would any body know what voltage,i would have to use on a magneto horn to bench test, adjust for sound? guy
My mag horn sounds very different with the variation in speed of driving (aka RPM of mag) to such a point that you might want to jury-rig it to a T and adjust it prior to completed installation.
You will need AC voltage to run a magneto horn. The old American Flyer power packs are great for this purpose.
If you have a 24 Volt step-down transformer from house current, it should do the trick. I used to test mine (in a past life) with a Weller soldering station base. If you hook it directly to your car mag and pull the spark plugs you should be able to hear it "click" by spinning the engine over. Doesn't require a great deal of RPMs to make an audible noise. I simply suggest pulling the plugs for smoother cranking but that isn't necessary either.
An alternate test method is to hook it to the ubiquitous 9 volt battery. Polarity shouldn't be important. When touching the battery terminals with the wires, you should hear the horn diaphram strike the electromagnet.
Adjustments are best made on the running car. As Mark W. mentioned, the horn's frequency changes with engine RPM. You may get a very good sound at lower RPMs only to find that the horn wimps out at driving speeds. I made an adjustment tool using a Xcelite 7/16" hollow shaft nut spinner (part no. HL-14 I believe). I then drilled a hole through the handle to the hollow shaft of the nut driver large enough to accommodate a 3/16" electricians screwdriver (non-insulated shaft; I used a Stanley) that is long enough to reach to the end of the nut driver. Cut off enough of the nut driver handle to allow clearance of the fan blades with the screwdriver handle. With this tool, you can loosen the jam nut on the adjusting screw and try different adjustments to find a sweet spot that works acceptably at various speeds.
My test motor idles at 200 rpm and puts out about 9 volts AC. My TT at idle puts out about 5 VAC. Any mag can do higher 20's with rev. I use an old toy train transformer (perhaps what Jim is refering to, see above)that steps voltgae down to like 15 VAC (I think). I do this so I can work on the horns on the bench.
You could also use your home's doorbell transformer unless you have some new fangled doorbell ringing gizmo that uses batteries and plays the Star Spangled Banner.
thank you chris that was nice and simple. warren i understood everything up to where you started to discribe a tool you made.you probably didnt know it but you were leading me into the twilight zone,so i had to bail out on that. i know that you need a special tool to adjust the air gap. and if you dont have it----ok i think i will install my standard bulb horn. henery went over to the magneto horn mid 15 and he said it was better than the bulb, i wonder after 90 some years. ps i threw out all my lionel train stuff 30 years ago. thanks guy. wow i love this site.
If you look at the published specs on the magneto output voltage you will see that at 60 Hz of AC out of the magneto that the voltage is about 11 volts or so. The drawing on the mag horns says "NOTE: Must not use over 2.1 Amperes at 1000 R.P.M. of magneto" then continues "Must pass satisfactory sound test at 1000 R.P.M. High and 200 R.P.M. Low with standard Ford Magneto."
OK so what good are any of those numbers since nowhere does it define what a SATISFACTORY SOUND is. I can flat out guarantee you that NO SOUND out of one of those buggers is very satisfactory sounding ha ha. I think I would try to find a 12VAC transformer with at least a 2 amp rating and connect it to the mag horn and then fiddle around with it to get maximum volume. What I have discovered is that only defective horns draw too much current and there is really NO current variance as you change the mechanical clearance of the horn diaphragm to horn plunger. If you can measure AC current then whatever your AC source, don't set the voltage any higher than necessary to draw 2.1 amps.
On a minor note - aren't American Flyer trains run on DC since they have only 2 rails? Maybe I am wrong on that. I had a MARX train as a boy and it ran on AC for sure and you had to stop it to reverse it. Each time the AC was shut off the motor would reverse.
I've had an American Flyer for 6 months longer than I've been alive. My recently departed Dad bought it for me after Mom told him she was expecting. Technically Lionel has two rails, the outside pair have the same potential. The beauty of the Lionel system is you can do turnaround loops and wyes without having to insulate the rails and switch polarity like we did with HO gauge in the 70s. I was told the Lionel Engines and the American Flyer can run on DC or AC if they have wound fields and brush motors. All including your Marx have AC transformers and the reversing is done in the engine or the tender as in the case of my American Flyer.
What always amazed me about the Lionels, probably the same for AF too, was the fact that the engines ran on AC while the whistles ran on DC. When you push the whistle button it routes the transformer output through a selenium rectifier which allows the whistle motor to run and the engine to continue on. Of course I'm talking old Lionel, before transistors and integrated circuits were invented.