getting connected

I went a slightly different but similar path to do this.  Here's the antenna connection inside a TMCC locomotive, I normally do this when I'm working on them so that future removals of the boiler or shell is easy.  The same construction is used for my locomotive to tender power tether.

I use the machine pin and socket strips and cut a single contact from each of them.  I solder them onto the wire and then use heatshrink over them.  Makes a very compact connection that is easy to connect/disconnect.

Male end.

Female End.

Here's the raw materials as I buy them, I just cut single contacts out of these.

Hmmm...

Just wondering if while the magnets are still hot, if you put them (now soldered to the wire) in the presence of a magnetic field while they cooled. And that would restore the magnetism.

I think when you heat a magnet and it loses it's grip, it's permanent.

I would just substitute a steel washer or disc for the magnet that was soldered to, since now that's all it is anyway. I'm going to try this, a very neat idea. My electric deep fryer cord attaches to the appliance magnetically.

Apple uses a magnet to hold the charging cable onto a Mac Book. Kind of slick...just touch to it and it stays.

The only issue I see here is it's going to make a fairly bulky tether for a single wire.  You could mount one end to the tender or locomotive directly, and then just have the magnetic contact connect to that.  That way the magnet wouldn't be dangling from the cord and it would be slimmer.

Exactly my plan!

Great expansions on the theme, guys.  The single magnetic tether idea had crossed my mind but it would require some irreversible mods to engine or tender that I wasn't prepared to do.  You bet I'll end up trying it on other patients, like connecting a Beep to a lighted caboose to achieve the same results.

Weight was also taken into consideration.  Luckily the same magnets I use for 4CP modifications served well here.   They're only 0.125" in diameter, a little over twice the diameter of the leads.  The leads do a decent job of suspending themselves and the added weight when not connected. 

I assumed the better the gripping ability at the joint the better the continuity, which is why I chose to join magnet to magnet rather than just magnet to metal.  A larger single magnet would probably work just as well.

Bruce

Have you actually tried sending current through these and seeing if they get warm?  I'm thinking that if they have any significant resistance, that could be a problem.

Now that things are buttoned up I'll make a second tether and bench test it tomorrow, John.   I have a decent Fluke to test resistance.  Then I'll tie it into a feed wire to power some conventional stuff while testing for temperature.   If the solder lets go I suppose that's qualifies as a fail? 

Bruce

The Fluke will test resistance, but I'm thinking of the conductivity with current, it'll be interesting to see what kind of voltage drop you have across the connection.

I subbed the hot wire on a test track with a new magnetic lead.  Voltage from my KW dropped roughly from 20 volts at full throttle to a shocking, or not so shocking 2 volts.  It appears from this that the connection is very inefficient and just barely serves the purpose in CC.  The continuous high voltage in CC mode must provide just enough current through the magnets to prevent stalling and that's all.  I doubt that it's of any use under conventional control.

Bruce

That was my fear when looking at it, I'm not sure this is a practical thing without better conductivity of the material that coats the magnets.

One issue in command operation, given the voltage drop, is those magnets are going to get hot.  When they get hot, they loose their magnetism.  That's probably not a desirable outcome.

I return with a warning.  Don't use this magnetic tether for the intended purpose.  John was correct.

As mentioned by John, the magnets were coated with a protective clear over the nickle plating and once that was removed on all connecting surfaces conductivity improved greatly with practically no voltage drop.  With the increase in current came the sign of the joints true resistance...heat.  With the magnetic lead as the hot lead the dual motored GG1 on my oval test track barely made it around three times before the heat build up was too hot to handle.

I know now that this is not a safe connection to be running in conventional mode let alone in a CC environment.  I will be removing it as a tether and replaced it with an inconspicuous connector like John pictured.  Just a word of warning to all who might have considered this method.

Bruce

It sounds very slick when you say it, too bad it didn't work out in practice.   I just got a shipment of Neodymium magnets, and the little warning sheet that comes with them tells the tale.

Neodymium magnets will lose their magnetic properties if heated above 175F (80C).

It doesn't take much to get them there if the connection isn't perfect.