. Same for power, ground, and signal?

Any tricks for connecting data and address buses?

Specific manufacturers and part #s for tools and boards would be great.
By the time you spend enough to be up and running efficiently doing wire
wrap you will have spent enough for your first two quick-turn 2-layer
prototype board designs -- and soldered boards are much better than
wire-wrap.

L

Luhan Monat

Jan 1, 1970
0
I want to do make some prototype microcontroller boards with an 8051,
memory, latches, ... I think there will be about 10 ICs. I am new to
wire wrapping and need to purchase the tools, wire, and prototyping
board.

Can someone give me advice on what tools, prototyping boards to use?

Also best practices advice would be nice. I realize the importance of
decoupling caps, but what about things like:

choosing boards with ground planes, power buses, and connecting power
and ground pins.

what wire gages to use. Same for power, ground, and signal?

Any tricks for connecting data and address buses?

Specific manufacturers and part #s for tools and boards would be great.

Scott

Wire wrapping is a good choice if you are not very experienced.
Microcontrollers, unlike microprocessors, are very forgiving on layout
and such since rom and ram are internal.

Wire up all the power and ground lines first. Run redundant connections
in a 'matrix' manner. Put some 0.1 or so ceramic capacitors in several
places spaced around the board and tie into the power and grounds.

I use #30 wire for everything. Pad-per-hole boards allow you to solder
two diagonally opposite pins on DIP sockets to hold them in place.
Quarter watt resistors can be trimmed, bent, and inserted into DIP
sockets. The same for small capacitors.

Most all of the projects shown on the site below are done in wirewrap.

C

[email protected]

Jan 1, 1970
0
I hate to disagree with you Tim but a small project like this is ideal
for wire wrap. The whole job would take only 2 hours or so to do once
the circuit has been designed. Reliability is also good, wrap joints
are good for at least 10 years allthough I have 20 yearold boards that
still work fine.

D

dave garnett

Jan 1, 1970
0
I want to do make some prototype microcontroller boards with an 8051,
memory, latches, ... I think there will be about 10 ICs. I am new to
wire wrapping and need to purchase the tools, wire, and prototyping
board.

Can someone give me advice on what tools, prototyping boards to use?

Also best practices advice would be nice. I realize the importance of
decoupling caps, but what about things like:

choosing boards with ground planes, power buses, and connecting power
and ground pins.

what wire gages to use. Same for power, ground, and signal?

Any tricks for connecting data and address buses?

Specific manufacturers and part #s for tools and boards would be great.

Scott

I'd advise using a protoboard with a collander ground, and soldering
ground pins directly to it. You will save yourself untold trouble !
Similarly you can solder your decoupling caps directly between ground
and the Vcc pin.

able to get little labels which pushed onto dips and gave you the pin
numbers - saves hours of counting.

Another useful tip is that there are two sorts of wire-wrap wire -
tefzel and kynar insulated. Kynar is tough, resists soldering irons and
so on - but a pig to strip. Tefzel is easy to strip and not very robust.

If you buy a 'cut strip and wrap' bit they only work with Tefzel.

Go for 'modified wrap' tools (adds a couple of turns of insulated wire
at the start of a wrap, gives greater strength to a joint).

Your bus wiring strategy needs to take account of the fact that you get
a limited number of joints on a single pin - three typically, unless you
go for short pins.

P

Paul Burke

Jan 1, 1970
0
As one who has done a lot of wirewrapping in my time, my advice would be
not to do it. Prototype PCBs are now much more cheaply and quickly
available than in the past, and you are unlikely to get bad wraps or
signal problems. Wirewrapping gear is expensive, the less expensive the
slower it is. Use a simple free PCB package, go to PCB Pool or PCB Train
(in the UK- local alternatives otherwise), and you are also free to use
SM components in the design without clumsy and terrifically expensive

I still use it occasionally if I need a one off very simple (slow,
coarse analog or single- chip microcontroller) test circuit in a blazing
hurry, but then I've got all the gear lying idle already.

Paul Burke

L

Luhan Monat

Jan 1, 1970
0
Luhan said:
Wire wrapping is a good choice if you are not very experienced.
Microcontrollers, unlike microprocessors, are very forgiving on layout
and such since rom and ram are internal.

Wire up all the power and ground lines first. Run redundant connections
in a 'matrix' manner. Put some 0.1 or so ceramic capacitors in several
places spaced around the board and tie into the power and grounds.

I use #30 wire for everything. Pad-per-hole boards allow you to solder
two diagonally opposite pins on DIP sockets to hold them in place.
Quarter watt resistors can be trimmed, bent, and inserted into DIP
sockets. The same for small capacitors.

Most all of the projects shown on the site below are done in wirewrap.

Since I've been doing it so long, I forgot to mention. Use precut and
stripped #30 Kynar wire in a variety of colors. I buy them with a
different color for each length. Using a standard 'modified wrap' tool,
you can actually get about 5 wires on a '3 level' wirewrap socket. If
you need more, cut off up to half of the 1 inch bare end, 5 turns of
wrap is plenty good most of the time - thats a total of 20 contacts.

The big advantage of wirewrap over circuit boards, is that is both good
as a prototype (allowing experimentation and changes), and works as
reliably as a soldered board (some claim more so), over long periods of
time. I have never seen one fail - even after 30 years.

Good luck,

G

Guy Macon

Jan 1, 1970
0
dave said:
I'd advise using a protoboard with a collander ground, and soldering
ground pins directly to it. You will save yourself untold trouble !
Similarly you can solder your decoupling caps directly between ground
and the Vcc pin.

Good asvice. Use a small clip-on heat sink to stop the solder from
wicking up the pin.
able to get little labels which pushed onto dips and gave you the pin
numbers - saves hours of counting.

Find them here:
http://www.action-electronics.com/pdww.htm#Id
http://www.wassco.com/socketwrapid.html
http://www.abra-electronics.com/catalog/sockets/8id.html

Another tip: if you are connecting many pins together and go 1 to 2,
2 to 3, 3 to 4, 4 to 5, 5 to 6, you end up ripping the whole thing
out when you discover that 2 is in the wrong place. If instead you
go 1 to 2, 3 to 4, 5 to 6 then 2 to 3, 4 to 5, you only have to redo
three wires to correct an error.

G

Guy Macon

Jan 1, 1970
0
Paul said:
As one who has done a lot of wirewrapping in my time, my advice would be
not to do it. Prototype PCBs are now much more cheaply and quickly
available than in the past, and you are unlikely to get bad wraps or
signal problems. Wirewrapping gear is expensive, the less expensive the
slower it is. Use a simple free PCB package, go to PCB Pool or PCB Train
(in the UK- local alternatives otherwise), and you are also free to use
SM components in the design without clumsy and terrifically expensive

In my opinion, this depends a lot on your experience. If your skills
are such that the circuit is right the first time, buy a PCB. If
your skills are such that you end up rewiring again and again as you
learn, use wire wrap.

K

Ken Smith

Jan 1, 1970
0
I want to do make some prototype microcontroller boards with an 8051,
memory, latches, ... I think there will be about 10 ICs. I am new to
wire wrapping and need to purchase the tools, wire, and prototyping
board.

For most things, the soldered prototyping PCB patterns are a better option
than wire wrapping. With the soldered stuff, the board ends up larger in
the horz dimemsions but thinner. All the connections are made on the
component side so there is no constant flipping of the PCB.

the pins came up on the component side. This made for very easy wire
wrapping.

I prefer a hand wrapping tool to an electric gun. In the hands of a
skilled person, the gun is very fast but it takes more care to use.

There are wire wrap pins you can force or solder into hole of the board.
These make very good tie points to help connecting things up. Power and
ground connections often need extra tie points.

Extra tie points can also be used to modularize the circuit. If the
system breaks naturally into sections, making the connection between
sections via a row of pins can help to keep the changes managable when a
fault is found.

Buy good quality sockets. Cheap sockets are a false economy.

You want to run your power and ground wires as a grid. Each chip should
have a bypass of a 0.01 or 0.1uF. Line driver chips should have two
bypasses, one pointing North and the other pointing South so that they
connect to two different ground runs.

Twisted pairs of wire wrap wire are a good way to carry a sensitive signal
from place to place. It can also be helpful if you have a bus such as a
data bus and command signal running near each other.

J

John Larkin

Jan 1, 1970
0
I want to do make some prototype microcontroller boards with an 8051,
memory, latches, ... I think there will be about 10 ICs. I am new to
wire wrapping and need to purchase the tools, wire, and prototyping
board.

Can someone give me advice on what tools, prototyping boards to use?

Also best practices advice would be nice. I realize the importance of
decoupling caps, but what about things like:

choosing boards with ground planes, power buses, and connecting power
and ground pins.

what wire gages to use. Same for power, ground, and signal?

Any tricks for connecting data and address buses?

Specific manufacturers and part #s for tools and boards would be great.

Scott

come out way ahead laying out a PC board and having four or so fabbed
by AP Circuits or somebody for less than $100 total. You said "some boards" not just one. There's nothing more tedious than wrapping the same thing multiple times. John L Luhan Monat Jan 1, 1970 0 John said: My advice: don't wire-wrap. If your time is worth anything, you'll come out way ahead laying out a PC board and having four or so fabbed by AP Circuits or somebody for less than$100 total.

You said "some boards" not just one. There's nothing more tedious than
wrapping the same thing multiple times.

John

Wire-wrap the first one. Make sure it works. Have boards made for the
rest (http://www.expresspcb.com}. Reworking PC boards is also tedeous.

J

John Larkin

Jan 1, 1970
0
Wire-wrap the first one. Make sure it works. Have boards made for the
rest (http://www.expresspcb.com}. Reworking PC boards is also tedeous.

Design it, think about it carefully, and fab boards. It's good
discipline for real life. We never breadboard entire circuits; we go
directly to multilayer PCBs, and most of them are sellable first pass.

self-reinforcing.

John

L

Luhan Monat

Jan 1, 1970
0
John said:
Design it, think about it carefully, and fab boards. It's good
discipline for real life. We never breadboard entire circuits; we go
directly to multilayer PCBs, and most of them are sellable first pass.

self-reinforcing.

John

Hey, I've done that for purely digital circuits. For analog and mixed
signal stuff, no way!

T

Terry Given

Jan 1, 1970
0
John said:
Design it, think about it carefully, and fab boards. It's good
discipline for real life. We never breadboard entire circuits; we go
directly to multilayer PCBs, and most of them are sellable first pass.

self-reinforcing.

John

hear hear!

Its amazing what a good production department can do with rework

a contract mfg we used in NH showed us a rework they did for one
customer, who forgot a wire under a 512-pin BGA. So these guys (alas,
cant remember name) whipped the BGA off, re-balled it, soldered a dangly
wire onto the BGA then replaced it on the PCB. 100% success rate, almost
1000 boards. wow.

an OEM ups I got lumbered with had 90 rework mods. It took longer to
rework the pcb than to assemble it in the first place. So we built
17,000 like that [long story why we didnt re-spin the pcb]

careful design + careful spice + careful layout = its close enough to
working that we can make it go.

Cheers
Terry

J

John Larkin

Jan 1, 1970
0
Hey, I've done that for purely digital circuits. For analog and mixed
signal stuff, no way!

Oh, come on, take a walk on the wild side.

John

L

Luhan Monat

Jan 1, 1970
0
John said:
Oh, come on, take a walk on the wild side.

John

Hey John, did you notice what the this thread is called???

Game, set, and match.

R

Rich Webb

Jan 1, 1970
0
I want to do make some prototype microcontroller boards with an 8051,
memory, latches, ... I think there will be about 10 ICs. I am new to
wire wrapping and need to purchase the tools, wire, and prototyping
board.

Can someone give me advice on what tools, prototyping boards to use?

Also best practices advice would be nice. I realize the importance of
decoupling caps, but what about things like:

choosing boards with ground planes, power buses, and connecting power
and ground pins.

what wire gages to use. Same for power, ground, and signal?

Any tricks for connecting data and address buses?

Specific manufacturers and part #s for tools and boards would be great.

Everyone has mentioned a modified wrap tool but nobody listed a specific
one. Get the OK Industries WSU-30M (these guys have it cheaper than
Digikey): http://www.web-tronics.com/wrto30awgmow.html for 30 gauge
reach for it occasionally.

You can use pre-stripped wire but it's easy enough to cut and strip from
a bulk spool. Use the tool above to do the stripping and use your finger
joint as a quick'n'dirty gauge for the length to strip. Goes fast.

G

Guy Macon

Jan 1, 1970
0
There are times when it is impossible to know what a circuit will do
without breadboarding and modification. For example, I once designed
a system that measured hydrocarbons in exhaust gasses by injecting them
into a Hydrogen-Oxygen flame that contained two gold plated electrodes,
applying 1,000 volts across the electrodes, and measured the resulting
microamp current. I didn't know how many stages of filtering I would
need to handle turbulance and still meet the response spec until I did
a handwired prototype and took some measurements.

R

Richard H.

Jan 1, 1970
0
Rich said:
Everyone has mentioned a modified wrap tool but nobody listed a specific
one. Get the OK Industries WSU-30M (these guys have it cheaper than
Digikey): http://www.web-tronics.com/wrto30awgmow.html for 30 gauge
reach for it occasionally.

Hmmm... double-ended?? That'd seem awkward to spin one-handed.

I got one of these when Radio Shack still had vacuum tube testers
in-store... it still works great.
The head spins freely, making it pretty low-fatigue to use one-handed;
stripper stores in the handle. It looks like they still stock it
in-store too.

Richard

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