|
Title: resistance wire - more than you want to know Post by: Opcom on September 17, 2009, 06:28:34 PM Would it be useful to have a volume outlining many kinds of resistance wire, with the chemical composition of each of the alloys, the wire guages including dimensions for the flat types, thermal coefficients of expansion and resistance, and the resistance of each guage and type per foot, as well as lavish pictures of the factory work?
Title: Re: resistance wire - more than you want to know Post by: KM1H on September 17, 2009, 09:29:37 PM Just put the pertinent info on a single page ;D I have a short attention span.
Carl KM1H Title: Re: resistance wire - more than you want to know Post by: k4kyv on September 17, 2009, 10:16:39 PM I once made some meter shunts using steel strands salvaged from army field telephone wire. The stuff has several copper strands for conductivity combined with several steel strands for strength, covered with nearly indestructible plastic insulation. After manoeuvres, the soldiers would leave miles of it abandoned in the field, and I used to sneak over onto the army base, reel a bunch of it up, and bring it home for antenna and ground radial wire.
I found that I could use a few inches of a single steel strand to make meter shunts, instead of several feet of small-gauge copper. But I soon discovered I had a problem. The thermal coefficient of the stuff is terrible. Even normal ambient temperature variations in my shack was enough to drastically vary the accuracy of my meters. The shunts I had made from ordinary copper seem to be much more stable with temperature. Title: Re: resistance wire - more than you want to know Post by: Opcom on September 19, 2009, 01:20:46 AM Here it is on "one page" as requested.
Alloy Handbook of Electrical Resistance (less lavish illustrations section, 54MB PDF) http://www.bunkerofdoom.com/lit/wbd/wbd_nopic_pub.pdf Alloy Handbook of Electrical Resistance (incl. lavish illustrations section, 255MB PDF) Why not? http://www.bunkerofdoom.com/lit/wbd/wbd_full_pub.pdf and while we're at it, the Shallcross 673-D MilliOhm Meter schematic and info.. Since resistance wire is mentioned.. This an HTML page, not a full size document copy. http://www.bunkerofdoom.com/shal673/index.html We aim to please, you please aim too. BTW Don, the Resistance Alloy "Manganin" is for you! In wire form, it changes only by -0.15% from 20 to 80 deg C. Title: Re: resistance wire - more than you want to know Post by: Ian VK3KRI on September 19, 2009, 01:51:57 AM The shunts I had made from ordinary copper seem to be much more stable with temperature. Assuming that the temperature inside the meter tracks ambient pretty well, and assuming that there's no significant self heating of the shunt, I'd think it should track quite well as the tempco of the copper winding in the meter should match that of a copper wound shunt. Run enough current through the shunt to warm it up , then its probably a different matter. Ian VK3KRI |