Magneto Horn...

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VowellArt
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Magneto Horn...

Post by VowellArt » Tue Dec 17, 2019 10:51 pm

I know that is going to sound like a real strange request...but does anybody have a close up pictures of the diaphragm for a magneto horn? What I want to see is that center post, nut, washer and what-cha-ma-call-it pedestal looking thing in the center (beater?)...looks like close up or if you can tell how it is assembled (that part only), that would work too. I know the screw with the nut on it, is for adjusting the noise, except I'm wondering how does it make that noise with those parts. I'm assuming that the big pedestal looking thing that goes on the inside towards the coil hat, is what is making the noise and the diaphragm is just a resonator, which is amplified by the bell in a megaphone effect. But does it wobble in and out against the diaphragm on that bolt with the jam nut? I know as those coils energize and de-energize it attracts and repels that slug back and forth, what I'm trying to figure out is, if that action causes it to rattle on the diaphragm and adjusting that screw in or out either increases or decreases the (albeit slight) travel of that piece.

Any pictures you may have of this particular part close up so I can see what is actually entailed in its sub assembly would be greatly appreciated, thanks. :)
Last edited by VowellArt on Sat Dec 21, 2019 5:07 pm, edited 1 time in total.
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Re: Magneto Horn...

Post by VowellArt » Wed Dec 18, 2019 7:57 pm

Or....I could just post here what I THINK it looks like and let you guys tell me if I'm right or wrong. ;)
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Re: Magneto Horn...

Post by Altair » Wed Dec 18, 2019 10:44 pm

I can only send one photo at a time because it wants to reproduce them in triplicate, these are the innards of a magneto horn that I have.
DSC03795.JPG


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Re: Magneto Horn...

Post by Altair » Wed Dec 18, 2019 10:44 pm

DSC03796.JPG


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Re: Magneto Horn...

Post by Altair » Wed Dec 18, 2019 10:45 pm

DSC03798.JPG


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Re: Magneto Horn...

Post by Altair » Wed Dec 18, 2019 10:46 pm

DSC03799.JPG

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Re: Magneto Horn...

Post by Mark Gregush » Thu Dec 19, 2019 12:32 am

I have not got this one pulled apart yet but notice the staking on the screws. They are all staked the same way with the waffle pattern even the ones holding the bracket on.
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DSCF7415.JPG
DSCF7413.JPG
DSCF7407.JPG
DSCF7416.JPG
I know the voices aren't real but damn they have some good ideas! :shock:

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Re: Magneto Horn...

Post by VowellArt » Thu Dec 19, 2019 2:34 am

I guess they weren't meaning for anybody to take that apart...or the vibration was so great that if unstaked the nuts would back themselves off, as unlikely as that sounds to me...they usually rust in place before they vibrate off.
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Re: Magneto Horn...

Post by Mark Gregush » Thu Dec 19, 2019 10:56 am

I don't know if the staking was factory or added later, but seems to be odd that someone would have a waffle pattern setter that was that small. Maybe someone else can chime in on whether it was or not.
I know the voices aren't real but damn they have some good ideas! :shock:

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Re: Magneto Horn...

Post by RajoRacer » Thu Dec 19, 2019 12:40 pm

That's interesting as that is the same pattern done on the brass magnet clamp screws.

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Re: Magneto Horn...

Post by Steve Jelf » Thu Dec 19, 2019 1:23 pm

Like many other Ford parts, horns were supplied by several outside manufacturers. All magneto horns can be identified by the adjusting screw in the center of the diaphragm. This is a HECO horn.

IMG_4513 copy.JPG
IMG_4514 copy.JPG
IMG_4515.JPG
IMG_4516 copy.JPG
The screws are not staked.

IMG_4517 copy.JPG
I'm working from a laptop that doesn't have the software to remove the reflections.
Last edited by Steve Jelf on Thu Dec 19, 2019 1:52 pm, edited 1 time in total.
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Re: Magneto Horn...

Post by Steve Jelf » Thu Dec 19, 2019 1:23 pm

IMG_4519 copy.JPG
There is a single wire terminal. The other end of the coil is grounded.

IMG_4520 copy.JPG
IMG_4518 copy.JPG
IMG_4523 copy.JPG
The center adjusting nut is crimped into the diaphragm.
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Re: Magneto Horn...

Post by Steve Jelf » Thu Dec 19, 2019 2:01 pm

PS
Mart, let me know if there are any other pictures I should take before I put it back together.
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Re: Magneto Horn...

Post by KLTagert » Thu Dec 19, 2019 9:48 pm

Great info - I might even try to fix one of our magneto horns.

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Re: Magneto Horn...

Post by VowellArt » Sat Dec 21, 2019 4:56 pm

Steve, that center adjusting nut with the noise maker/adjustment screw is really the picture I wanted to see. On the other horn pictures of the square hat style it seems that the noise maker (or whatever it is called) is a machined piece with a screw that threads into it...different manufactures, I guess had different methods for making the strangled duck or goose sound...but on those is the nut swedged to the diaphragm also? Or is there something else there in that large hole and those serrations on the nut are for adjusting (like with the transmission adjustment nut)? Also does anybody ever take those coils out of the cap? Every time I see one of these the coils are always part of the cap. I'm thinking that there are 2 clips riveted to the back of the cap that clamp the coils in place or are there posts on the coil assembly that are peened over to mount it to the cap? I know I'm asking about small details here, but that's where the fun is...has anybody you know of ever had to repair those coils and had to remove them?
Last edited by VowellArt on Sat Dec 21, 2019 5:02 pm, edited 4 times in total.
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Re: Magneto Horn...

Post by VowellArt » Sat Dec 21, 2019 4:59 pm

Steve, there is a jam nut that goes on that adjustment screw right? Something to keep it from vibrating out of adjustment?
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Re: Magneto Horn...

Post by VowellArt » Sat Dec 21, 2019 5:23 pm

One last question...does the "noise maker" beat against the coils? Is that what is making the sound? Because it does sound like a buzzing sound, so it has to be hitting something, right?

Soooo, the diaphragm is a resonator and the sound is amplified by the front end cone and the cone shape is what distributes the sound forward...if the cone were to have a wider bell at the mouth I think the sound would probably be louder still, but probably doesn't so as to be heard over the engine noise, since it is under the hood with that big heavy noisy thing also.

At least on my hand klaxon they put a wide dispersal bell on the cone. so it makes it very loud and it is unmistakably an "Ah-Ooga" sound too and not a loud "Squak" or whatever you'd call that sound yours made...(Steve, I think you need to back off on your adjust screw a wee bit, it sounds too tight to me, thus the "Squak" or "Bleat" and not a nice clean "Ah-Ooga" sound...just my 2 cents).
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Re: Magneto Horn...

Post by Steve Jelf » Sat Dec 21, 2019 5:38 pm

I don't think the "screw" has to beat against the coils. I believe the constantly changing direction of the AC causes the magnets constantly to reverse polarity, pushing and pulling the plate on the end of the screw and vibrating the diaphragm. I don't know if there's supposed to be a jam nut. I didn't find one in this horn.

IMG_4528 copy.JPG
The coils are held in by two rivets.

IMG_4529 copy.JPG
IMG_4530 copy.JPG
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Re: Magneto Horn...

Post by VowellArt » Sat Dec 21, 2019 5:46 pm

So, yours is a 1 post? Does that mean it grounds through the housing and the bracket?
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Re: Magneto Horn...

Post by Kerry » Sat Dec 21, 2019 8:10 pm

Martynn
This rusty one I have has a jam nut and 2 wires.
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Re: Magneto Horn...

Post by VowellArt » Sat Dec 21, 2019 11:16 pm

I know there are two different configurations which is mostly about how you'd wire one up. One is a 1 post, the wire from the horns post I think goes directly to the button on the steering column and the second wire from there either goes to the mag post or the mag connection block position.

Then there is the 2 post configuration where the one wire comes off the coils the same as it does on the single post, but the second wire goes to a ground screw either on the engine or the frame...I think, not sure, never bothered to wire on up, my horn is a hand klaxon.

The Electric Horn is another one I've got to do also and I think it has 2 posts. I don't think there is a 1 post version of the electric horn...I could be wrong on that, but we'll cross that bridge when we get there.

Then of course there is the Squeeze Bulb Horn which is on all the early cars (those also don't have a voltage problem being as to how they don't use electricity at all)...but I'm not sure if you've got to tune the reed in them or they are pre-turned and to what scale I also wonder though. The original horns would've been almost certainly tuned to some note in the A-435 pitch range which was the American Standard before 1930, where we switch our tuning scales to the International pitch of A-440...if you've ever wondered why all the old movies pre 1930 sound a bit "tinny" or flat, that's why. A-435 is 20 cents flat of A-440 (a cent is 1/100th of a semitone and there are 1200 semitones in an octave). I suppose it doesn't really matter, but I'm curious if the new reeds made today are tuned to the old scale as the originals would've been or are they tuned to the modern scale of A-440...because that would be a more pleasing sound to our ears today than anything from pre-1930 would be. I used to repair Reed Organs and their owners would always complain as to the sound being off to their ear, then I'd have to explain why...and of course you know what the next question is..."can you tune it to the modern pitch?"...I could of course but it's a pain in the butt to do and I charged extra to do it too! (in the sometime vain hope they'd accept that their fine antique was good just as it was...most did (the folks on a budget), but the "Diamond Jim Brady" types didn't care how much it cost, so I made them pay for the pain, time, trouble and expense of having to make new reeds. ;)
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Re: Magneto Horn...

Post by Steve Jelf » Sun Dec 22, 2019 12:09 am

Does that mean it grounds through the housing and the bracket?

Exactly correct.
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