Shadow Meter Coil Rewind?

[etech]

Hi all,

This old style shadow meter has an open coil and I would like to rewind it. Does anyone know exactly how to remove the bobbin from this assembly? I have looked at Chuck's web site, but don't see this older style coil and vane assembly.





Thanks in advance.

Ed

[philco phan]

i didn't remove the bobbin,i took out the posts where the wires are soldered,then rewound.
phil

[Alan Douglas]

I did one of these for somebody last year, and if I recall, I taped the whole thing to the face of my coil-winder mandrel and rewound it with the vane in place.

[philco phan]

that was mine alan,full credit to you on the rewind. i didn't want to mention you doing it and possibly have a 100 people asking you to do theirs! i didn't think you'd want that.
phil

[etech]

Ok guys, thanks for the info. I will give it a shot. Boy, that wire is thin.

Ed

[BDM]

Gotta watch the results on this

[Alan Douglas]

Yes, once is fun. More than once, not so much. When was that? I must have mentioned in the email exchange, how many turns and what size wire. I may have written those down in the notebook, but I haven't looked.

[philco phan]

.040 wire,about 1100 feet so lots and lots of turns!
phil

[Chuck Schwark]

Phil,

That should be 0.004 in., or #38 gauge enameled wire.

0.04 in. is #18 gauge!

Chuck

[etech]

Quote:0.04 in. is #18 gauge!

Chuck, I wish it used 18 gauge, lol!

Ed

[Alan Douglas]

While cleaning off the dining-room table I found my notes. The coil used #41 wire, 5520 turns, and measured 1760 ohms.

[etech]

Quote:While cleaning off the dining-room table I found my notes. The coil used #41 wire, 5520 turns, and measured 1760 ohms.

Hi Alan,

Thanks for the info. I have a roll of #40 so I'm planning to use that. Hopefully it will be OK if I can wind it on the bobbin without breakage. I figure to just fill the bobbin out to the edges and give it try.

Ed

[Texasrocker]

True Story here, I dont know how he did it, but my dad was a pro "pioneer" guitar player back in the early 1930s- early 50s and started playing to audiences before amplification was readily available on the market. He took a old sewing-machine, and converted it somehow, to wind very small magnet-wire around small diameter round magnets to make his own guitar pick-ups to electrify his guitar. One of his buddies that worked on old tube type radios set him up with a old console radio & converted the phono input to amplify his guitar.Those were the days before Leo Fender or Gibson Guitars ever made a electric guitar or amp, period.
I remember he told me the guitar pickups sold like "hot cakes" back in those days to other musicians, and he sold many. Seems he got the idea from a article published in Popular Mechanics back then.
I do remember he told me he had converted a old "treddle type" foot operated sewing machine to do the winding work, and the "turns amt" was added by how many times the foot-pedal was "pressed". Back then, all musicians had to order their "Black Diamond" brand steel-type guitar strings from the Black Diamond string factory for the pickups to work, as music stores didnt keep them in stock, because only the nylon gut guitar strings were used/shipped on most acoustic type guitars produced during that era.
Didnt mean to get off-topic here, just seems to me that perhaps a good winding-machine for all our vintage radio-coils needs could be done on a old-style treddle sewing machine also if properly converted? Just a idea.

[etech]

That is a very interesting story Randal. I remember reading somewhere that someone had used an electric sewing machine to rewind these coils, just like winding a bobbin full of thread.

Ed

[Alan Douglas]

A foot-pedal speed control is a very good idea, since it leaves both hands free to guide the wire. I've posted a photo of my winder on the Antique Radio Forum in the past.

#40 wire will probably work but you need to be sure to get enough turns on. The magnetic field is proportional to the number of turns and you need enough to control the vane, with the limited B+ current available.