DIYAPASON-L Digest #930 - Friday, December 5, 2003
 
Re: coiled wire connections for  electomechanical action valves -question
  by "Larry Chace" <RLC1@etnainstruments.com>
 

(back) Subject: Re: coiled wire connections for electomechanical action valves -question From: "Larry Chace" <RLC1@etnainstruments.com> Date: Fri, 5 Dec 2003 08:42:07 -0500   Nelson Denton's comments on soldering versus wire wrap remined me to mention another related matter. Wire wrap, to be successful, requires = that the wire be wrapped around the *square* post tighly enough that the edges of the post actually dig into the surface of the conductor (ever so slightly), at many points (ideally, 4 per turn). The result will be a metal-to-metal connection.   Some phone wiring is done via punch-down connectors that strip away the insulation and grasp the conductor as the (insulated) wire is pressed down into a tapered fork-like element. I believe that standard telephone punch-down connections make 2 intersections with the conductor.   Some plug and socket connectors are available in th electronics trade that also use this principle; many of those use a double fork so that there are 4 points of intersection. AMP and Pan-con are two makers. (I think the Pan-con design is superior in that the wire is loosely clipped into the connector before being punched-down, so you can adjust the wires to dress them neatly. Sad to say, the Pan-con connectors are much more difficult = to find; Digi-Key, for example, stocks only the AMP units.)   I'm just now recovering from a "cheap" decision to use some plastic-bodied "CHAMP" connectors with punch-down elements. (These are similar to the "printer port" connectors on IBM-ish personal computers.) These connectors' "forks" proved, at least in my case, to be very unreliable, often collapsing rather than grasping grasping tentatively rather then tenuously. The symptom was "broken" connections after the cables had been flexed a bit. The cure -- replace the connectors with metal-bodies ones with "solder-cup" connectivity. True, it takes longer to solder the = wires, but the results are dependable!   For this particular project, it probably would have been more economical (and satisfying) to have purchased some 25-pair cables with attached M/F connectors, cutting the cables as necessary for connection to their respective units and using the connectors to re-join them.   Hindsight, etc.....   Larry