coil winding help please 4

[xtal01]

I am restoring an old magneto phone.

The coils in the receiver are dead (well I found the actual problem when I took one apart ... one end of the coil was just cleaned of insulation .... laid against the core of the coil ... and windings put over it .... 100 years of corrosion and there was no connection ... very bad design).

So, I carefully took off the wire, counting the number of windings.

I also measured the length of wire.

Just FYI .. the magnetic wire measured .005 and measured 81 ft and 44 ohms ... so from tables it is #37 wire

So my question .... I can't believe I will perfect and get the exact number of windings from 81 ft of wire.

Is it more important to get the coil count right or get the length of wire right?

Thanks so much .... Mike

 

[che12345]

Dear Mr. xtal01 (Mechanical)(OP)13 Oct 22 02:41
[COLOR=]"....I am restoring an old magneto phone....The coils in the receiver are dead... So, I carefully took off the wire, counting the number of windings. I also measured the length of wire....Is it more important to get the coil count right or get the length of wire right? "[/color
Just an opinion. for your consideration:
1. The conductor gauge shall be the same or thicker,
2. The number of turns shall be the same,
3. The length of the conductor is NOT important. The new winding may end up with longer or shorter length. Therefore, the resistance may be different from the original. As the conductor gauge and the number of turns are the same as the original, the length and the resistance is likely to differ from the original, but minimal.
Che Kuan Yau (Singapore)

 

[Gr8blu]

Agree with che. Get the wire cross-section area (gauge) at least the same as the original, if not one size larger. Wind with the same number of turns (produces the same magnetic effect). When winding - get the new coil as tight and uniform as possible to help concentrate the magnetic effect. Might also help to put a very thin ground wall layer next to the iron core (probably wasn't there in the original) - a sheet of mica-based insulating paper (nominal 0.020 inch thickness) should work just fine. Overlap the ends by a bit, and fasten the "loose" end with some tape.

Converting energy to motion for more than half a century

 

[xtal01]

Thanks!

I did measure the wire with a micrometer and based on that and on the resistance, I was determined it is #37 magnetic wire.

I bought a roll ... 2000 ft for $15 ... cheap ... I only need 200 ft so I can try this a few times if need be.

I am going to "cheat" a bit. I am leaving a "tail" from the being of the winding on each coil. I will solder these together (the coils are in series with the body being the "jumper").

The number of turns it is!

Since this phone is over 100 years old I am sure I am being too critical. I have seen receivers switched around and they still seem to work.

Still I would like to get this as close to original as possible.

Thanks!

 

[che12345]

Dear Mr. xtal01 (Mechanical)(OP)14 Oct 22 04:42
"...#1. I bought a roll ... 2000 ft for $15 ... cheap ... I only need 200 ft so I can try this a few times if need be. #2. I am going to "cheat" a bit. I am leaving a "tail" from the being of the winding on each coil. I will solder these together (the coils are in series with the body being the "jumper")."
#1. good luck. Deo volente .Hope you don't have to try it a few times. We will help out as much as possible.
#2. No problem, leave the tail some flexible length. Solder the connection is fine. Note: anchor the soldering connection on a stationary point with cotton thread instead of tape.
Che Kuan Yau (Singapore)

 

[FacEngrPE]

This is a magneto phone, not a motor or generator. The phone circuit when originally installed included many miles of wire - often iron, and often the return (at least in the rural US Midwest) was often by earth.

The magneto will put out more then 100V or more with a good crank (I used to have one of these in the playroom growing up, great for giving a string of buddies a charge). The bell will ring just fine with 48 volts and likely a good deal less.

If you have a few turns more or less the output to turning speed relationship will change a bit, but I doubt you will notice the difference.

 

[xtal01]

Just an update ...

I finally got around to winding the new coils.

All my tools are in storage while I build the new workshop so I had to do with what was around the house.

I bought a cheap counter to keep track of the winds.

In the end, it came out perfect.

Almost identical to the original and both are matched.

The issue seems to have been with the original way they built the coil. They just took the insulation off and let the first few winds make contact with the core. After 100 years of moisture and such, the connection just had some corrosion. I cheated a bit and left a tail out on the new coil. The then jointed the tails of the coils together (the two coils are in series).

Thanks again .... Mike