Is anyone still using wire wrap for prototypes?

[trevorford]

Just did wire wrapping in an electronics program at my local college. I wasn't very interested at first because I figured it has died off due to the low cost of PCB manufacture but it has proven to be a fairly useful technique for prototyping.

[ataradov]

As recently as 2001 NASA allowed wire wraps on space flight hardware.

I know. Wire wrap is an excellent technique  for anything military or airspace related. It is one of the most reliable connections you can get. The thing is, it is way-way harder to do than any other technique, that's partly why it has died anywhere, but in places where reliability is the key.

[ataradov]

Wire wrap is a way to hold wires before adding solder.

Adding solder to the wire wrap kills any advantage of using it in a first place. Also, it is next to impossible on complex boards if you have 2-3 wires going to the same pin.

[SeanB]

Wire wrap is a way to hold wires before adding solder.

Adding solder to the wire wrap kills any advantage of using it in a first place. Also, it is next to impossible on complex boards if you have 2-3 wires going to the same pin.

Yes, hated that, made replacing a broken connector a real pain, in that you had to cut all the pins off the old one, then remove it, then put the new one in and redo all the wiring to the pins again. I cheated on the one socket, simply took a turned pin socket and put it in the old turned pin wire wrap socket with the worn out contacts, and soldered all those pins together. Then another in the top and the PROM back in there, with a locking wire around the lot ( avionics lives on locking wire, so it was common, but the cost of those pliers! I still want a pair, but they are $80 each) to make sure it never would come out.

I had pity on the engine guys, having to use 50m of locking wire, in a single loop around each ring section of the engine, to hold all those locking tabs and nuts in place. Locking wire was definitely a "Use ONCE" item.

[rstofer]

One key feature of a cut-strip-wrap gun (and tip) is the 'cut'.  The bit cuts the wire to length and this ensures a constant wrap length on the pin.  Not too many wraps, not too few.  Always the same.

Modified wrap is another feature.  A modified wrap will have one turn of insulation on the pin for mechanical strength before the bare wire wraps around for the electrical connection.  Not all manual tools will deliver a modified wrap.

http://www.nutsvolts.com/magazine/article/wire_wrap_is_alive_and_well

[CatalinaWOW]

When used in a disciplined way wire wrap is fine, but there are so many traps.

As stated before layout from the netlist is an important step.  Only three connections per pin.  Preferred layers.  Signal integrity can also be maintained, but now you are adding wire track and length to the list of things to remember.

Don't use the insulation displacement wire.  Sooner or later the insulation displaces somewhere where it shouldn't.  First as an intermittent (perhaps even a tunneling connection), but later it gets more permanent.  This can even happen with good insulation types if you accidently stretch a wire across the corner of one of those wire wrap pins.  They are sharp enough to cut Teflon over time.

Verification is a PITA, best done with an ohmmeter from pin to pin since a visual check is insanely difficult.  Of course you can make a visual check easier through use of multiple colors of wire, but that is yet another constraint during the planning step and another thing to keep track of when assembling.

If verification fails, or if you use fire it up and look for smoke and signals and find a problem, it is never fun to find and correct the problem.  Murphy says it will never be in the top connection.

It all depends on you, your style and capabilities, but my wire wrap stuff stays in a bin somewhere in one of the storage sheds, with proto boards for really simple prototypes and laying out a pwb for more complex stuff being the way I actually do things.

[obiwanjacobi]

I still have some left over 25 year old wire wrap sockets and headers. In the early 90's I worked at a place where we used that to prototype. Never used it since...

[Kjelt]

Wire wrap is a way to hold wires before adding solder.

Adding solder to the wire wrap kills any advantage of using it in a first place. Also, it is next to impossible on complex boards if you have 2-3 wires going to the same pin.

For any soldering joint the parts should be mechanically connected first, soldered second. Turning a wire around a pin a few times is an excellent mechanical connection before soldering it.
But if you wirewrap everything with the correct tools and sockets than I agree you should not solder it.

As recently as 2001 NASA allowed wire wraps on space flight hardware.

Does this choice have anything to do with the magical tinwhiskers where everyone is so panicking about? It is no fun to see a spacecraft fail at millions of miles distance 10 years after launch because of some tin whiskers.

[KL27x]

I wirewrap with solderless breadboard. Stick the IC's and whatnot's into the solderless breadboard. Instead of sticking in jumper wires to make connections, stick in long rows of pin header next to the components. Then wrap the connections pin to pin. This way the jumpers don't build a huge mess where everything moves/wiggles when you touch it.

There are two main varieties of 30AWG kynar wrapping wire. One is designed to be cut/stripped/wrapped by a wrap gun in one action (CSW). The insulation is more slick and brittle and can be easily stripped with a fingernail. But the insulation is a little less malleable so the wires don't stay where you put/bend them as well as the regular stuff.

I have never used a wrap gun. Little hand tools work fine, but FYI the recent production Radio Shack wrap tool is out of spec and is a pain to wrap with. The nub is too far from the center hole and allows the wire to double over itself. Very frustrating. I would avoid these and go with OK industries.  OTOH, the stripper in the Radio shack tool is very handy.

[Tomorokoshi]

I did a couple projects with wire wrap a long time ago. Started with those push-in breadboard things and transferred the completed designs to wire wrap.

Once I had a summer job at an electronics factory. In the back was a large machine, which somewhat resembled a milling machine, and it had a 48" x 48" X-Y table. The head did automatic point-to-point wire wrapping. I didn't see it in action, but I did see it with the large panels loaded on the table.

[bson]

where will you get those carrier things?

No problem.
http://www.ebay.com/itm/AUGAT-614-CG1-14-PIN-HIGH-REL-COMPONENT-CARRIERS-5-pcs-/170898461365?hash=item27ca5792b5:m:mbP2lrklrvm5Dyw11wu7NCA
Mouser and Digi-Key also have them, but they're really hard to find (they call them something different).
I use them for breadboarding sometimes.

[Kalvin]

Here's a nice, pretty dense FPGA-design made using Wire-Wrap technique:

https://youtu.be/C8txvmXUIJQ?t=531

[RoGeorge]

...one of my reverse print servers...

What is a "reverse print server"?

[joeqsmith]

...one of my reverse print servers...

What is a "reverse print server"?

You watched the video and did not understand?       

A fair amount of older test equipment uses the Centronics parallel printer port to attach them to a printer.  Scopes, logic analyzers, spectrum analyzers, network analyzers are all tools where you may want to capture a screen shot.   Printers have been using Ethernet for many years.  Early on, we would use a print server that allowed printing to a Centronics or serial based printer from Ethernet.   These devices are just the opposite.  The take data in from a Centronics port, simulating a printer and then send the data via Ethernet to a printer. 

The FPGA on this particular unit basically simulates the Centronics port.  It also performs the DRAM refresh and acts as a DMA controller.  The 6811 obviously can't directly access this much memory so the FPGA also acts as a bus expansion.  The reason for the DRAM is that the protocol embeds a value of how much data is being sent.  This device needs to queue up the entire data to determine this. 

Last picture is showing the final stages of developing the software and FPGA.  There is an Ethernet print sever being used to convert the Ethernet to a Centronics port that feds into the reverse print server.  The very old Pentica MIME is actually hacked to run at the faster clock speeds of the later microcontrollers. 


     

[RoGeorge]

Didn't watched the video, just googled the term and it was not clear, sorry. So, it's a Centronics to LAN "translator" for printers.

Thank you for the explanation.

[joeqsmith]

I doubt you will find a device like this still today.  Newer equipment will typically have better ways to get data out of them so I doubt there is a market for it.  Back when I designed it, we had the print servers so it only seemed logical to call it a reverse print server.   

[Kalvin]

Here's a nice, pretty dense FPGA-design made using Wire-Wrap technique:

https://youtu.be/C8txvmXUIJQ?t=531

What sort of nut job would attempt such a thing?  Oh wait. 

  Great, neat and professional job you have done! Thanks for sharing!

[@rt]

I tried wire wrap for a project using all NIS sockets from eBay,
and it didn't get past one project.
Still the stripping is the hassle, and once that is done, I can't imagine
wrapping being faster... though admittedly, I haven't seen a pro do it.

Stripping is also where the potential is to damage the wire.

[CatalinaWOW]

I tried wire wrap for a project using all NIS sockets from eBay,
and it didn't get past one project.
Still the stripping is the hassle, and once that is done, I can't imagine
wrapping being faster... though admittedly, I haven't seen a pro do it.

Stripping is also where the potential is to damage the wire.

I agree, wire wrap is not that good an option now.  Back in the day you could buy kits of prestripped wire in various lengths.  Totally skipped the step of stripping at the cost of some dollars and storage space.  I haven't looked for years, you might still be able to buy these.