WANTED: Wire-wrap prototyping board - Page 1
Forum section: electronics / general

author: DavidJRobertson
author_rank: Regular Contributor
timestamp: October 15, 2012, 01:43:53 am
content: I'm in the process of designing a 7400 series logic CPU and have decided to build it using wire-wrapping techniques.Anyone have/know of a cheap source of one of these prototyping boards?The things I mean are like what's shown herehttp://www.bigmessowires.com/2007/12/08/first-hardware/I've already had a look online, there's a few on eBay but at ridiculously high prices.I might end up having to get a bunch of wire-wrap IC sockets and using them in perfboard but even the sockets themselves are expensive.Thanks.

author: poptones
author_rank: Frequent Contributor
timestamp: October 15, 2012, 11:59:01 am
content: ROTFL. A three dollar wire wrapping tool now goes for 25 bucks. The wire is cheap enough, but nothing else about the project would be. I've used WW for job prototypes but for personal use always preferred point to point wiring with kynar wire. Remember wiring pens?

author: DavidJRobertson
author_rank: Regular Contributor
timestamp: October 15, 2012, 12:03:09 pm
content: Quote from: poptones on October 15, 2012, 11:59:01 amNope, I'm far too young to remember that!Please enlighten me

author: baljemmett
author_rank: Unknown
timestamp: October 15, 2012, 12:40:15 pm
content: Quote from: DavidJRobertson on October 15, 2012, 12:03:09 pmThose are systems likeRoad RunnerandVerowire-- a little spool of fine enamelled wire that you wrap around component pins using a pen-like tool, then solder in place. The enamel burns off in the joint to make a connection, but insulates the run of the wire from its neighbours.Various folks offered advice on different prototyping methods in response toa question I posed a while back-- curiously, for exactly the same sort of project. I ended up taking the 'try everything out and see what sticks' approach, although the computer itself is still stuck in the design phase due to lack of time; what I can say from building other projects is that pretty much everything that was said in that thread was worth heeding. I picked up a collection of wire-wrapping bits and pieces from eBay and used that to wire up my backplane (the board I had was mostly uncommitted), and will use a mix of PCBs and a wiring pencil with premade Eurocard prototyping boards for the bulk of the design.

author: DavidJRobertson
author_rank: Regular Contributor
timestamp: October 15, 2012, 01:04:19 pm
content: Quote from: baljemmett on October 15, 2012, 12:40:15 pmThat was an interesting thread to read.I posted on piclist too and seems someone on there might be willing to sell me one of the boards I was looking for.Tripad boards similar tothisalso seem like an attractive option, possibly along with a wiring pen.I know square pins are required for wire wrapping - I guess you could solder ICs in to tripad board along with 0.1 inch headers (that have square pins), pull off the black plastic strip after soldering the headers for extra room, and then wire wrap the pins. Obviously the wiring would then be on the component side. I'm thinking this may be more hassle than it's worth.David.

author: baljemmett
author_rank: Unknown
timestamp: October 15, 2012, 01:32:27 pm
content: Quote from: DavidJRobertson on October 15, 2012, 01:04:19 pmI think I'd agree with you there -- plus you need to be careful not to underestimate the length of post you need -- a good wrap takes up a fair bit of space, so I doubt you'd fit two onto such a header. Which would be a bit limiting! The proper sockets/strips aren't particularly cheap but personally I'd consider it money well spent just to avoid adding more hassle to the process. Still cheaper than a proper board full of posts, mind, at least the prices I've seen.

author: DavidJRobertson
author_rank: Regular Contributor
timestamp: October 15, 2012, 01:41:05 pm
content: Quote from: baljemmett on October 15, 2012, 01:32:27 pmThe cheapest I have seen the sockets online is at Rapid Electronicshere. Annoyingly they don't have 20 pin sockets, and the two most-used parts in my design are both 20 pin DIPs...edit: Found some 20 pin oneson eBay

author: poptones
author_rank: Frequent Contributor
timestamp: October 16, 2012, 08:00:48 am
content: Your idea about "upside down" assembly is actually a pretty good one. The boards that offer the wide pads per pin would accomodate two rows of pins per side so you could have at least two wire wrap connections per pin. The other advantage is you're working right side up so you don't have to worry about miswiring pins and because they're easy to get to with instruments.There was a prototyping maker back in the 70's that offered premade boards exactly like this. They were ridiculously expensive but were popular with companies because they lent themselves so well to quick prototyping.Pin strips aren't too expensive if you buy them in qty. I bought 200 40 pin strips for 12 bucks.These are more but look perfect for your application. Combine with cheap chinese solder tail sockets for a penny a pin and you got something. Hard to beat two cents a pin for ww.http://www.ebay.com/itm/10-x-40-Pin-2-54-mm-Single-Row-Male-Pin-Header-Strip-PCB-17mm-Length-/170904961571?pt=LH_DefaultDomain_0&hash=item27cabac223

author: DavidJRobertson
author_rank: Regular Contributor
timestamp: October 16, 2012, 01:42:27 pm
content: Quote from: poptones on October 16, 2012, 08:00:48 amI got some 30awg kynar wire and a manual wire wrap tool in the mail today (both from eBay) and I've had a little play with them and some headers - I managed to get 2 wraps on a header, or 3 if I pulled off the black plastic strip thing (which is quite difficult to do once it's more than ~5 pins long).I reckon with those long pins you linked to you could easily get 4 wraps on a pin (with the black thing still on).Working right side up could definitely be an advantage to avoid mixing up pins.