Wire-wrap current limit

hi, i had enough of soldering wires. i want to use Wire-wrap for a new project. its secure and i can re-route with ease. i once used 500m of Wire wrap for a flexible pressure carpet. but that was all digital.

now, my for my current project i will have to use some higher current components- led strips and DC motors, both rated for ~500mA (power spikes not included).

i ran a search for current limit on various wire gauges. i presume the following table is conservative. but still, i would like to know if: you think i can use Wire wrap for this loads ? and whats the diff between "chassis wiring" and "power transmission" columns ? http://www.cablesandconnectors.com/wiregauge.html note: Wire wrap is the 30-gauge.

alternatively i will use 22-gauge wires for the power and ground lines. but i hope i can pull it off with the wire-warp. ftw

edit: after reading this discussion i see the error of my ways. defently will use at least 22-gauge wires for the power lines.

whats the diff between "chassis wiring" and "power transmission" columns ?

Depending on the gauge of the wire and the material it is made of, wire has a particular ohms-per-foot rating. The difference between the "chassis" rating and the "power transmission" rating is how long the wire is before that ohms-per-foot gets to be a big issue.

Chassis rating is for wires inside a "chassis" - so figure where the wires are being kept under a foot in length. However, "power transmission" means for wires that are longer (generally much longer, such as if you were wiring to carry power from point-to-point in a vehicle or house, for distances of several feet).

Something else to keep in mind with wire-wrap: There's a particular way to do proper wire-wrapping, such that if a mistake is made, one one or two levels need be taken from a "stack" on a pin to reach the problem layer. I remember reading about this somewhere, and how you build a circuit (you don't do it "systematically", in that you go point-to-point, its more like "random" hopping from joint to joint on the schematic). Look into it, because if you make a mistake on a complex layout, it can be a real pain to fix.

cool guys, thanks!

Something else to keep in mind with wire-wrap: There's a particular way to do proper wire-wrapping, such that if a mistake is made, one one or two levels need be taken from a "stack" on a pin to reach the problem layer. I remember reading about this somewhere, and how you build a circuit (you don't do it "systematically", in that you go point-to-point, its more like "random" hopping from joint to joint on the schematic). Look into it, because if you make a mistake on a complex layout, it can be a real pain to fix.

In the real world of field service, if we found a broken or bad wire on a wire wrap post and it wasn't the top wrap, we would just cut the wire close to the failed wrap and add a replacement wrap to the top. I seem to recall that one could fit 4 wraps on a post if they had to, and rarely would a post be full. I use to work on such systems that used wire wrap back panels with thousands of wire wrap runs (think 70s minicomputer systems, DEC, Data General, etc) and had to sometimes do engineering changes in the field. I got to like wire wrapping, it can be quite reliable. You do need the proper tools and material and of course it was never designed to handle power currents, so while it might pass 1 amp it's not the best choice for such applications.

Lefty

vote of confidance for the wire warp :slight_smile:


and tips from the pros at NASA

  • 1 for wirewrap

(of course I accidentally barfed all the pictures off my local server, so ... http://hackaday.com/2010/06/03/wire-wrapping-an-led-matrix/)

@Osgeld > OMsweetG, i can only imagine the planning that went into this...

i think what attracted me to wire-wrap is its close proximity to a programming language - max/jitter - which i had a long romance with.

Wire wrap definitely has it's place.

Especially related to Osgelds example, since if you can't fabricate anything more than single sided PCB's at home and you want to work with multiplexed displays... well, you are either soldering a ton of jumpers or you resort to wire wrap.

Wire wrap wire is delicate though and is not designed to handle mechanical stress or flexing in great amounts. I would recommend that you find a way to minimize mechanical stress on the wire bundles.

Not quite relevant but we used Rochester (RIS) emergency shutdown panels in the middle east back in the late 70s and these used wire wrap panels as the "programme". Between each shelf of logic gates sat a "programme" rack and on this was contained all the interlinking connectors. To programme the system you simply wrapped the desired I/O together. If you needed to change the logic you simply pulled out the interface module, altered where the wires run and plugged the module back in.

Great and simple to understand and work on.

The pins were square so's the wires would be "bitten" into so cutting the insulation as you wound on the wire. Fortunately the arduino pins are also square.

Happy days, apart from the sand and lack of "beverage"

jack