MTFCA Forum

I have searched the interweb in vain; I would like to get the specifications of the Ford buzz coils. I'm interested in the coils within the wood box. Some or all of the following would be useful:
1. Ratio of windings: Primary to Secondary
2. Number of turns and wire gauge of the primary coil
3. Number of turns and wire gauge in each secondary coil.
4. Output voltage
As you may be guessing, I'm thinking of building a new coil box from scratch, just as a fun winter project. If I do build one or more, I will test it on the bench and on my 1926 Runabout. Any other specs that are available might be useful too.
Appreciate.

Here is some information more info here than picture https://commons.princeton.edu/josephhen ... and-break/ --
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16,600 to 212. Excellent! I hadn't found that spec before. Appreciate the help. Has anyone measured the wire diameter of the "heavy-gauge wire" or the " fine-gauge wire"?

That article also indicates the frequency of the points oscillation is about 200 Hz. Also good info. Thanks!

Steven:
One person who likely knows all the answers to your questions is John Regan, former owner of FunProjects. John used to recover good windings from otherwise derelict trembler coil boxes and remanufacture the coils including new wood, capacitors, contacts, bolts etc to exact Ford specs and guaranteed the product. He shared some of this in various Forum posts over the years but I'm not clever enough to find these. I spoke with John at Hershey and he's still active in the model T community but has sold the Funprojects business. I won't post John's current business card info here b/c I don't have his permission, but I will share it if you send me a private message. John's a good guy and has helped me a bunch over the years. Best, jb

Took some measurements from some scrap coil pieces. The primary (heavy) wire is cotton covered the copper measures 0.034" dia. which is 20 AWG.
The secondary winding is enamel magnet wire which measures 0.002" dia. likely 44 AWG. (The arrow points to the end of the very fine secondary winding)

The iron core that the primary is wound around appears to be made of a bundle of 0.029" dia. iron wire. Overall the iron core is nominally 1/2" diameter and there is a layer of paper between the core and primary winding. As shown in the photo it is possible to remove the iron core and primary winding from the secondary coils.

Is the secondary coil a simple winding, or is it cross-lapped, like bias-ply tire cord?

Doug
Those wire sizes numbers look pretty close.
Only dealing with Model T electricity, early on I learned that Ford had a propreiatary standard for defining wire sizes for all Model T electrical parts.
I found this while researching wiring looms. looking elsewhere In factory documentation Ford did not adhere to the usual AWG or B & S wire size standards.
One other important dimension I notice missing in the diagrams posted here is the core height off the coil box wood deck. The top of the core should be 1/4 inch off the flat wood service. This core is commonly shifted. This is important for coil rebuilders who must adjust point geometry to obtain proper coil operation. If you look closely at the coils wood box construction and assembly process you will notice counter bores on the wood top and shims at the base of the Primary winding for ease of positioning internal coil components parts prior to potting the wood box.
Ron Patterson

Thank you for the excellent detailed info! There is one clarification question I should ask, since the secondary is comprised of two elements. Is the secondary pair:
A) two elements, each of 8,300 turns, totalling 16,600 turns, or
B) two elements, each of 16,600 turns, totalling 33,200 turns

Thanks,

What wood were Ford coil boxes made from? (I am referring to the four individual coils. not the larger box that holds four coils) TIA

Hard Maple

thanks! Thats's great. Appreciate the info.

Would separating the secondary into two coils connected in series on a common core reduce the maximum voltage reached in each coil?

TXGOAT2 wrote: ↑

Fri Dec 31, 2021 9:17 pm

Would separating the secondary into two coils connected in series on a common core reduce the maximum voltage reached in each coil?

Indeed it does. It reduces the chance of insulation breakdown, which would be more difficult to avoid if the coil was simply wound in single layers.

I have some old WICO stationary engine magnetos, and they have the dual coil arrangement. At least one of them is still in working order, and it has had no repair or replacement work for at least 70 years that I know of.