Wire wrapping for prototypes - Page 1
Forum section: electronics / beginners

author: Sigmoid
author_rank: Frequent Contributor
timestamp: July 28, 2013, 10:24:43 pm
content: Hey,I read some pretty cool stuff about wire wrapping as a prototyping technique. Solderless, quick, reworkable, only needs a contactless prototyping board, and has some awesome pedigree - like most supercomputers in the cold war era were made this way.Though it also seems like a bloody chore.So I wonder if anyone's ever tried / used it, and what the verdict is compared to using solder trails or cutters on prototype boards...

author: HardBoot
author_rank: Regular Contributor
timestamp: July 28, 2013, 10:29:41 pm
content: If you have perfboard and wire wrap sockets, and the tool... it's not cheap for good stuff but quite reusable and easy once you're used to it.Wire wrapping wire is essential for soldering work so you want that either way.Male dip through-hole headers are good wrap posts, I'll often connect things together by wrapping instead of making a custom cable or use up my female jumpers.

author: WarSim
author_rank: Frequent Contributor
timestamp: July 28, 2013, 10:30:03 pm
content: Wire wrap done correctly requires wire wrap posts which are getting quite rare these days. Yes wire wrap can be applied to any square post but with lower reliability.Unless you are good at the technique it is not faster than soldering with equivalent skill.Wire wrap is only found on prototype backplane wiring these days. If you are looking for this solution, go for it. If you are looking for a PCB alternative I advise don't bother.

author: Corporate666
author_rank: Unknown
timestamp: July 28, 2013, 10:30:32 pm
content: Wire wrapping goes way back. I remember when I was first getting into electronics around 1988-1990, it was very popular..I bought a wire wrapping kit at Radio Shack that saw some use.I think today, with people shifting away from through hole parts, easy-to-use SMT adapters from Adafruit and Sparkfun available - it just isn't used that much anymore. Breadboarding won out. For reworking, I find jumpers and splices work better. And often more durable.

author: WarSim
author_rank: Frequent Contributor
timestamp: July 28, 2013, 10:34:46 pm
content: Wire wrap is very durable if done correctly with the correct tools/skill/posts.Over 30 year wire wrap installs are still working without fault.I consider this durable.Conversely wire wrapping to through hole legs is not durable, lucky to get 3 years.

author: westfw
author_rank: Super Contributor
timestamp: July 28, 2013, 10:56:34 pm
content: QuoteHuh? Standard WW posts are 0.025 inch square posts, which are still pretty common. I didn't THINK that there's a difference between WW 25mil posts and other 25mil posts! (theory says that the corners of the post bite into the wire, forming a reliable (gas-tight!) connection. So I suppose that WW could require posts of increased "hardness.")I had a summer job after HS that consisted mostly of wirewrapping prototypes...Wirewrap is NOT "quick." If you can do 30 connections an hour, you're doing pretty good. (including measure, cut, strip, wrap one end, route, wrap the other end.)These days, WW is depressingly expensive, having become a "slightly supported niche" rather than one of the mainstream techniques. The hand WW tool that used to be $10 at radioshack is now $30, and a 40-pin WW socket will set you back more than most 40pin chips (about $6.) (actually, it was never cheap. Those lovely WW panels you see occasionally cost a small fortune; but back then chips were a lot more expensive, too.)

author: dfmischler
author_rank: Frequent Contributor
timestamp: July 28, 2013, 10:59:27 pm
content: I designed and wire wrapped a few boards in the early 80's. Just debug/development support stuff of which only a few were needed. Can you still get the sockets now? And using only through-hole parts would be really limiting now.In the same era the company I worked for had a (Gardner-Denver?) CNC wire-wrap machine. I was told that you gave it a board with the sockets in place and fed the computer the "program" (wiring list) and it wired the whole board. My query "Why?" was answered with a flat statement that this was the most reliable proven technology to date for the target environment, and specified by the customer. Access to the room, materials, product and "programs" was highly controlled during production of what I was told were boards for the US Navy. Someone said the word "Trident" but I don't know if that was true. These boards were apparently populated and tested in an area where I had no access at any time, as I had no need to know about any of that.

author: HardBoot
author_rank: Regular Contributor
timestamp: July 28, 2013, 11:04:16 pm
content: Quote from: westfw on July 28, 2013, 10:56:34 pmWW posts are hexagonal and regular posts are square... in the real world there's no difference.Speed wise you can go pretty quick; cut, strip, strip, stick, wrap, stick, wrap, soldering is faster but it's not a big difference if you already have to cut and strip.

author: westfw
author_rank: Super Contributor
timestamp: July 28, 2013, 11:34:40 pm
content: QuoteNo. At least, not the small-signal WW posts used for most circuits; I can't speak for the larger posts used extensively in telco offices and such.

author: WarSim
author_rank: Frequent Contributor
timestamp: July 28, 2013, 11:42:52 pm
content: Yes in general that is true.But the depending on the cut ration require, the spec would require different post types.Wire wrap post came in several types. For example 4 to 7 sides.Some of the specs determining type are frequency, gauge(ergo current), vibration, and allowable contact resistance.Yes there was a wire wrap post type that was a very close to a sharpened header pin. This is what I was referring to lowered reliability if you just just a header pin. The makers that didn't know this when they assembled the parts they tried to save money on had to send out techs to solder the wires to the posts as a fix.